Combined diaphragm and lung ultrasound profiling in healthy full-term neonates: A study of early postnatal function

Combined diaphragm and lung ultrasound profiling in healthy full-term neonates: A study of early postnatal function | 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 Combined diaphragm and lung ultrasound profiling in healthy full-term neonates: A study of early postnatal function Ioannis Koutras, Ilias Chatziioannidis, Angeliki Kontou, Abraham Pouliakis, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8512179/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 Mar, 2026 Read the published version in European Journal of Pediatrics → Version 1 posted 10 You are reading this latest preprint version Abstract Diaphragmatic ultrasound (DU) and lung ultrasound (LU) are increasingly applied to evaluate neonatal respiratory muscle performance and lung aeration, respectively. This prospective, observational, single-center study assessed DU of both hemi-diaphragms and lung ultrasound (LU) in healthy full-term neonates on days of life (DOL) 1 and 3 to profile postnatal physiology and establish normative values. DU metrics included diaphragmatic excursion (DE), contraction velocity (DCV), inspiratory diaphragm (DTi) and expiratory diaphragm (DTe) thickness, diaphragmatic thickening fraction (DTF), and inter-hemidiaphragm DTF difference (ΔDTF). LU was performed using a six-zone, three-point scoring system (LUS). Perinatal-neonatal characteristics were recorded. Twenty newborns (10 male, 10 female, mean gestational age 39.0±1.2 weeks, mean birth weight 3334±343 g) were evaluated, with equal distribution between vaginal and cesarean deliveries. No significant differences were observed in DE, DCV, DTi, DTe, or DTF between DOL 1 and 3. Sex had no effect on DU parameters. Cesarean-born neonates demonstrated significantly lower DE and DTF on DOL 1, but values were comparable by DOL 3. LUS was similar between DOL 1 and DOL 3 [medians (Q1–Q3): 1 (0–1.3) and 1 (0–1), respectively, p=0.244], with no differences by delivery mode or sex. Conclusion: Diaphragmatic function is stable in healthy neonates without significant pulmonary involvement on LU during the first three postnatal days. Mode of delivery influences diaphragmatic performance on DOL 1 and should be considered in early assessments. Combined DU and LU provide complementary insights into neonatal respiratory adaptation and may serve as reference values for clinical practice and research. Diaphragm Lung Ultrasound Adaptation Neonate Figures Figure 1 What is Known Point-of-care diaphragmatic ultrasound (DU) and lung ultrasound (LU) are increasingly utilized as safe, bedside tools for assessing neonatal respiratory distress and supporting clinical decision-making. What is New: This is the first study to evaluate both DU and LU together in healthy term newborns during the first three days of life. Our data primarily provide diaphragm metrics (of both hemi-diaphragms) in healthy term neonates. We provide evidence of stable diaphragmatic function in the immediate postnatal period, transiently affected by the mode of delivery but unrelated to the newborn’s sex. Introduction Evaluation of neonatal respiratory status has traditionally relied on clinical assessment, chest radiography, and blood gas analysis. These methods, however, have limitations [1, 2] while, in the case of chest X-ray, fragile newborns are exposed to ionizing radiation [3]. In recent years, point-of-care diaphragmatic ultrasound (DU) and lung ultrasound (LU) have emerged as safe, bedside techniques that provide valuable insights into respiratory physiology and assist clinical decision-making. DU allows detailed assessment of the diaphragm—the principal respiratory muscle—by measuring excursion, thickness, and thickening fraction across the respiratory cycle [4, 5]. Not surprisingly, it has been mainly applied to predict successful extubation, in critically ill adults [4, 6], children [7, 8], and preterm neonates [9, 10]. By contrast, LU evaluates lung aeration through artifacts such as A-lines, B-lines, and lung sliding. This technique is increasingly used in diagnosing common neonatal respiratory disorders including respiratory distress syndrome, transient tachypnea, meconium aspiration syndrome, and pneumothorax as well as for assessing other neonatal conditions [11, 12]. For respiratory distress syndrome in particular, LU demonstrates higher sensitivity and specificity than chest radiography (up to 90% and 98%, respectively) [13]. In addition , lung ultrasound scores (LUS) have been validated for diagnosing and grading neonatal respiratory distress, with meta-analyses reporting pooled sensitivity of ~0.92, specificity of ~0.95 [14]. In addition, LUS has been used to predict failure of non-invasive respiratory support guiding surfactant therapy [15] or the need for invasive ventilation [16, 17], as well as assess risk of bronchopulmonary dysplasia development [18]. Nevertheless, despite the promising value of each modality, dual assessments remain uncommon in the neonatal