The Landscape of Influential Factors on Fecal Calprotectin in Convalescing Preterm Infants (Corrected Age of 10-18 Months)

The Landscape of Influential Factors on Fecal Calprotectin in Convalescing Preterm Infants (Corrected Age of 10-18 Months) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Landscape of Influential Factors on Fecal Calprotectin in Convalescing Preterm Infants (Corrected Age of 10-18 Months) Yaqi Liu, Kan Ye This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8459794/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose To investigate the factors affecting fecal calprotectin in preterm infants at the corrected age of 10–18 months. Methods This research employs a cross-sectional design. Infants with a gestational age of less than 37 weeks were recruited at a corrected age of 10 to 18 months (born between April 2023 and April 2024) from the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University between June 2024 to August 2024. The fecal calprotectin was measured and was classified into three grades: 60µg/g. Relevant information was collected. Results Fecal calprotectin levels in preterm infants who received formula supplementation before 6 months of corrected age were lower than those in infants who received it after 6 months. In convalescent preterm infants with constipation, fecal calprotectin levels exhibit a mild elevation, typically below 60 µg/g. Probiotics demonstrate a more pronounced effect on improving fecal calprotectin grades rather than content. Conclusions Compared with non-exclusively convalescing preterm infants within the corrected age of 6 months, those who were exclusively breastfed showed increased intestinal inflammation mediated by neutrophils. Constipation moderately elevates the fecal calprotectin levels. Probiotics may serve as a protective factor against a lower degree of neutrophil-mediated intestinal inflammation. During early gastrointestinal development, long-term, low-grade, and safe inflammatory stimulation may be a positive factor for intestinal barrier development. Intestinal inflammation Premature Constipation Nutritional Support Probiotics Figures Figure 1 What is known? The breastfed neonatal preterm infants demonstrated elevated concentrations of fecal calprotectin that were beyond the reference range. No studies examining the association between constipation and fecal calprotectin have been published within the last five years. The impact of probiotic supplementation on fecal calprotectin for convalescing preterm infants remains uncertain. What is new ? Prolonged breastfeeding in convalescing preterm infants is associated with mildly elevated fecal calprotectin levels but within the reference range. The fecal calprotectin levels mildly elevated in constipated convalescing preterm infants compared with non-constipated infants. Probiotics may serve as a protective factor against neutrophil-mediated intestinal inflammation. Introduction Preterm infants (PTI) are neonates born at < 37 weeks’ gestation. Recent advancements in neonatal intensive care unit (NICU) management have significantly improved their survival [ 1 , 2 ]. The NICU provides 24/7 intensive monitoring and care for high-risk neonates (e.g., PTI, low-birth-weight infants, those with life-threatening conditions). Owing to immature organ systems, PTI face increased risks of severe infections, growth/developmental delays, metabolic disorders, and post-feeding gastrointestinal issues (e.g., vomiting, bloating, diarrhea, gastric retention) compared to full-term infants [ 1 – 3 ]. The first postnatal year is the critical window for catch-up growth [ 4 ], and such gastrointestinal complications may impair PTI survival and developmental catch-up [ 3 , 4 ]. Neonatal necrotizing enterocolitis (NEC), an acute early-life intestinal disorder, is more prevalent in PTI. It arises from intestinal bacterial invasion, inducing inflammation that may progress to intestinal wall necrosis or perforation [ 5 , 6 ]. Severe NEC carries a poor prognosis and impairs PTI growth/development [ 5 , 6 ]; while medical progress has improved NEC survival—with mild cases (managed medically) having favorable outcomes [ 5 ]—the long-term impact of treated mild NEC on PTI intestinal development remains unclear. Fecal calprotectin (FC), a neutrophil-derived protein, is a validated marker of intestinal inflammation, used in diagnosing inflammatory bowel disease, infectious enteritis, and functional gastrointestinal disorders [ 7 – 9 ]. FC levels surge pre- and during NEC episodes and may remain elevated until NICU discharge [ 5 , 6 ], but data on long-term FC fluctuations in NEC-affected infants are scarce. Fecal consistency is a key determinant of FC detection, with diarrheal stools having higher FC concentrations than formed stools [ 8 – 10 ]. Building on prior work on perinatal factors influencing FC in PTI [ 11 ], this study explores how neonatal hospital-related stressors and feeding practices affect FC during the neonatal period, and extends to convalescent PTI (10–18 months corrected age [CA]) to assess long-term implications. Preterm infants’ corrected age (CA) is the "equivalent full-term age" calculated as chronological age minus prematurity weeks. Cow’s milk protein allergy is associated with elevated FC and gastrointestinal symptoms (e.g., bloating, bloody stools, diarrhea) [ 12 , 13 ], and is linked to allergic rhinitis, atopic eczema, and respiratory allergies [ 14 , 15 ]. However, no studies have explored the association between allergic diathesis (e.g., rhinitis, atopic eczema, respiratory allergies) and FC. Thus, this study aims to identify factors influencing FC in convalescent PTI (10–18 months CA; defined as chronological age minus prematurity weeks). For the first time, it examines the long-term impact of NEC on FC and explores the association between allergic diathesis and FC in this cohort. We hypothesize that convalescent PTI with a history of neonatal NEC or allergic predisposition will have higher FC levels than those without NEC. Methods Ethics Statement The authors declare that this research adheres to the ethical principles outlined by the Ethics Committee, Suzhou Municipal Hospital (IRB approval No. K-2022-016-K02). All participants enrolled in this study provided written informed consent, which was obtained from their parents or legal guardians. All procedures involving human participants were conducted in accordance with the ethical principles outlined in the International Ethical Guidelines for Health-related Research Involving Humans issued by the Council for International Organizations of Medical Sciences (CIOMS) and the Declaration of Helsinki (1964), as revised in 2013. Subjects This study was designed as cross-sectional research. The recruitment of study participants was conducted from June 2024 to August 2024. Based on the number of subjects in relevant similar studies [ 10 – 13 , 16 – 17 ], a total of 133 PTI, with a gestational age under 37 weeks and at 10–18 months of CA, were randomly chosen at the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University. Two subjects with severe disabilities, malformations, chromosomal or genetic defects, three subjects whose mother had taken oral or intravenous antibiotics during breastfeeding, zero subjects whose mother had mastitis during breastfeeding, four subjects who had experienced diarrhea within one week before fecal sampling, and two of them received antibiotic treatment were excluded. Due to the absence of three fecal specimens, the final number analyzed was 109. Investigation methods and content During the recruitment period from June 2024 to August 2024, interviews and written questionnaires were administered, and medical record data were collected. Details, including date of birth, expected date of delivery, gestational age at birth (weeks), maternal gestational age (years), birth weight (gram), sex, days of hospitalization in the NICU at birth (days), and delivery type, were obtained from medical records. Compute the corrected age of PTI according to the expected date of delivery and express results in monthly increments. One week before stool sample collection, interviews and questionnaires were used to collect details about the timing of formula addition and cessation of breast milk, check for any history of neonatal NEC, rhinitis, eczema, and wheezing, antibiotic or probiotic use, and any gastrointestinal issues (diarrhea or constipation). Data collation and verification were conducted from September to October 2024. Regarding the 109 subjects, the number of missing cases for each data item was no more than 5% of 109. For missing continuous numerical variables, mean imputation was used to fill in the gaps. The number of participants with missing data for each variable of interest are shown in Table 1 . Table 1 The demographic and clinical features of the subjects (N = 109). Binary categorical variables n (%) Z P No. of missing Sex -1.203 0.229 a 0 Male 60 (55.0) Female 49 (45.0) Neonatal NEC -1.467 0.142 a 0 Yes 4 (3.7) No 105 (96.3) Add formula within 6 months -2.286 0.022* a 0 Yes 98 (89.9) No 11 (10.1) Stop breastfeeding within 6 months -0.605 0.545 a 0 Yes 67 (61.5) No 41 (37.6) Probiotic supplementation -1.541 0.123 a 0 Yes 22 (20.2) No 87 (79.8) Constipation -2.254 0.024* a 0 Yes 13 (11.9) No 96 (88.1) History of eczema -0.464 0.642 a 0 Yes 24 (22.0) No 85 (78.0) History of rhinitis -0.209 0.834 a 0 Yes 8 (7.3) No 101 (92.7) History of wheezing -0.435 0.664 a 0 Yes 14 (12.8) No 95 (87.2) FC grades (µg/g) - - - 60 (grade 3) 11 (10.1) Continuous variable factors M ± SD ρ P No. of missing Maternal gestational age (y) 31.56 ± 3.89 -0.016 0.866 b 3 Gestational age (wks) 31.95 ± 2.51 0.058 0.549 b 2 Days of hospital stay at birth (d) 38.65 ± 24.62 -0.134 0.164 b 3 *P<0.05* a Mann-Whitney U test. b Spearman's rank correlation. *NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit; 109 subjects born between 25 and 36 weeks of gestational age were analyzed in this research. Females constituted 55% of the subjects, and their mean birth weight was 1616.07 g (SD = 487.903). The mean birth weight of males was 1659.27 g (SD = 452.513). The exclusively breastfed infants within the first six months of CA exhibit higher FC content compared to their non-exclusively breastfed counterparts. Individuals with constipation demonstrate elevated FC content relative to those without constipation. No correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth and FC content. Sampling and detection methods of FC Fecal calprotectin measurements were performed between November 2024 and May 2025. Researchers collected around 5g of feces from each subject and placed it into a sample collection tube for preservation. After collection, the samples were kept at 2–8℃. They were sent to the Clinical Laboratory of Suzhou Hospital, affiliated with Nanjing Medical University, within 12 hours for testing. We distributed 122 fecal collection tubes and retrieved 109 of them. The calprotectin concentration in the fecal samples was measured by using the Diagnostic Kit (Colloidal Gold) for Calprotectin (Xiamen Wiz Biotech Co., Ltd.