period. Notably, one recent prospective study examined the ability of both ultrasound types to predict extubation success in extremely preterm infants [9]. In general, existing normative data on DU metrics in preterm and term neonates—particularly within the first 24–48 hours of life—remain limited in the current literature [19–23]. Other studies have described diaphragmatic function beyond the first postnatal week and at different time points during the 1 st month of life up to early infancy [24] childhood [25], leaving early neonatal adaptation period underexplored. We therefore aimed to evaluate diaphragmatic function and lung aeration concurrently using ultrasonography, thereby providing further insights into the normal postnatal respiratory physiology of the full-term newborn. Methods Study Design and Population This prospective, observational, single-center clinical study was conducted at our center in October and November 2025. We evaluated healthy full-term (≥ 37 weeks’ gestation) neonates roomed-in with their mothers in the obstetric department. Neonates who were clinically unstable after birth or had congenital anomalies were excluded. Written informed consent was obtained from both parents prior to enrollment. DU and LU were performed on the first and third days of life (DOL) by a single experienced investigator (I.K.). For imaging, neonates were temporarily transferred to the Neonatal Intensive Care Unit. Ultrasound examinations were performed bedside using a portable system (Vivid iq, GE Healthcare). Images and cine loops were acquired during quiet, rhythmic breathing, avoiding crying, yawning, sighing, or movement. Perinatal and neonatal characteristics were recorded, including gestational age, birth weight, sex, mode of delivery [vaginal (VD) vs. cesarean section (CS)], and Apgar scores at 1 and 5 minutes after birth. Ultrasound Measurement Techniques and Metrics A. Diaphragmatic ultrasound Diaphragmatic motion was assessed using a micro-convex probe (8 MHz) positioned subcostally at the right midclavicular line and the left anterior axillary line for the right and left hemidiaphragm, respectively. In B-mode, the diaphragm was visualized as a hyperechoic curved line separating the lung from the liver on the right side and from the spleen or stomach on the left side. In M-mode, diaphragmatic excursion (DE) was measured as the vertical displacement between the most caudal point of the diaphragm at end-inspiration and the most cranial point at end-expiration, with the mean value of three respiratory cycles recorded [4]. Inspiratory time (Ti) was defined as the temporal interval between the caudal and cranial peaks of diaphragmatic motion in M-mode (Fig 1a). Diaphragm contraction velocity (DCV) was calculated as DE/Ti [21]. Diaphragm thickness was assessed using a high-frequency linear “hockey stick” probe linear probe (8–18 MHz) in the zone of apposition (ZOA), between the 8th and 10th intercostal spaces, along the anterior to midaxillary lines bilaterally. In B-mode, the diaphragm was visualized as a hypoechoic band bordered by two echogenic lines: the superficial pleural membrane and the deeper peritoneal membrane. In M-mode, inspiratory diaphragm thickness (DTi) was defined as the maximal perpendicular distance between the pleural and peritoneal lines, and expiratory diaphragm thickness (DTe) as the minimal distance (Fig 1b). Measurements were averaged over at least three respiratory cycles. The diaphragmatic thickening fraction (DTF) was calculated using the formula: DTF= (DTi-DTe)/DTe x100% [9]. The difference in DTF (ΔDTF) between the two hemidiaphragms was also calculated in the present study. B. Lung Ultrasound LU was performed using the same linear probe (8–18 MHz). Three chest zones were examined on each hemithorax (upper anterior, lower anterior, and lateral), following the protocol described by Brat et al. [15]. Each lung field was interrogated intercostally with the probe positioned perpendicular to the ribs and costal cartilages, and the imaging depth set at 3 cm. Ultrasonographic findings were classified according to the Brat scoring system. Briefly: A-line pattern (score 0), ≥3 non-coalescent B-lines (score 1), coalescent B-lines with or without subpleural consolidation (score 2), and extensive consolidation (score 3). The cumulative score from the six lung zones constituted the total LUS score (range: 0–18) [15]. Statistical analysis The statistical analysis was performed using R version 4.5.1. Descriptive characteristics for quantitative data were expressed as median and Quartile 1 (Q1) to Quartile 3 (Q3), range, or mean±standard deviation, depending on normality. Diaphragmatic function metrics were compared by measurement site (right vs. left), DOL, gender, and delivery method at DOL 1 and 3. Statistical tests included independent samples t-test or Mann–Whitney U test (the latter when normality was not confirmed via the Shapiro–Wilk test), and for dependent data (DOL 1 vs. DOL 3), paired t-test or Wilcoxon signed-rank test. Correlations between arithmetic data were evaluated using Spearman’s correlation coefficient (rs). The significance level (p-value) was set at 0.05, and two-sided tests were applied when appropriate. Results Twenty healthy, appropriate for gestational age full-term neonates (10 male/10 female), infants were evaluated (mean GA: 39.0±1.2 weeks; mean BW: 3335±334 g). Half were born via VD, half via CS. No studied neonate required resuscitation at birth and only routine care was applied. Apgar scores were 8±0.3 and 9±0 at 1 and 5 min after delivery, respectively. Diaphragmatic function metrics on DOL 1 and 3 are presented in Table 1. DE, DCV, DTi, DTe, and DTF remained stable. Sex had no effect on diaphragmatic function at both time points of the study (Table S1). However, cesarean section-born neonates showed significantly lower DE (both sides) and DTF (left side) on DOL 1 (Table 2). No significant difference was observed in LUS between DOL 1 and DOL 3 [medians (Q1–Q3): 1 (0–1.3) and 1 (0–1), respectively, p=0.244]. As shown in Table S2, normal lung patterns predominated across all regions and time points, with only minor increases in mild findings in some lower and middle fields. Additional analysis showed comparable LUS between neonates born via VD and CS on DOL 1 [medians (Q1–Q3): 1 (0.25–1) and 1 (0.25–1.75), respectively, p=0.657] and on DOL 3 [1 (0–1) for both groups; p=0.617]. No differences were also observed between female and male infants at either time point (DOL 1: females vs. males, 1 (0.25–1) vs. 1 (0.25–2), respectively, p=0.615, DOL 3: 1 (0–1) for both, p=0.615). On DOL 1, DE showed a significant moderate positive correlation with both DTF (r s =0.58, p=0.008) and DTe - DTi (r s =0.56, p=0.01) for the left hemi-diaphragm, whereas no significant correlations were observed on the right side. On DOL 3, DE remained significantly correlated with DTF on the left (r s =0.49, p=0.027), while no other associations reached statistical significance (Table S3). Discussion This prospective, observational, single-center study aimed to evaluate diaphragmatic function and lung aeration using ultrasonography on DOL 1 and 3. We found that diaphragmatic function, as indicated by specific metrics (DE, DCV, DTi, DTe, and DTF), remains stable in healthy neonates without significant pulmonary involvement documented by LU. Sex had no effect on diaphragmatic function. However, cesarean-born neonates showed significantly lower DE and DTF on DOL 1 only, despite both vaginally and cesarean-born neonates exhibiting similarly low LUS at both time points. Diaphragmatic parameters offer valuable mechanistic insight into neonatal respiration, with DE reflecting overall movement and DTF indicating contractile function. Elevated DE and DTF values may indicate either improved diaphragmatic function or increased respiratory effort in response to a higher work of breathing [26]. Nevertheless, evidence on normative neonatal values remains sparse. Few studies have reported DE values in term neonates, and our findings appear to be more consistent with some of these [23]. One such study by Laing et al. (1987) was the first to report DE values (4.6±0.2 mm) for the right hemi-diaphragm in healthy newborn infants [27]. Similarly, Yeung et al. reported comparable DE values in term or near term infants (4.4±1.6 mm), which were significantly lower than those observed in preterm infants with BPD (6.0±1.7 mm) [28]. Another cross-sectional study by Martins et al. evaluated ultrasound measures of peripheral muscles and diaphragm function in 120 stable preterm and full-term infants. Regarding the diaphragm, significant differences in both thickness and excursion were observed between term infants (DE 4.6±3 mm) and very preterm infants. Notably, this is one of the few investigations in the neonatal age to report on DCV, a dynamic ultrasound metric that reflects the speed of diaphragmatic contraction [21]. In adults, DCV has been studied as a predictor of successful weaning from mechanical ventilation, though results have been conflicting [29, 30]. In neonates, reduced DCV has been reported in pathological conditions such as patent ductus arteriosus [31]. Findings from the present study suggest that DCV appears to be a robust and consistent parameter in the early neonatal period, with minimal influence from perinatal factors such as mode of delivery or sex. Furthermore, our values are comparable to those reported by Martins et al. for term infants (1.36±0.39 cm/s) [21], thereby supporting the notion that diaphragmatic ultrasound may serve as a reliable tool for the assessment of respiratory muscle function in neonatal care. Understanding normal diaphragm thickness in healthy term neonates is essential for interpreting respiratory muscle development and function in early life. Rehan et al. examined 16 healthy term infants within two days of birth (one on day 17). Right hemi-diaphragm thickness was measured at inspiration and expiration during quiet sleep in prone and supine positions, with simultaneous cardiorespiratory monitoring. Thickness was significantly greater in the prone