-- Xiamen City, Fujian Province, 361026, P.R. China). The upper reference limit for healthy adults provided by the manufacturer is 60µg/g, and the lower detection limit of the kit is 15µg/g. During data analysis, the content less than 15µg/g was randomly assigned values ranging from 0 to 14µg/g using Microsoft Excel. The FC content of the subjects was classified into three grades: 60µg/g. Statistical Analysis The data inspection and analysis were carried out between June and October 2025. SPSS 25.0 ( https://www.ibm.com/products/spss-statistics,RRID : SCR_016479) was used for data analysis. For dichotomous variables, such as sex, neonatal conditions, time of formula introduction, probiotic use, constipation, and a history of eczema, rhinitis, or wheezing, frequencies and percentages are used for descriptive purposes. The Mann-Whitney U test was used to examine their associations with FC content. The Chi-square test was chosen to analyze their correlation to FC grades. Fisher's exact test is recommended when the expected frequency in any cell of a contingency table is below five. The Spearman's rank correlation analysis was used to investigate the relationships between gestational weeks, maternal age at pregnancy, and FC content and grades. We used the Mann-Whitney U test to examine their links to FC grades. Statistical significance was considered when P < 0.05. Multiple linear regression was employed to analyze the relationship between relevant factors and the FC content. Ordinal Logistic regression was utilized to analyze the relationship between the factors and FC grades. The results are presented as regression coefficients (B), standard errors (SE), odds ratios (OR), and corresponding 95% confidence intervals (CI). An α level of 0.05 was set as the threshold for statistical significance. Results Characteristics of the subjects 133 subjects born between 25 and 36 weeks of gestational age were recruited, and 109 were finally analyzed. For details, please refer to the flowchart (Fig. 1 ). Females constituted 55% of the subjects (Table 1 ), and their mean birth weight was 1616.07 g (SD = 487.903). The mean birth weight of males was 1659.27 g (SD = 452.513). Other information about the subjects is as follows (Table 1 ). FC content detection 109 fecal samples were collected for the quantitative determination of FC. The average concentration was 37.63 ± 37.796 µg/g, ranging from < 15 to 213 µg/g. Influencing factors of FC in convalescing PTI No correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, or wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth, and FC content(P>0.05) (Table 1 ). Besides, no correlations were discovered between the above factors and FC grades (P>0.05) (Table 2 ). Table 2 The relationship between potential correlated factors and FC grades. Binary categorical variables χ² P Fisher’s P History of neonatal NEC 5.344 0.069a 0.101 b Formula addition time 4.850 0.088a 0.114 b Breastfeeding cessation time 2.197 0.333a - Probiotics supplementation 2.176 0.337a - Constipation 6.629 0.036*a 0.020* b History of eczema 1.785 0.410a - History of rhinitis 1.029 0.598a 0.868 b History of wheezing 2.250 0.325a 0.458 b Continuous variables ρ P Gestational age 0.091 0.346 c Maternal gestational age 0.033 0.735 c Days of hospital stay at birth -0.142 0.141 c *P<0.05* a Chi-square test. b Fisher’s exact tests. c Spearman's rank correlation. *NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit; No correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth and FC grades. The average content of FC in PTI who introduced formula milk powder within 6 months of CA was lower than that introduced after 6 months of CA (P = 0.022*) (Table 1 ). In another study of full-term infants conducted by our research team, such a difference was not observed (Table A1, Table A2). A significant difference was observed between the constipation and FC content (P = 0.024*) (Table 1 ) and grades (P = 0.020*) (Table 2 ). The FC content in the constipated group was relatively higher, but less than 60µg/g. The FC grade was also higher in the constipated group. Multiple linear regression was employed to analyze the relationship between the above factors and the FC content. PTI with symptoms of rhinitis, eczema, or wheezing were considered to have an allergic constitution. Based on the above results, we developed two models. Model 1 included only control variables for which no correlations were detected: timing of breastfeeding cessation, allergic constitution, number of days hospitalized in NICU at birth, gestational age, maternal age, probiotic supplementation, and the presence of neonatal NEC. Model 2 was built upon Model 1 by introducing two key independent variables: the timing of formula introduction and the presence of constipation. The model summary statistics indicated a significant improvement in explanatory power after the inclusion of the key independent variables. As shown in Model 1, the control variables were not statistically significant (F(7, 100) = 1.257, P = 0.279) and accounted for a negligible proportion of the variance in FC content (Adjusted R² = 0.017). In contrast, Model 2 was statistically significant (F(9, 98) = 2.562, P = 0.011*) and explained 11.6% of the variance (Adjusted R² = 0.116). The change in R² from Model 1 to Model 2 was 0.110, which was statistically significant (F Change (2, 98) = 6.631, P = 0.002**), indicating that the two additional variables collectively provided a significant incremental contribution to the model. The Durbin-Watson statistic of 1.918 suggested that the assumption of independent errors was met (Table 3 ). Table 3 Results of the multiple linear regression model. FC content B t P Tolerance VIF Model 1 Intercept 0.956 0.01 0.992 Breastfeeding cessation 8.359 1.082 0.282 0.934 1.071 Allergic constitution -11.044 -1.443 0.152 0.971 1.03 Days of the NICU 0.019 0.068 0.946 0.298 3.357 Gestational age 1.813 0.676 0.5 0.29 3.445 Maternal age -0.56 -0.585 0.56 0.955 1.048 Probiotic use -14.811 -1.547 0.125 0.914 1.094 History of NEC -16.853 -0.838 0.404 0.911 1.098 Model 2 Intercept -42.243 -0.464 0.644 Breastfeeding cessation 5.137 0.669 0.505 0.85 1.176 Allergic constitution -8.513 -1.163 0.248 0.955 1.047 Days of the NICU 0.159 0.599 0.551 0.292 3.429 Gestational age 2.537 0.993 0.323 0.287 3.479 Maternal age -0.282 -0.309 0.758 0.94 1.064 Probiotic use -14.747 -1.614 0.11 0.902 1.109 History of NEC -19.592 -1.015 0.312 0.889 1.125 Time of formula adding 27.613 2.257 0.026* 0.862 1.161 formula adding(Reference:≤6 M a ) - - - - - Constipation 31.905 2.81 0.006** 0.927 1.079 Constipation(Reference: No) - - - - - *P<0.05*, P<0.001**. *Model 1: F = 1.257, P = 0.279, Adjusted R 2 = 0.017; Model 2: F = 6.631, P = 0.011*, Adjusted R2 = 0.116. a Corrected age of 6 months. *NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit; Introduction of formula after 6 months was significantly associated with higher FC content (B = 27.613, P = 0.026*). The presence of constipation was a strong and significant positive predictor of FC content (B = 31.905, P = 0.006**). The Variance Inflation Factor (VIF) values were well below the threshold of 10 (range: 1.047–3.479). In Model 1, the control variables were not statistically significant (F(7, 100) = 1.257, P = 0.279) and accounted for a negligible proportion of the variance in FC content (Adjusted R² = 0.017). In contrast, Model 2 was statistically significant (F(9, 98) = 2.562, P = 0.011*) and explained 11.6% of the variance (Adjusted R² = 0.116). The Durbin-Watson statistic of 1.918 suggested that the assumption of independent errors was met. Analysis of the regression coefficients in Model 2 revealed that both primary independent variables were significant predictors of FC content. Introduction of formula after 6 months was significantly associated with higher FC content (B = 27.613, P = 0.026*). The presence of constipation was a strong and significant positive predictor of FC content (B = 31.905, P = 0.006**) (Table 3 ). None of the control variables included in Model 1 reached statistical significance in either model (all P > 0.05) (Table 3 ). Furthermore, collinearity statistics confirmed that multicollinearity was not a concern in the analysis, as all Variance Inflation Factor (VIF) values were well below the threshold of 10 (range: 1.047–3.479). In summary, the results demonstrate that later introduction of formula (> 6 months) and the presence of constipation are independent and significant factors associated with increased FC content in convalescing PTI, after controlling for relevant perinatal and clinical factors. In order to enhance the sensitivity of the analysis, the influencing factors listed were also included in the ordinal logistic regression model to examine the relationship between each factor and the FC grades. The results showed that the history of NEC, the timing of formula addition, probiotic supplementation, and constipation, and the FC grades (P < 0.05) (Table 4 ). Table 4 Results of the Ordinal logistic regression model. FC grades B SE P OR(95%CI) Maternal age 0.035 0.055 0.521 1.036(0.931, 1.154) Gestational age -0.047 0.151 0.753 0.954(0.709, 1.281) Days of the NICU -0.011 0.016 0.485 0.989(0.959, 1.020) Time of formula adding(≤ 6 M) -1.82 0.77 0.018* 0.162(0.036, 0.732) Time of formula adding(Reference:>6 M) - - - - Breastfeeding cessation(≤ 6 M) 0.483 0.457 0.291 1.621(0.661, 3.971) Breastfeeding cessation(Reference:>6 M) - - - - Probiotic use: No 1.152 0.539 0.032* 3.165(1.102, 9.096) Probiotic use (Reference: Yes) - - - - Constipation: No -1.831 0.722 0.011* 0.160(0.039, 0.659) Constipation (Reference: Yes) - - - - Allergic constitution: No 0.382 0.439 0.383 1.465(0.621, 3.462) Allergic constitution (Reference: Yes) - - - - History of NEC: No 2.94 1.334 0.028* 18.915(1.383, 259.105) *P<0.05* *NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit; The results showed the association between the history of NEC, the timing of formula addition, probiotic supplementation and constipation and the FC grades. The FC grades of PTI without constipation tended to be lower (OR = 0.160, 95% CI: 0.039, 0.659)(P = 0.011*). Starting formula milk powder supplementation earlier (≤ 6 months) resulted in lower FC grades than those who began later (> 6 months)(OR = 0.162, 95% CI: 