position. Reported DTi (2.26±0.3 mm) and DTe (1.97±0.3 mm) in supine closely resembled our findings [19]. Alonso-Ojembarrena et al. measured 33 preterm and 33 term newborns within 48 hours, reporting lower DTi and DTe in preterms but similar diaphragmatic shortening fractions (a marker of diaphragmatic shortening during inspiration, related to DTF) [20]. Buonsenso et al. defined normal values in 22 healthy infants (7 days–6 months) [24], while another study in 137 children (0–8 years) showed higher DTi in infants (<1 year ≈ 2.07 mm) and DTF ≈ 25% [25]. Recently, Carvalho et al. examined 100 term neonates (24–28 hours), providing reference values for DTi, DTe, DTF and DE [23]. Diaphragm thickness in our study aligned with literature and was unaffected by sex or delivery mode whereas thickening fraction remained stable. Right-sided ultrasound is generally preferred across all ages as the liver provides a reliable acoustic window, whereas imaging the left hemi-diaphragm is more challenging due to the smaller spleen window and potential gastric air interference [4, 32]. Unlike most previous studies assessing only the right neonatal hemi-diaphragm, we evaluated both sides. To our knowledge, only one prior neonatal study adopted a similar approach, though it compared preterm and term infants without analyzing side-to-side variation within groups [20]. In our cohort at DOL 1, right-sided DT at inspiration and expiration were slightly higher than left-sided values, though not statistically significant. These small lateral differences likely reflect normal anatomical variation. For both hemi-diaphragms, no significant changes in DT or DTF occurred between DOL 1 and DOL 3, indicating stable diaphragmatic structure and function in healthy term infants during the first 72 hours. Additionally, we calculated the side-to-side diaphragmatic thickening fraction difference (ΔDTF, %) as an objective, reproducible measure of inter-hemi diaphragmatic performance [33]. We observed a minimal mean ΔDTF (suggesting a trend for symmetric diaphragmatic function) but marked interindividual variability. Duyndam et al evaluating the right hemi-diaphragm in healthy children, reported DTF standard deviations from 12.5% (0-6 months) to 10.9% (5-8 years) [25]. In healthy men and women, similar DTF values were observed during quiet and deep breathing, although notable side-to-side differences were present [34]. Importantly, even small absolute differences in thickness (fractions of a millimeter) may translate into appreciable percentage differences. To date, no study has validated a cutoff value for neonatal ΔDTF. In the present study, moderate correlations between DE and DTF were also observed on the left hemi-diaphragm at both DOL 1 and 3, suggesting a functional link between left-sided thickening and diaphragmatic movement. Correlations on the right side were weaker and non-significant, possibly due to greater interindividual variability or technical challenges. As reported by Bahdat et al. in ventilated preterm infants, the liver’s supporting effect during inspiration may mask subtle right-sided changes. These anatomical factors likely account for side-to-side differences and highlight the importance of assessing the left hemidiaphragm, which may provide more reliable measurements [35]. Moreover, the absolute thickness change (DTe–DTi) showed a moderate correlation with DE only on the left side at DOL 1. These findings suggest that DTF may be a more reliable marker of diaphragmatic function in early neonatal life, which may explain why absolute thickness change is rarely reported as a separate measurement [8]. Further research is warranted to clarify the clinical relevance and potential applications of this diaphragmatic parameter. Based on previous studies reporting thinner diaphragm in healthy women than in men [36, 37], we also investigated potential sex-related differences in diaphragmatic function. Although this hypothesis could not be supported in our study, such differences may still emerge under specific pathological conditions. A large analysis in infants with bronchopulmonary dysplasia reported thinner diaphragms in male compared to females [38]. In contrast, we observed that mode of delivery influences diaphragmatic activity. Neonates born vaginally had greater DE and left-sided DTF immediately after birth. By DOL 3, these differences were no longer significant, reflecting early postnatal respiratory adaptation within 48–72 hours. These findings likely reflect the mechanical and physiological stresses of vaginal delivery and the absence of labor-associated respiratory stimulation in cesarean sections. Although literature on diaphragmatic function by delivery mode is limited, labor and vaginal birth facilitate lung fluid clearance and stimulate spontaneous respiratory efforts [39]. Consequently, reference values for DE and DTF at DOL 1 should consider delivery mode, even though these differences normalize rapidly. In this context, this study is the first to integrate both DU and LU in healthy term newborns. In critically ill