0.036, 0.732)(P = 0.018*). Infants who did not receive probiotic supplementation had 3.165 times the risk of elevated FC grades compared to those who did (OR = 3.165, 95% CI: 1.102, 9.096)(P = 0.032*). In comparison to PTI with NEC during the neonatal period, the FC grades of PTI without NEC were higher (OR = 18.915, 95% CI: 1.383, 259.105)(P = 0.028*). It should be noted that the 95%CI of OR for NEC history is extremely wide, revealing a result of considerable uncertainty (Table 4 ). In conclusion, constipation is a crucial risk factor for the elevation of FC, and introducing formula before 6 months of CA is a protective factor for the increase of FC. These have been confirmed in both regression models. Administering probiotics may be a protective factor for a lower degree of FC. There is insufficient evidence to establish a relationship between a history of NEC and FC. Discussion The mean fecal calprotectin (FC) concentration in this study was lower than that reported in neonatal preterm infant (PTI) cohorts [ 16 , 17 ]. FC accumulates in fetal meconium (being highly degradation-resistant) and rises rapidly in the first postnatal week [ 11 ]; regional/ethnic differences or varied detection kits may also contribute to FC variability [ 9 , 11 , 18 ]. Constipation emerged as a risk factor for elevated FC content and grades. Few studies have explored this association, but a functional constipation study reported mean FC < 50 µg/g [ 18 ], consistent with our findings—indicating mild or subclinical neutrophil-mediated intestinal inflammation in constipation. Contrary to our hypothesis, formula introduction after 6 months corrected age (CA) was linked to higher FC. Late formula initiators rely primarily on breast milk, which contains gut microbiota [ 19 ] and inflammatory factors [ 11 ] that induce intestinal immune responses, increasing basal FC-associated inflammation. Breast milk promotes PTI intestinal barrier maturation [ 20 ], so we hypothesize that low-intensity, sustained, safe inflammatory stimuli during early gastrointestinal development may benefit barrier function—low-grade neutrophil-mediated inflammation is not inherently detrimental. While Mann-Whitney U, multiple linear regression, and Chi-square tests showed no correlation between probiotic use and FC, ordinal logistic regression revealed a significant association with reduced FC grades (not absolute values)—indicating probiotics exert grade-specific anti-inflammatory effects rather than linear reductions. This aligns with studies showing probiotics lowered FC in dermatitis-induced mice [ 21 ] and Bifidobacterium supplementation reduced FC in breastfed neonatal PTI [ 22 ]. Contrary to our hypothesis, PTI with a neonatal NEC history had lower FC grades at 10–18 months CA. However, only 4 NEC cases (vs. 105 non-NEC) were included, leading to a wide OR 95% CI (0.724, 259.105) and insufficient statistical power. While multivariable models identified NEC history as a FC grade predictor, this finding is preliminary and requires validation in large-scale prospective studies. No significant associations were found between FC and NICU hospitalization duration or allergic constitution. While U.S. research linked neonatal NICU-related pain/stress to early-life FC [ 11 ], our data suggest such intestinal stress responses diminish over time with environmental changes. Prior studies linked allergic enteritis/cow’s milk protein allergy to higher FC [ 23 ], but our cohort had mild, early-stage allergic symptoms (no overt food intolerance), explaining the lack of correlation. Future studies could stratify by allergy severity or include older children to explore this association. In addition, the findings of that the FC grades of PTI with a history of neonatal NEC were lower than those of the non-NEC group at 10–18 months CA. This result was also contrary to our research hypothesis. It should be noted that only four subjects with a history of neonatal NEC, compared with 105 non-NEC PTI, were included in this re-search. Although the multivariable model recognized a history of neonatal NEC as a potent predictor of FC grades, this finding should be interpreted with prudence. The small sample size resulted in a wide 95% CI for OR (0.724, 259.105). This might lead to insufficient statistical power of the results. Consequently, the strength of the association between a history of neonatal NEC and FC grades requires verification in a prospective study with a larger sample size. This study did not find a significant influence of the number of neonatal hospitalization days in NICU and allergic constitution on the FC content. A study from the United States indicated that the cumulative pain/stress endured by PTI during their NICU hospitalization might affect the FC content in early life [ 11 ]. Nevertheless, it did not focus on the long-term impact of that factor on FC. Our research indicated that the intestinal stress response from early life may diminish over time due to environmental changes. Previous studies suggest that children with allergic enteritis and cow's milk protein allergy tend to have higher intestinal inflammation markers (FC) [ 23 ]. In this research, the participants predominantly had mild eczema and rhinitis. They were young and did not display clear signs of food intolerance. Consequently, no correlation was detected between allergic constitution and FC. Stratification of subjects by allergy severity or inclusion of older children may be considered to further investigate the potential association. Conclusions Formula supplementation timing influences neutrophil-mediated intestinal inflammation in convalescent preterm infants. Constipation induces a mild elevation of fecal calprotectin (FC) that does not exceed the upper detection limit. Probiotics exert a stronger effect on improving FC categorical grades than on reducing its linear measured values. Evidence is insufficient to confirm an association between neonatal necrotizing enterocolitis (NEC) history and FC in convalescent preterm infants. No significant correlations were observed between FC (content or grades) and sex, gestational age, maternal age at pregnancy, NICU stay duration, breastfeeding cessation timing, or allergic diathesis in this cohort. Abbreviations CA: corrected age; FC: fecal calprotectin; ICU: Neonatal Intensive Care Unit; NEC: necrotizing enterocolitis; PTI: Preterm infants. Declarations Acknowledgements The author wishes to extend sincere gratitude to the participating infants and their parents, as well as the medical staff and workers in the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University, and Suzhou Maternal and Child Healthcare Hospital. In particular, Dr Lu Xiaoting, Dr Li Beiquan, and Dr Pan Qiuping. Additionally, we extend our gratitude to the Clinical Laboratory of Suzhou Hospital Affiliated to Nanjing Medical University for their contributions to specimen testing, and especially to Prof. Chen Yan for inspecting the fecal specimens. Our gratitude also goes to Guo Yi for the help with specimen collection. We also thank Dr Chen Yiyuan, M.M., a public health expert, for her key contributions. She handled quality control and conducted a review of the statistical data. 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Yılmaz Topal, İ. Turgay Yağmur and E. Dibek Mısırlıoğlu, Postgraduate medicine. 2025, 137, 416 C. Rougé, M. J. Butel, H. Piloquet, L. Ferraris, A. Legrand, M. Vodovar, M. Voyer, M. F. de la Cochetière, D. Darmaun and J. C. Rozé, PloS one. 2010, 5, e11083 R. Hannawayya, R. Puentes, N. Mirzadzare, K. Cirone, H. Amin, A. Soraisham, B. Alshaikh, S. Thomas and E. R. Cobo, Pediatric research. 2025, 98, 278 F. E. Mahjoub, N. Zahedi, B. Ashjai, M. T. Ashtiani, F. Farahmand, M. Monajemzadeh, L. Kashi and H. Iranikhah, The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi. 2013, 62, 288 A. Zhernakova, M. Yassour, L. J. Hall and M. C. Collado, Cell host & microbe. 2025, 33, 820 L. Roskes, A. Chamzas, B. Ma, A. E. Medina, M. Gopalakrishnan, R. M. Viscardi and S. Sundararajan, Pediatric research. 2025, 97, 2065 M. J. Kim, J. Y. Kim, M. Kang, M. H. Won, S. H. Hong and Y. Her, International journal of molecular sciences. 2020, 21, J. A. Larke, K. Kuhn-Riordon, D. H. Taft, K. Sohn, S. Iqbal, M. A. Underwood, D. A. Mills and C. M. Slupsky, Journal of pediatric gastroenterology and nutrition. 2022, 75, 535 G. Czaja-Bulsa, K. Bulsa, M. Łokieć and A. Drozd, Nutrients. 2024, 16, Additional Declarations No competing interests reported. Supplementary Files Supplementaryfiles.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8459794","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":570603481,"identity":"af1abef6-10ab-402a-8cca-657c245e1a2a","order_by":0,"name":"Yaqi Liu","email":"","orcid":"","institution":"Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yaqi","middleName":"","lastName":"Liu","suffix":""},{"id":570603483,"identity":"18d0c8ef-3adb-4ffa-8bc4-80c6d1f16718","order_by":1,"name":"Kan Ye","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvUlEQVRIiWNgGAWjYFACNiA2kODhZ2Y+/IAELRU2MpLtbGkGJGg5k2ZjcJ5HQYIoDQbH2xI/F7Yd5jE+zMNgwFBjE01Yy5ljh6VnArWYHeY98IDhWFpuA0EtN9IbpHnBWvgSDBgbDhOh5f7z5t8gLcbNPAYSxGm5wXZMmudMGo8BM7FaJM+kpVnzVNjwSBwGBnICMX7hO37M+DbQfHv+/sOHH3yosSGsReEAMi+BkHIQkCdo6CgYBaNgFIwCAB0yPZfI30aEAAAAAElFTkSuQmCC","orcid":"","institution":"Suzhou Hospital Affiliated to Nanjing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Kan","middleName":"","lastName":"Ye","suffix":""}],"badges":[],"createdAt":"2025-12-27 08:53:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8459794/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8459794/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99859845,"identity":"5cd5619e-ebe1-4f22-9c98-72da428190fc","added_by":"auto","created_at":"2026-01-09 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06:39:42","extension":"xml","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":99092,"visible":true,"origin":"","legend":"","description":"","filename":"f0a0c5c5c7c74104b992459f75fd50011structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8459794/v1/c3e4c974be64a38807078ebd.xml"},{"id":99859844,"identity":"b2310037-3adb-44f8-b9a0-9ebb9fe3bc51","added_by":"auto","created_at":"2026-01-09 06:39:34","extension":"html","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":110005,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8459794/v1/7b4cd9063c8aed4a0771b55a.html"},{"id":100357687,"identity":"46c8e088-4ab2-4efe-b9d9-cbf8068899ec","added_by":"auto","created_at":"2026-01-16 07:20:10","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":153428,"visible":true,"origin":"","legend":"\u003cp\u003eThe flow diagram.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8459794/v1/b1ab44d5a8dec3bfc3098119.png"},{"id":101446059,"identity":"b1d1bcb8-57f6-43ff-ab9f-cd7a54857e15","added_by":"auto","created_at":"2026-01-29 18:25:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1120259,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8459794/v1/28a15ef9-a4c8-4ba8-8588-35712c126cf4.pdf"},{"id":99859864,"identity":"f8303280-523e-4b59-add6-acc8180a9441","added_by":"auto","created_at":"2026-01-09 06:39:41","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":17585,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryfiles.docx","url":"https://assets-eu.researchsquare.com/files/rs-8459794/v1/ad819a59d2586254343aca4c.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Landscape of Influential Factors on Fecal Calprotectin in Convalescing Preterm Infants (Corrected Age of 10-18 Months)","fulltext":[{"header":"What is known?","content":"\u003cul\u003e\n \u003cli\u003eThe breastfed neonatal preterm infants demonstrated elevated concentrations of fecal calprotectin that were beyond the reference range.\u003c/li\u003e\n \u003cli\u003eNo studies examining the association between constipation and fecal calprotectin have been published within the last five years.\u003c/li\u003e\n \u003cli\u003eThe impact of probiotic supplementation on fecal calprotectin for convalescing preterm infants remains uncertain.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhat\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eis new\u003c/strong\u003e\u003cstrong\u003e?\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eProlonged breastfeeding in convalescing preterm infants is associated with mildly elevated fecal calprotectin levels but within the reference range.\u003c/li\u003e\n \u003cli\u003eThe fecal calprotectin levels mildly elevated in constipated convalescing preterm infants compared with non-constipated infants.\u003c/li\u003e\n \u003cli\u003eProbiotics may serve as a protective factor against neutrophil-mediated intestinal inflammation.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Introduction","content":"\u003cp\u003ePreterm infants (PTI) are neonates born at \u0026lt;\u0026thinsp;37 weeks\u0026rsquo; gestation. Recent advancements in neonatal intensive care unit (NICU) management have significantly improved their survival [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The NICU provides 24/7 intensive monitoring and care for high-risk neonates (e.g., PTI, low-birth-weight infants, those with life-threatening conditions). Owing to immature organ systems, PTI face increased risks of severe infections, growth/developmental delays, metabolic disorders, and post-feeding gastrointestinal issues (e.g., vomiting, bloating, diarrhea, gastric retention) compared to full-term infants [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The first postnatal year is the critical window for catch-up growth [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and such gastrointestinal complications may impair PTI survival and developmental catch-up [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNeonatal necrotizing enterocolitis (NEC), an acute early-life intestinal disorder, is more prevalent in PTI. It arises from intestinal bacterial invasion, inducing inflammation that may progress to intestinal wall necrosis or perforation [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Severe NEC carries a poor prognosis and impairs PTI growth/development [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]; while medical progress has improved NEC survival\u0026mdash;with mild cases (managed medically) having favorable outcomes [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u0026mdash;the long-term impact of treated mild NEC on PTI intestinal development remains unclear.\u003c/p\u003e \u003cp\u003eFecal calprotectin (FC), a neutrophil-derived protein, is a validated marker of intestinal inflammation, used in diagnosing inflammatory bowel disease, infectious enteritis, and functional gastrointestinal disorders [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. FC levels surge pre- and during NEC episodes and may remain elevated until NICU discharge [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], but data on long-term FC fluctuations in NEC-affected infants are scarce.\u003c/p\u003e \u003cp\u003eFecal consistency is a key determinant of FC detection, with diarrheal stools having higher FC concentrations than formed stools [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Building on prior work on perinatal factors influencing FC in PTI [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], this study explores how neonatal hospital-related stressors and feeding practices affect FC during the neonatal period, and extends to convalescent PTI (10\u0026ndash;18 months corrected age [CA]) to assess long-term implications. Preterm infants\u0026rsquo; corrected age (CA) is the \"equivalent full-term age\" calculated as chronological age minus prematurity weeks.\u003c/p\u003e \u003cp\u003eCow\u0026rsquo;s milk protein allergy is associated with elevated FC and gastrointestinal symptoms (e.g., bloating, bloody stools, diarrhea) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], and is linked to allergic rhinitis, atopic eczema, and respiratory allergies [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, no studies have explored the association between allergic diathesis (e.g., rhinitis, atopic eczema, respiratory allergies) and FC.\u003c/p\u003e \u003cp\u003eThus, this study aims to identify factors influencing FC in convalescent PTI (10\u0026ndash;18 months CA; defined as chronological age minus prematurity weeks). For the first time, it examines the long-term impact of NEC on FC and explores the association between allergic diathesis and FC in this cohort. We hypothesize that convalescent PTI with a history of neonatal NEC or allergic predisposition will have higher FC levels than those without NEC.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eEthics Statement\u003c/h2\u003e \u003cp\u003eThe authors declare that this research adheres to the ethical principles outlined by the \u003cem\u003eEthics Committee, Suzhou Municipal Hospital\u003c/em\u003e (IRB approval No. K-2022-016-K02). All participants enrolled in this study provided written informed consent, which was obtained from their parents or legal guardians. All procedures involving human participants were conducted in accordance with the ethical principles outlined in the \u003cem\u003eInternational Ethical Guidelines for Health-related Research Involving Humans\u003c/em\u003e issued by the Council for International Organizations of Medical Sciences (CIOMS) and the Declaration of Helsinki (1964), as revised in 2013.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSubjects\u003c/h3\u003e\n\u003cp\u003eThis study was designed as cross-sectional research. The recruitment of study participants was conducted from June 2024 to August 2024. Based on the number of subjects in relevant similar studies [\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], a total of 133 PTI, with a gestational age under 37 weeks and at 10\u0026ndash;18 months of CA, were randomly chosen at the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University. Two subjects with severe disabilities, malformations, chromosomal or genetic defects, three subjects whose mother had taken oral or intravenous antibiotics during breastfeeding, zero subjects whose mother had mastitis during breastfeeding, four subjects who had experienced diarrhea within one week before fecal sampling, and two of them received antibiotic treatment were excluded. Due to the absence of three fecal specimens, the final number analyzed was 109.\u003c/p\u003e\n\u003ch3\u003eInvestigation methods and content\u003c/h3\u003e\n\u003cp\u003eDuring the recruitment period from June 2024 to August 2024, interviews and written questionnaires were administered, and medical record data were collected. Details, including date of birth, expected date of delivery, gestational age at birth (weeks), maternal gestational age (years), birth weight (gram), sex, days of hospitalization in the NICU at birth (days), and delivery type, were obtained from medical records. Compute the corrected age of PTI according to the expected date of delivery and express results in monthly increments. One week before stool sample collection, interviews and questionnaires were used to collect details about the timing of formula addition and cessation of breast milk, check for any history of neonatal NEC, rhinitis, eczema, and wheezing, antibiotic or probiotic use, and any gastrointestinal issues (diarrhea or constipation). Data collation and verification were conducted from September to October 2024. Regarding the 109 subjects, the number of missing cases for each data item was no more than 5% of 109. For missing continuous numerical variables, mean imputation was used to fill in the gaps. The number of participants with missing data for each variable of interest are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe demographic and clinical features of the subjects (N\u0026thinsp;=\u0026thinsp;109).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBinary categorical variables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eZ\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo. of missing\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.203\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.229\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60 (55.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49 (45.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNeonatal NEC\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.467\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.142\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (3.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e105 (96.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdd formula within 6 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.022*\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e98 (89.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (10.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStop breastfeeding within 6 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.545\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67 (61.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41 (37.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eProbiotic supplementation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.541\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.123\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (20.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87 (79.