adults, diaphragm dysfunction has been linked to loss of lung aeration and difficult ventilator weaning [40]. Most prior research focused on one modality or preterm/ill infants. A recent prospective study in extremely preterm ventilated infants demonstrated that LU was superior to diaphragmatic indices in predicting extubation success [41]. In our cohort, as expected, we observed low LUS values, reflecting normal lung patterns across all regions and time points, with only minor increases in mild findings in right lower and left lateral fields. These results align with well-aerated lungs after effective postnatal adaptation [42]. Simultaneously, high DTF (~30%) and DE (~4–5 mm) values indicate strong respiratory muscle function in normal lungs. Interestingly, observed DTF (~30–34%) exceeded the 20% threshold often used in adult and pediatric studies to indicate dysfunction [35]. suggesting healthy term newborns exhibit robust diaphragmatic contractility. Beyond the combined use of DU and LU, our study has several strengths. Inclusion of neonates on both DOL 1 and 3 provides rare early-life data, expanding limited evidence on diaphragmatic function in this age group. Bilateral assessments allowed detection of asymmetry potentially missed with right-sided measurements alone. Limitations include the small sample size and follow-up restricted to two early time points. Lastly, all DU measurements were performed by a single investigator. While this minimizes inter-observer variability and ensures consistency, it prevents assessment of reproducibility across operators and may limit generalizability. Recent neonatal studies have shown excellent intra-observer and acceptable inter-observer reproducibility for diaphragmatic shortening fraction in both term and preterm infants [20]. Another study in 2024 reported good intrarater and moderate interrater reliability for the diaphragmatic thickness and mobility , while DTF interrater reliability was poor [22] . Future studies should enroll larger cohorts with longer follow-up to track diaphragmatic maturation beyond the early neonatal period, ideally through multi-center collaboration. Such investigations should also focus on at-risk neonatal populations to better delineate early-life adaptations and potential long-term consequences. As the diaphragm is a single functional unit but current measurements sample limited sites, standardizing methodology is essential. Future work should compare imaging modalities, assess multiple regions (ZOA and crural), explore novel metrics such as displacement curve area, combined length–thickness measures, surface variability, and contraction velocity, and integrate automated image analysis to enable broader clinical implementation. Conclusion Combined diaphragm-lung assessment using ultrasound provides valuable insights into early respiratory adaptation and may help establish reference values. In healthy full-term neonates, our study using this dual approach demonstrated stable, robust diaphragmatic function during the first three days of life, with no significant sex-related differences and only a transient effect of delivery mode, with vaginal birth associated with greater diaphragmatic activity compared to cesarean section. Abbreviations Cesarian section (CS) Day of life (DOL) Diaphragmatic excursion (DE) Diaphragmatic thickening fraction (DTF) Diaphragmatic ultrasound (DU) Diaphragm contraction velocity (DCV) Difference in DTF (ΔDTF) Expiratory diaphragm thickness (DTe) Inspiratory diaphragm thickness (DTi) Inspiratory time (Ti) Lung ultrasound (LU) Lung Ultrasound Score (LUS) Vaginal delivery (VD) Zone of apposition (ZOA) Declarations Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Competing Interests The authors have no relevant financial or non-financial interests to disclose. Author Contributions All authors contributed to the study conception and design. Material preparation and data collection were performed by Ioannis Koutras, Ilias Chatziioannidis, and Angeliki Kontou, while data analysis was conducted by Abraham Pouliakis and Kosmas Sarafidis. The first draft of the manuscript was written by Kosmas Sarafidis, Ioannis Koutras, and Ilias Chatziioannidis, and all authors provided comments on previous versions of the manuscript. All authors read and approved the final manuscript. Ethics approval This observational study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of our Institution (25-09-25/11th session, item 17.). Consent to participate Written informed consent was obtained from the parents of the studies neonates. Acknowledgments We thank the parents of the enrolled infants for their contributions to this study, as well as the nursing staff at our center for their assistance during the ultrasound examinations. References Hiles M, Culpan A-M, Watts C et al (2017) Neonatal respiratory distress syndrome: Chest X-ray or lung ultrasound? A systematic review. 