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eConstipation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.254\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.024*\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (11.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96 (88.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistory of eczema\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.464\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.642\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (22.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e85 (78.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistory of rhinitis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.209\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.834\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (7.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e101 (92.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistory of wheezing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.435\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.664\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (12.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95 (87.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFC grades (\u0026micro;g/g)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;15 (grade 1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28 (25.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15 to 60 (grade 2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70 (64.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;60 (grade 3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (10.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eContinuous variable factors\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eM\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eρ\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eP\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eNo. of missing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMaternal gestational age (y)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31.56\u0026thinsp;\u0026plusmn;\u0026thinsp;3.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.866\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGestational age (wks)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31.95\u0026thinsp;\u0026plusmn;\u0026thinsp;2.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.549\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDays of hospital stay at birth (d)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38.65\u0026thinsp;\u0026plusmn;\u0026thinsp;24.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.134\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.164\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*P\u0026lt;0.05*\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e Mann-Whitney U test.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003eb\u003c/sup\u003e Spearman's rank correlation.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit;\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e109 subjects born between 25 and 36 weeks of gestational age were analyzed in this research. Females constituted 55% of the subjects, and their mean birth weight was 1616.07 g (SD\u0026thinsp;=\u0026thinsp;487.903). The mean birth weight of males was 1659.27 g (SD\u0026thinsp;=\u0026thinsp;452.513).\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eThe exclusively breastfed infants within the first six months of CA exhibit higher FC content compared to their non-exclusively breastfed counterparts. Individuals with constipation demonstrate elevated FC content relative to those without constipation.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNo correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth and FC content.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eSampling and detection methods of FC\u003c/h3\u003e\n\u003cp\u003eFecal calprotectin measurements were performed between November 2024 and May 2025. Researchers collected around 5g of feces from each subject and placed it into a sample collection tube for preservation. After collection, the samples were kept at 2\u0026ndash;8℃. They were sent to the Clinical Laboratory of Suzhou Hospital, affiliated with Nanjing Medical University, within 12 hours for testing. We distributed 122 fecal collection tubes and retrieved 109 of them. The calprotectin concentration in the fecal samples was measured by using the Diagnostic Kit (Colloidal Gold) for Calprotectin (Xiamen Wiz Biotech Co., Ltd.-- Xiamen City, Fujian Province, 361026, P.R. China). The upper reference limit for healthy adults provided by the manufacturer is 60\u0026micro;g/g, and the lower detection limit of the kit is 15\u0026micro;g/g. During data analysis, the content less than 15\u0026micro;g/g was randomly assigned values ranging from 0 to 14\u0026micro;g/g using Microsoft Excel. The FC content of the subjects was classified into three grades: \u0026lt; 15\u0026micro;g/g, 15\u0026ndash;60\u0026micro;g/g/g, and \u0026gt;\u0026thinsp;60\u0026micro;g/g.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe data inspection and analysis were carried out between June and October 2025. SPSS 25.0 (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ibm.com/products/spss-statistics,RRID\u003c/span\u003e\u003cspan address=\"https://www.ibm.com/products/spss-statistics,RRID\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e: SCR_016479) was used for data analysis. For dichotomous variables, such as sex, neonatal conditions, time of formula introduction, probiotic use, constipation, and a history of eczema, rhinitis, or wheezing, frequencies and percentages are used for descriptive purposes. The Mann-Whitney U test was used to examine their associations with FC content. The Chi-square test was chosen to analyze their correlation to FC grades. Fisher's exact test is recommended when the expected frequency in any cell of a contingency table is below five. The Spearman's rank correlation analysis was used to investigate the relationships between gestational weeks, maternal age at pregnancy, and FC content and grades. We used the Mann-Whitney U test to examine their links to FC grades. Statistical significance was considered when P\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Multiple linear regression was employed to analyze the relationship between relevant factors and the FC content. Ordinal Logistic regression was utilized to analyze the relationship between the factors and FC grades. The results are presented as regression coefficients (B), standard errors (SE), odds ratios (OR), and corresponding 95% confidence intervals (CI). An α level of 0.05 was set as the threshold for statistical significance.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003eCharacteristics of the subjects\u003c/h2\u003e\n \u003cp\u003e133 subjects born between 25 and 36 weeks of gestational age were recruited, and 109 were finally analyzed. For details, please refer to the flowchart (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Females constituted 55% of the subjects (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e), and their mean birth weight was 1616.07 g (SD\u0026thinsp;=\u0026thinsp;487.903). The mean birth weight of males was 1659.27 g (SD\u0026thinsp;=\u0026thinsp;452.513). Other information about the subjects is as follows (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eFC content detection\u003c/h3\u003e\n\u003cp\u003e109 fecal samples were collected for the quantitative determination of FC. The average concentration was 37.63\u0026thinsp;\u0026plusmn;\u0026thinsp;37.796 \u0026micro;g/g, ranging from \u0026lt;\u0026thinsp;15 to 213 \u0026micro;g/g.\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eInfluencing factors of FC in convalescing PTI\u003c/h2\u003e\n \u003cp\u003eNo correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, or wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth, and FC content(P\u0026gt;0.05) (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Besides, no correlations were discovered between the above factors and FC grades (P\u0026gt;0.05) (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe relationship between potential correlated factors and FC grades.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eBinary categorical variables\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026chi;\u0026sup2;\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFisher\u0026rsquo;s P\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of neonatal NEC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.344\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.069a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.101\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFormula addition time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.850\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.088a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.114\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreastfeeding cessation time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.197\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.333a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eProbiotics supplementation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.337a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConstipation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.629\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.036*a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.020*\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of eczema\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.785\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.410a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of rhinitis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.029\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.598a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.868\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of wheezing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.325a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.458\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eContinuous variables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026rho;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGestational age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.091\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.346\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMaternal gestational age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.033\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.735\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDays of hospital stay at birth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.141\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e*P\u0026lt;0.05*\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e\u003csup\u003ea\u003c/sup\u003e Chi-square test.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e\u003csup\u003eb\u003c/sup\u003e Fisher\u0026rsquo;s exact tests.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e\u003csup\u003ec\u003c/sup\u003e Spearman\u0026apos;s rank correlation.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003e*NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003eNo correlations were discovered between sex, history of NEC, timing of breastfeeding cessation, probiotic intake, history of eczema, rhinitis, wheezing, gestational age, maternal gestational age, number of days hospitalized in the NICU at birth and FC grades.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eThe average content of FC in PTI who introduced formula milk powder within 6 months of CA was lower than that introduced after 6 months of CA (P\u0026thinsp;=\u0026thinsp;0.022*) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). In another study of full-term infants conducted by our research team, such a difference was not observed (Table A1, Table A2). A significant difference was observed between the constipation and FC content (P\u0026thinsp;=\u0026thinsp;0.024*) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e) and grades (P\u0026thinsp;=\u0026thinsp;0.020*) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). The FC content in the constipated group was relatively higher, but less than 60\u0026micro;g/g. The FC grade was also higher in the constipated group.\u003c/p\u003e\n \u003cp\u003eMultiple linear regression was employed to analyze the relationship between the above factors and the FC content. PTI with symptoms of rhinitis, eczema, or wheezing were considered to have an allergic constitution. Based on the above results, we developed two models. Model 1 included only control variables for which no correlations were detected: timing of breastfeeding cessation, allergic constitution, number of days hospitalized in NICU at birth, gestational age, maternal age, probiotic supplementation, and the presence of neonatal NEC. Model 2 was built upon Model 1 by introducing two key independent variables: the timing of formula introduction and the presence of constipation.\u003c/p\u003e\n \u003cp\u003eThe model summary statistics indicated a significant improvement in explanatory power after the inclusion of the key independent variables. As shown in Model 1, the control variables were not statistically significant (F(7, 100)\u0026thinsp;=\u0026thinsp;1.257, P\u0026thinsp;=\u0026thinsp;0.279) and accounted for a negligible proportion of the variance in FC content (Adjusted R\u0026sup2; = 0.017). In contrast, Model 2 was statistically significant (F(9, 98)\u0026thinsp;=\u0026thinsp;2.562, P\u0026thinsp;=\u0026thinsp;0.011*) and explained 11.6% of the variance (Adjusted R\u0026sup2; = 0.116). The change in R\u0026sup2; from Model 1 to Model 2 was 0.110, which was statistically significant (F Change (2, 98)\u0026thinsp;=\u0026thinsp;6.631, P\u0026thinsp;=\u0026thinsp;0.002**), indicating that the two additional variables collectively provided a significant incremental contribution to the model. The Durbin-Watson statistic of 1.918 suggested that the assumption of independent errors was met (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults of the multiple linear regression model.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"7\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eFC content\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTolerance\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVIF\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eModel 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntercept\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.956\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.992\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreastfeeding cessation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.359\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.282\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.934\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.071\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAllergic constitution\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-11.044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.443\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.152\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.971\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDays of the NICU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.946\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.298\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.357\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGestational age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.813\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.676\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.445\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMaternal age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.585\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.955\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.048\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eProbiotic use\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-14.811\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.547\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.914\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.094\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of NEC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-16.853\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.838\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.404\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.911\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.098\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eModel 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntercept\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-42.243\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.464\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.644\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreastfeeding cessation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.137\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.669\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.505\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.176\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAllergic constitution\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-8.513\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.163\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.248\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.955\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.047\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDays of the NICU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.159\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.599\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.551\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.292\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.429\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGestational age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.537\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.993\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.323\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.287\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.479\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMaternal age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.282\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.309\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.758\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.064\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eProbiotic use\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-14.747\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.614\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.902\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.109\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of NEC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-19.592\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.015\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.312\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.889\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.125\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTime of formula adding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.613\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.257\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.026*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.862\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.161\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eformula adding(Reference:\u0026le;6 M\u003csup\u003ea\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConstipation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31.905\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.006**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.927\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.079\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConstipation(Reference: No)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e*P\u0026lt;0.05*, P\u0026lt;0.001**.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e*Model 1: F\u0026thinsp;=\u0026thinsp;1.257, P\u0026thinsp;=\u0026thinsp;0.279, Adjusted R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.017; Model 2: F\u0026thinsp;=\u0026thinsp;6.631, P\u0026thinsp;=\u0026thinsp;0.011*, Adjusted R2\u0026thinsp;=\u0026thinsp;0.116.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e\u003csup\u003ea\u003c/sup\u003e Corrected age of 6 months.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e*NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eIntroduction of formula after 6 months was significantly associated with higher FC content (B\u0026thinsp;=\u0026thinsp;27.613, P\u0026thinsp;=\u0026thinsp;0.026*). The presence of constipation was a strong and significant positive predictor of FC content (B\u0026thinsp;=\u0026thinsp;31.905, P\u0026thinsp;=\u0026thinsp;0.006**). The Variance Inflation Factor (VIF) values were well below the threshold of 10 (range: 1.047\u0026ndash;3.479).