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Eur J Pediatr 180:899–908. https://doi.org/10.1007/s00431-020-03805-2 Carrillo-Esper R, Pérez-Calatayud ÁA, Arch-Tirado E et al (2016) Standardization of Sonographic Diaphragm Thickness Evaluations in Healthy Volunteers. Respir Care 61:920–924. https://doi.org/10.4187/respcare.03999 Boussuges A, Rives S, Finance J et al (2021) Ultrasound Assessment of Diaphragm Thickness and Thickening: Reference Values and Limits of Normality When in a Seated Position. Front Med (Lausanne) 8:742703. https://doi.org/10.3389/fmed.2021.742703 Yeung T, Ibrahim J, Mohamed A (2024) Sex-Based Differences in the Sonographic Characterization of Diaphragm Thickness in Preterm Infants With Bronchopulmonary Dysplasia at Term Corrected Age: A Secondary Analysis of a Prospective Study. J Ultrasound Med 43:1053–1061. https://doi.org/10.1002/jum.16434 Hillman NH, Kallapur SG, Jobe AH (2012) Physiology of transition from intrauterine to extrauterine life. Clin Perinatol 39:769–783. https://doi.org/10.1016/j.clp.2012.09.009 Dres M, Rozenberg E, Morawiec E et al (2021) Diaphragm dysfunction, lung aeration loss and weaning-induced pulmonary oedema in difficult-to-wean patients. Ann Intensive Care 11:99. https://doi.org/10.1186/s13613-021-00886-6 Mohsen N, Nasef N, Ghanem M et al (2023) Accuracy of lung and diaphragm ultrasound in predicting successful extubation in extremely preterm infants: A prospective observational study. Pediatr Pulmonol 58:530–539. https://doi.org/10.1002/ppul.26223 Blank DA, Kamlin COF, Rogerson SR et al (2018) Lung ultrasound immediately after birth to describe normal neonatal transition: an observational study. Arch Dis Child Fetal Neonatal Ed 103:F157–F162. https://doi.org/10.1136/archdischild-2017-312818 Tables Table 1. Diaphragmatic function metrics on Days of Life (DOL) 1 and 3. DOL 1 DOL 3 DOL 1 vs. DOL 3 Right hemi-diaphragm Left hemi-diaphragm P1 Right vs. Left hemi-diaphragm Right hemi-diaphragm Left hemi-diaphragm P2 Right vs. Left hemi-diaphragm P3 Right hemi-diaphragm P4 Left hemi-diaphragm DE (mm) 4.07 [3.38, 4.93] 4.70 [3.47, 5.26] 0.130* 4.21 [3.58, 5.04] 4.61 [3.54, 5.33] 0.546* 0.550* 0.571* DCV (mm/sec) 9.89 [8.08, 13.00] 11.51 [9.31, 13.19] 0.090* 10.18 [9.39, 15.26] 12.44 [8.83, 16.69] 0.165* 0.784* 0.648* DTi (mm) 2.34±0.46 2.12±0.56 0.124 2.35 ±0.47 2.12 ±0.63 0.038 0.921 0.958 DTe (mm) 1.80 ±0.34 1.67 ±0.49 0.233 1.80 ±0.40 1.59 ±0.49 0.062 0.974 0.609 DTF (%) 30.3±13.5 29.0±11.1 0.710 31.7 ±13.5 33.8 ±11.8 0.518 0.709 0.218 ΔDTF (%) 1.4±16.1 NA -2.0±13.9 NA 0.506 All comparisons between paired time points were performed using paired t‑tests, except where data violated normality assumptions—in those cases (marked with *), the Wilcoxon signed‑rank test was applied and results are presented as median [Q1, Q3]. Table 2. Diaphragmatic function metrics on Days of Life (DOL) 1 and 3 according to mode of delivery. Time point Side Metrics Vaginal Delivery (n=10) Cesarean Section (n=10) P-value * DOL 1 Right hemi-diaphragm DE (mm) 4.55 [3.94, 5.08] 3.54 [3.09, 4.14] 0.041 DCV (mm/sec) 9.89 [9.14, 11.11] 9.74 [7.45, 13.23] 0.650 DTi (mm) 2.49±0.57 2.18±0.27 0.138 DTe (mm) 1.90±0.38 1.70±0.27 0.183 DTF (%) 30.96±12.98 29.69±14.67 0.840 Left hemi-diaphragm DE (mm) 5.31 [4.79, 6.46] 3.62 [2.93, 4.48] 0.005 DCV (mm/sec) 11.92 [10.69, 17.71] 9.57 [7.83, 12.57] DTi (mm) 2.04±0.46 2.21±0.66 0.545 DTe (mm) 1.50±0.31 1.83±0.59 0.241 DTF (%) 36.42±10.19 21.50±5.89 0.001 ΔDTF (%) -5.467±15.76 8.19±14.01 0.056 DOL 3 Right hemi-diaphragm DE (mm) 4.38 [4.02, 5.27] 3.65 [3.33, 4.35] 0.140 DCV (mm/sec) 12.08 [9.85, 21.49] 9.87 [8.92, 11.44] 0.290 DTi (mm) 2.37±0.58 2.33±0.35 0.855 DTe (mm) 1.78±0.50 1.81±0.29 0.884 DTF (%) 33.67±12.03 29.77±15.24 0.534 Left hemi-diaphragm DE (mm) 5.01 [3.91, 5.78] 3.95 [3.20, 4.64] 0.395 DCV (mm/sec) 12.44 [9.62, 15.34] 12.73 [9.02, 17.82] 0.082 DTI (mm) 2.36±0.75 1.87±0.37 0.064 DTe (mm) 1.77±0.56 1.41±0.34 0.064 DTF (%) 33.34±12.16 34.18±12.00 0.877 ΔDTF (%) 0.33±15.31 -4.42±12.63 0.460 An independent samples t-test or Mann–Whitney U test was used depending on normality . Results are reported as mean ± standard deviation for normally distributed data, or as median and [Q1, Q3] for non-normally distributed data. Additional Declarations No competing interests reported. Supplementary Files SUPPLEMENTARYTABLES13.docx Cite Share Download PDF Status: Published Journal Publication published 21 Mar, 2026 Read the published version in European Journal of Pediatrics → Version 1 posted Editorial decision: Revision requested 07 Feb, 2026 Reviews received at journal 05 Feb, 2026 Reviews received at journal 02 Feb, 2026 Reviewers agreed at journal 25 Jan, 2026 Reviewers agreed at journal 25 Jan, 2026 Reviewers agreed at journal 23 Jan, 2026 Reviewers invited by journal 23 Jan, 2026 Editor assigned by journal 22 Jan, 2026 Submission checks completed at journal 22 Jan, 2026 First submitted to journal 04 Jan, 2026 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. 