\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eIn Model 1, the control variables were not statistically significant (F(7, 100)\u0026thinsp;=\u0026thinsp;1.257, P\u0026thinsp;=\u0026thinsp;0.279) and accounted for a negligible proportion of the variance in FC content (Adjusted R\u0026sup2; = 0.017). In contrast, Model 2 was statistically significant (F(9, 98)\u0026thinsp;=\u0026thinsp;2.562, P\u0026thinsp;=\u0026thinsp;0.011*) and explained 11.6% of the variance (Adjusted R\u0026sup2; = 0.116). The Durbin-Watson statistic of 1.918 suggested that the assumption of independent errors was met.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eAnalysis of the regression coefficients in Model 2 revealed that both primary independent variables were significant predictors of FC content. Introduction of formula after 6 months was significantly associated with higher FC content (B\u0026thinsp;=\u0026thinsp;27.613, P\u0026thinsp;=\u0026thinsp;0.026*). The presence of constipation was a strong and significant positive predictor of FC content (B\u0026thinsp;=\u0026thinsp;31.905, P\u0026thinsp;=\u0026thinsp;0.006**) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eNone of the control variables included in Model 1 reached statistical significance in either model (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Furthermore, collinearity statistics confirmed that multicollinearity was not a concern in the analysis, as all Variance Inflation Factor (VIF) values were well below the threshold of 10 (range: 1.047\u0026ndash;3.479).\u003c/p\u003e\n \u003cp\u003eIn summary, the results demonstrate that later introduction of formula (\u0026gt;\u0026thinsp;6 months) and the presence of constipation are independent and significant factors associated with increased FC content in convalescing PTI, after controlling for relevant perinatal and clinical factors.\u003c/p\u003e\n \u003cp\u003eIn order to enhance the sensitivity of the analysis, the influencing factors listed were also included in the ordinal logistic regression model to examine the relationship between each factor and the FC grades. The results showed that the history of NEC, the timing of formula addition, probiotic supplementation, and constipation, and the FC grades (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eResults of the Ordinal logistic regression model.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFC grades\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSE\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOR(95%CI)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMaternal age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.055\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.521\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.036(0.931, 1.154)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGestational age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.047\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.151\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.753\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.954(0.709, 1.281)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDays of the NICU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.485\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.989(0.959, 1.020)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTime of formula adding(\u0026le;\u0026thinsp;6 M)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.018*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.162(0.036, 0.732)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTime of formula adding(Reference:\u0026gt;6 M)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreastfeeding cessation(\u0026le;\u0026thinsp;6 M)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.483\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.457\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.291\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.621(0.661, 3.971)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBreastfeeding cessation(Reference:\u0026gt;6 M)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eProbiotic use: No\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.152\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.539\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.032*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.165(1.102, 9.096)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eProbiotic use (Reference: Yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConstipation: No\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.831\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.722\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.011*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.160(0.039, 0.659)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConstipation (Reference: Yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAllergic constitution: No\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.382\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.439\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.383\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.465(0.621, 3.462)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAllergic constitution (Reference: Yes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHistory of NEC: No\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.334\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.028*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.915(1.383, 259.105)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003e*P\u0026lt;0.05*\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003e*NEC: necrotizing enterocolitis; FC: fecal calprotectin; CA: corrected age; NICU: Neonatal Intensive Care Unit;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003eThe results showed the association between the history of NEC, the timing of formula addition, probiotic supplementation and constipation and the FC grades.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eThe FC grades of PTI without constipation tended to be lower (OR\u0026thinsp;=\u0026thinsp;0.160, 95% CI: 0.039, 0.659)(P\u0026thinsp;=\u0026thinsp;0.011*). Starting formula milk powder supplementation earlier (\u0026le;\u0026thinsp;6 months) resulted in lower FC grades than those who began later (\u0026gt;\u0026thinsp;6 months)(OR\u0026thinsp;=\u0026thinsp;0.162, 95% CI: 0.036, 0.732)(P\u0026thinsp;=\u0026thinsp;0.018*). Infants who did not receive probiotic supplementation had 3.165 times the risk of elevated FC grades compared to those who did (OR\u0026thinsp;=\u0026thinsp;3.165, 95% CI: 1.102, 9.096)(P\u0026thinsp;=\u0026thinsp;0.032*). In comparison to PTI with NEC during the neonatal period, the FC grades of PTI without NEC were higher (OR\u0026thinsp;=\u0026thinsp;18.915, 95% CI: 1.383, 259.105)(P\u0026thinsp;=\u0026thinsp;0.028*). It should be noted that the 95%CI of OR for NEC history is extremely wide, revealing a result of considerable uncertainty (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eIn conclusion, constipation is a crucial risk factor for the elevation of FC, and introducing formula before 6 months of CA is a protective factor for the increase of FC. These have been confirmed in both regression models. Administering probiotics may be a protective factor for a lower degree of FC. There is insufficient evidence to establish a relationship between a history of NEC and FC.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe mean fecal calprotectin (FC) concentration in this study was lower than that reported in neonatal preterm infant (PTI) cohorts [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. FC accumulates in fetal meconium (being highly degradation-resistant) and rises rapidly in the first postnatal week [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]; regional/ethnic differences or varied detection kits may also contribute to FC variability [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConstipation emerged as a risk factor for elevated FC content and grades. Few studies have explored this association, but a functional constipation study reported mean FC\u0026thinsp;\u0026lt;\u0026thinsp;50 \u0026micro;g/g [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], consistent with our findings\u0026mdash;indicating mild or subclinical neutrophil-mediated intestinal inflammation in constipation.\u003c/p\u003e \u003cp\u003eContrary to our hypothesis, formula introduction after 6 months corrected age (CA) was linked to higher FC. Late formula initiators rely primarily on breast milk, which contains gut microbiota [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] and inflammatory factors [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] that induce intestinal immune responses, increasing basal FC-associated inflammation. Breast milk promotes PTI intestinal barrier maturation [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], so we hypothesize that low-intensity, sustained, safe inflammatory stimuli during early gastrointestinal development may benefit barrier function\u0026mdash;low-grade neutrophil-mediated inflammation is not inherently detrimental.\u003c/p\u003e \u003cp\u003eWhile Mann-Whitney U, multiple linear regression, and Chi-square tests showed no correlation between probiotic use and FC, ordinal logistic regression revealed a significant association with reduced FC grades (not absolute values)\u0026mdash;indicating probiotics exert grade-specific anti-inflammatory effects rather than linear reductions. This aligns with studies showing probiotics lowered FC in dermatitis-induced mice [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and \u003cem\u003eBifidobacterium\u003c/em\u003e supplementation reduced FC in breastfed neonatal PTI [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eContrary to our hypothesis, PTI with a neonatal NEC history had lower FC grades at 10\u0026ndash;18 months CA. However, only 4 NEC cases (vs. 105 non-NEC) were included, leading to a wide OR 95% CI (0.724, 259.105) and insufficient statistical power. While multivariable models identified NEC history as a FC grade predictor, this finding is preliminary and requires validation in large-scale prospective studies.\u003c/p\u003e \u003cp\u003eNo significant associations were found between FC and NICU hospitalization duration or allergic constitution. While U.S. research linked neonatal NICU-related pain/stress to early-life FC [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], our data suggest such intestinal stress responses diminish over time with environmental changes. Prior studies linked allergic enteritis/cow\u0026rsquo;s milk protein allergy to higher FC [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], but our cohort had mild, early-stage allergic symptoms (no overt food intolerance), explaining the lack of correlation. Future studies could stratify by allergy severity or include older children to explore this association.