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Ippokrateion General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ilias","middleName":"","lastName":"Chatziioannidis","suffix":""},{"id":580128820,"identity":"886ab725-1632-4402-a5e4-b83ad8923574","order_by":2,"name":"Angeliki Kontou","email":"","orcid":"","institution":"Aristotle University of Thessaloniki, Ippokrateion General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Angeliki","middleName":"","lastName":"Kontou","suffix":""},{"id":580128821,"identity":"51dc5e8c-8875-489f-a8e4-9ee004c36e00","order_by":3,"name":"Abraham Pouliakis","email":"","orcid":"","institution":"National and Kapodistrian University of Athens \"ATTIKON\" University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Abraham","middleName":"","lastName":"Pouliakis","suffix":""},{"id":580128823,"identity":"8fd84d52-a9d0-4149-8d8a-585fbd3beb2a","order_by":4,"name":"Kosmas Sarafidis","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtklEQVRIiWNgGAWjYBACCQglJwck2EjSYmzMwMBMopbEBqK1SLa3P/xcUWOQ3j8j/9gDhl/3CGuR5jljLHnmmEHujBvJ7AaMfcWEtchJ5DBINrD9yW24kcwmwdiTQIyW9Mc/G/4ZpMsTrUVaIsFMsrHNIMEApIXhBxFaJHvOmFk29hkYbjzz2EwisYEILRLH2x/fbPhmIC93PPGZxIc/RGhBBYltpOpgYPhDupZRMApGwSgY/gAAea42gUjCaMsAAAAASUVORK5CYII=","orcid":"","institution":"Aristotle University of Thessaloniki, Ippokrateion General Hospital","correspondingAuthor":true,"prefix":"","firstName":"Kosmas","middleName":"","lastName":"Sarafidis","suffix":""}],"badges":[],"createdAt":"2026-01-04 10:08:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8512179/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8512179/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00431-026-06850-5","type":"published","date":"2026-03-21T15:59:21+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":101364455,"identity":"fffc831d-8731-4245-9db3-f881ec230796","added_by":"auto","created_at":"2026-01-29 00:50:08","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":451107,"visible":true,"origin":"","legend":"\u003cp\u003ea) Measurement of diaphragmatic excursion (DE) and inspiratory time (Ti): BC=DE, AC=Ti).\u003c/p\u003e\n\u003cp\u003eb) Measurement of diaphragm thickness: AB=DTe (end-expiration thickness), CD=DTi (end-inspiration thickness).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8512179/v1/bbc4b4dfdaf2cafebc9e9bc1.jpeg"},{"id":105223416,"identity":"71df62fa-aa94-4370-b773-d7d7644d265e","added_by":"auto","created_at":"2026-03-23 16:06:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1355320,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8512179/v1/dc2010a0-4f08-47aa-a136-b4706b394dc8.pdf"},{"id":101364453,"identity":"11857c5f-fd99-4031-bce1-4d5203d3a64b","added_by":"auto","created_at":"2026-01-29 00:50:07","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":21868,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPLEMENTARYTABLES13.docx","url":"https://assets-eu.researchsquare.com/files/rs-8512179/v1/cc01a6d8358afa10737c784d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Combined diaphragm and lung ultrasound profiling in healthy full-term neonates: A study of early postnatal function","fulltext":[{"header":"What is Known","content":"\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e Point-of-care diaphragmatic ultrasound (DU) and lung ultrasound (LU) are increasingly utilized as safe, bedside tools for assessing neonatal respiratory distress and supporting clinical decision-making.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\n\u003ch3\u003eWhat is New:\u003c/h3\u003e\n\u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eThis is the first study to evaluate both DU and LU together in healthy term newborns during the first three days of life.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eOur data primarily provide diaphragm metrics (of both hemi-diaphragms) in healthy term neonates.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eWe provide evidence of stable diaphragmatic function in the immediate postnatal period, transiently affected by the mode of delivery but unrelated to the newborn\u0026rsquo;s sex.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"Introduction","content":"\u003cp\u003eEvaluation of neonatal respiratory status has traditionally relied on clinical assessment, chest radiography, and blood gas analysis. These methods, however, have limitations [1, 2] while, in the case of chest X-ray, fragile newborns are exposed to ionizing radiation [3].\u003c/p\u003e\n\u003cp\u003eIn recent years, point-of-care diaphragmatic ultrasound (DU) and lung ultrasound (LU) have emerged as safe, bedside techniques that provide valuable insights into respiratory physiology and assist clinical decision-making. DU allows detailed assessment of the diaphragm\u0026mdash;the principal respiratory muscle\u0026mdash;by measuring excursion, thickness, and thickening fraction across the respiratory cycle [4, 5].\u0026nbsp; \u0026nbsp;Not surprisingly, it has been mainly applied to predict successful extubation, in critically ill adults\u0026nbsp;[4, 6], children\u0026nbsp;[7, 8], and preterm neonates\u0026nbsp;[9, 10].