\u003c/p\u003e \u003cp\u003eIn addition, the findings of that the FC grades of PTI with a history of neonatal NEC were lower than those of the non-NEC group at 10\u0026ndash;18 months CA. This result was also contrary to our research hypothesis. It should be noted that only four subjects with a history of neonatal NEC, compared with 105 non-NEC PTI, were included in this re-search. Although the multivariable model recognized a history of neonatal NEC as a potent predictor of FC grades, this finding should be interpreted with prudence. The small sample size resulted in a wide 95% CI for OR (0.724, 259.105). This might lead to insufficient statistical power of the results. Consequently, the strength of the association between a history of neonatal NEC and FC grades requires verification in a prospective study with a larger sample size.\u003c/p\u003e \u003cp\u003eThis study did not find a significant influence of the number of neonatal hospitalization days in NICU and allergic constitution on the FC content. A study from the United States indicated that the cumulative pain/stress endured by PTI during their NICU hospitalization might affect the FC content in early life [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Nevertheless, it did not focus on the long-term impact of that factor on FC. Our research indicated that the intestinal stress response from early life may diminish over time due to environmental changes.\u003c/p\u003e \u003cp\u003ePrevious studies suggest that children with allergic enteritis and cow's milk protein allergy tend to have higher intestinal inflammation markers (FC) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In this research, the participants predominantly had mild eczema and rhinitis. They were young and did not display clear signs of food intolerance. Consequently, no correlation was detected between allergic constitution and FC. Stratification of subjects by allergy severity or inclusion of older children may be considered to further investigate the potential association.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eFormula supplementation timing influences neutrophil-mediated intestinal inflammation in convalescent preterm infants. Constipation induces a mild elevation of fecal calprotectin (FC) that does not exceed the upper detection limit. Probiotics exert a stronger effect on improving FC categorical grades than on reducing its linear measured values. Evidence is insufficient to confirm an association between neonatal necrotizing enterocolitis (NEC) history and FC in convalescent preterm infants. No significant correlations were observed between FC (content or grades) and sex, gestational age, maternal age at pregnancy, NICU stay duration, breastfeeding cessation timing, or allergic diathesis in this cohort.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCA: corrected age; FC: fecal calprotectin; ICU: Neonatal Intensive Care Unit; NEC: necrotizing enterocolitis; PTI: Preterm infants.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author wishes to extend sincere gratitude to the participating infants and their parents, as well as the medical staff and workers in the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University, and Suzhou Maternal and Child Healthcare Hospital. In particular, Dr Lu Xiaoting, Dr Li Beiquan, and Dr Pan Qiuping.\u003c/p\u003e\n\u003cp\u003eAdditionally, we extend our gratitude to the Clinical Laboratory of Suzhou Hospital Affiliated to Nanjing Medical University for their contributions to specimen testing, and especially to Prof. Chen Yan for inspecting the fecal specimens. Our gratitude also goes to Guo Yi for the help with specimen collection. We also thank Dr Chen Yiyuan, M.M., a public health expert, for her key contributions. She handled quality control and conducted a review of the statistical data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by the Jiangsu Commission of Health [Jiangsu Health Commission Office Maternal and Child Health Document No. 19 (2021)].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eY. Cao, S. Jiang, J. Sun, M. Hei, L. Wang, H. Zhang, X. Ma, H. Wu, X. Li, H. Sun, W. Zhou, Y. Shi, Y. Wang, X. Gu, T. Yang, Y. Lu, L. Du, C. Chen, S. K. Lee and W. Zhou, JAMA network open. 2021, 4, e2118904\u003c/li\u003e\n \u003cli\u003eR. Bai, S. Jiang, J. Guo, S. Jiang, S. K. Lee, Z. Li and Y. Cao, Frontiers in pediatrics. 2021, 9, 760646\u003c/li\u003e\n \u003cli\u003eZhonghua fu chan ke za zhi. 2014, 49, 481\u003c/li\u003e\n \u003cli\u003eJ. Zeng, W. Yu, X. Gao, Y. Yu, Y. Zhou and X. Pan, PeerJ. 2025, 13, e19572\u003c/li\u003e\n \u003cli\u003eG. S. Bethell and N. J. Hall, Frontiers in pediatrics. 2023, 11, 1229850\u003c/li\u003e\n \u003cli\u003eX. Cai, H. L. Liebe, A. Golubkova, T. Leiva and C. J. Hunter, Current pediatric reviews. 2023, 19, 285\u003c/li\u003e\n \u003cli\u003eC. Bryce and M. Bucaj, American family physician. 2021, 104, 303\u003c/li\u003e\n \u003cli\u003eF. D\u0026apos;Amico, D. T. Rubin, P. G. Kotze, F. Magro, B. Siegmund, T. Kobayashi, P. A. Olivera, P. Bossuyt, L. Pouillon, E. Louis, E. Dom\u0026egrave;nech, S. Ghosh, S. Danese and L. Peyrin-Biroulet, United European gastroenterology journal. 2021, 9, 451\u003c/li\u003e\n \u003cli\u003eA. Mari, F. A. Baker, M. Mahamid, A. Yacoob, W. Sbeit and T. Khoury, Annals of gastroenterology. 2019, 32, 425\u003c/li\u003e\n \u003cli\u003eM. Velasco Rodr\u0026iacute;guez-Belv\u0026iacute;s, J. F. Viada Bris, C. Plata Fern\u0026aacute;ndez, A. Garc\u0026iacute;a-Salido, J. Asensio Ant\u0026oacute;n, G. Dom\u0026iacute;nguez Ortega and R. A. Mu\u0026ntilde;oz Codoceo, Paediatrics \u0026amp; child health. 2020, 25, 286\u003c/li\u003e\n \u003cli\u003eW. Xu, Y. Zhang, W. Zhao, J. Chen, K. Maas, N. Hussain, W. A. Henderson and X. Cong, Interdisciplinary nursing research. 2022, 1, 36\u003c/li\u003e\n \u003cli\u003eC. Anania, F. Mond\u0026igrave;, G. Brindisi, A. Spagnoli, D. De Canditiis, A. Gesmini, L. Marchetti, A. Fichera, M. G. Piccioni, A. M. Zicari and F. Olivero, Nutrients. 2025, 17,\u003c/li\u003e\n \u003cli\u003eZ. H. Zhang, W. Wang, X. H. Zhang, J. Pan and X. Chen, International archives of allergy and immunology. 2022, 183, 1189\u003c/li\u003e\n \u003cli\u003eL. Hao, S. Wang and W. Ji, Asia Pacific journal of clinical nutrition. 2025, 34, 298\u003c/li\u003e\n \u003cli\u003eB. Demirci, \u0026Ouml;. Yılmaz Topal, İ. Turgay Yağmur and E. Dibek Mısırlıoğlu, Postgraduate medicine. 2025, 137, 416\u003c/li\u003e\n \u003cli\u003eC. Roug\u0026eacute;, M. J. Butel, H. Piloquet, L. Ferraris, A. Legrand, M. Vodovar, M. Voyer, M. F. de la Cocheti\u0026egrave;re, D. Darmaun and J. C. Roz\u0026eacute;, PloS one. 2010, 5, e11083\u003c/li\u003e\n \u003cli\u003eR. Hannawayya, R. Puentes, N. Mirzadzare, K. Cirone, H. Amin, A. Soraisham, B. Alshaikh, S. Thomas and E. R. Cobo, Pediatric research. 2025, 98, 278\u003c/li\u003e\n \u003cli\u003eF. E. Mahjoub, N. Zahedi, B. Ashjai, M. T. Ashtiani, F. Farahmand, M. Monajemzadeh, L. Kashi and H. Iranikhah, The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi. 2013, 62, 288\u003c/li\u003e\n \u003cli\u003eA. Zhernakova, M. Yassour, L. J. Hall and M. C. Collado, Cell host \u0026amp; microbe. 2025, 33, 820\u003c/li\u003e\n \u003cli\u003eL. Roskes, A. Chamzas, B. Ma, A. E. Medina, M. Gopalakrishnan, R. M. Viscardi and S. Sundararajan, Pediatric research. 2025, 97, 2065\u003c/li\u003e\n \u003cli\u003eM. J. Kim, J. Y. Kim, M. Kang, M. H. Won, S. H. Hong and Y. Her, International journal of molecular sciences. 2020, 21,\u003c/li\u003e\n \u003cli\u003eJ. A. Larke, K. Kuhn-Riordon, D. H. Taft, K. Sohn, S. Iqbal, M. A. Underwood, D. A. Mills and C. M. Slupsky, Journal of pediatric gastroenterology and nutrition. 2022, 75, 535\u003c/li\u003e\n \u003cli\u003eG. Czaja-Bulsa, K. Bulsa, M. Łokieć and A. Drozd, Nutrients. 2024, 16,\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Intestinal inflammation, Premature, Constipation, Nutritional Support, Probiotics","lastPublishedDoi":"10.21203/rs.3.rs-8459794/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8459794/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo investigate the factors affecting fecal calprotectin in preterm infants at the corrected age of 10\u0026ndash;18 months.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis research employs a cross-sectional design. Infants with a gestational age of less than 37 weeks were recruited at a corrected age of 10 to 18 months (born between April 2023 and April 2024) from the Child Healthcare Department of Suzhou Hospital Affiliated to Nanjing Medical University between June 2024 to August 2024. The fecal calprotectin was measured and was classified into three grades: \u0026lt; 15\u0026micro;g/g, 15\u0026ndash;60\u0026micro;g/g/g, and \u0026gt;\u0026thinsp;60\u0026micro;g/g. Relevant information was collected.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eFecal calprotectin levels in preterm infants who received formula supplementation before 6 months of corrected age were lower than those in infants who received it after 6 months. In convalescent preterm infants with constipation, fecal calprotectin levels exhibit a mild elevation, typically below 60 \u0026micro;g/g. Probiotics demonstrate a more pronounced effect on improving fecal calprotectin grades rather than content.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eCompared with non-exclusively convalescing preterm infants within the corrected age of 6 months, those who were exclusively breastfed showed increased intestinal inflammation mediated by neutrophils. Constipation moderately elevates the fecal calprotectin levels. Probiotics may serve as a protective factor against a lower degree of neutrophil-mediated intestinal inflammation. During early gastrointestinal development, long-term, low-grade, and safe inflammatory stimulation may be a positive factor for intestinal barrier development.\u003c/p\u003e","manuscriptTitle":"The Landscape of Influential Factors on Fecal Calprotectin in Convalescing Preterm Infants (Corrected Age of 10-18 Months)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-09 06:38:51","doi":"10.21203/rs.3.rs-8459794/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f874bb94-58a3-4cd1-9812-fc1e9fb780cf","owner":[],"postedDate":"January 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-29T18:25:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-09 06:38:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8459794","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8459794","identity":"rs-8459794","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}