\u003c/p\u003e\n\u003cp\u003eBy contrast, LU evaluates lung aeration through artifacts such as A-lines, B-lines, and lung sliding. This technique is increasingly used in diagnosing common neonatal respiratory disorders including respiratory distress syndrome, transient tachypnea, meconium aspiration syndrome, and pneumothorax as well as for assessing other neonatal conditions [11, 12]. For respiratory distress syndrome in particular, LU demonstrates higher sensitivity and specificity than chest radiography (up to 90% and 98%, respectively) [13]. In addition\u003cstrong\u003e,\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003elung ultrasound scores (LUS)\u003c/strong\u003e have been validated for diagnosing and grading neonatal respiratory distress, with meta-analyses reporting pooled sensitivity of ~0.92, specificity of ~0.95\u0026nbsp;[14]. In addition, LUS has been used to predict failure of non-invasive respiratory support guiding surfactant therapy\u0026nbsp;[15]\u0026nbsp;or the need for invasive ventilation\u0026nbsp;[16, 17], as well as assess risk of bronchopulmonary dysplasia development\u0026nbsp;[18].\u003c/p\u003e\n\u003cp\u003eNevertheless, despite the promising value of each modality, dual assessments remain uncommon in the neonatal period. Notably, one recent prospective study examined the ability of both ultrasound types to predict extubation success in extremely preterm infants [9]. In general, existing normative data on DU metrics in preterm and term neonates\u0026mdash;particularly within the first 24\u0026ndash;48 hours of life\u0026mdash;remain limited in the current literature\u0026nbsp;[19\u0026ndash;23]. Other studies have described diaphragmatic function beyond the first postnatal week and at different time points during the 1\u003csup\u003est\u003c/sup\u003e month of life up to early infancy\u0026nbsp;[24]\u0026nbsp; childhood\u0026nbsp;[25], leaving early neonatal adaptation period underexplored.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe therefore aimed to evaluate diaphragmatic function and lung aeration concurrently using ultrasonography, thereby providing further insights into the normal postnatal respiratory physiology of the full-term newborn.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy Design and Population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis prospective, observational, single-center clinical study was conducted at our center in October and November 2025. We evaluated healthy full-term (\u0026ge; 37 weeks\u0026rsquo; gestation) neonates roomed-in with their mothers in the obstetric department. Neonates who were clinically unstable after birth or had congenital anomalies were excluded. Written informed consent was obtained from both parents prior to enrollment. DU and LU were performed on the first and third days of life (DOL) by a single experienced investigator (I.K.). For imaging, neonates were temporarily transferred to the Neonatal Intensive Care Unit. Ultrasound examinations were performed bedside using a portable system (Vivid iq, GE Healthcare). Images and cine loops were acquired during quiet, rhythmic breathing, avoiding crying, yawning, sighing, or movement. Perinatal and neonatal characteristics were recorded, including gestational age, birth weight, sex, mode of delivery [vaginal (VD) vs. cesarean section (CS)], and Apgar scores at 1 and 5 minutes after birth.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUltrasound Measurement Techniques and Metrics\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA.\u0026nbsp; \u0026nbsp;Diaphragmatic ultrasound\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDiaphragmatic motion was assessed using a micro-convex probe (8 MHz) positioned subcostally at the right midclavicular line and the left anterior axillary line for the right and left hemidiaphragm, respectively. In B-mode, the diaphragm was visualized as a hyperechoic curved line separating the lung from the liver on the right side and from the spleen or stomach on the left side. In M-mode, diaphragmatic excursion (DE) was measured as the vertical displacement between the most caudal point of the diaphragm at end-inspiration and the most cranial point at end-expiration, with the mean value of three respiratory cycles recorded [4]. Inspiratory time (Ti) was defined as the temporal interval between the caudal and cranial peaks of diaphragmatic motion in M-mode (Fig 1a). \u0026nbsp;Diaphragm contraction velocity (DCV) was calculated as DE/Ti [21].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDiaphragm thickness was assessed using a high-frequency linear \u0026ldquo;hockey stick\u0026rdquo; probe linear probe (8\u0026ndash;18 MHz) in the zone of apposition (ZOA), between the 8th and 10th intercostal spaces, along the anterior to midaxillary lines bilaterally. In B-mode, the diaphragm was visualized as a hypoechoic band bordered by two echogenic lines: the superficial pleural membrane and the deeper peritoneal membrane. In M-mode, inspiratory diaphragm thickness (DTi) was defined as the maximal perpendicular distance between the pleural and peritoneal lines, and expiratory diaphragm thickness (DTe) as the minimal distance (Fig 1b). Measurements were averaged over at least three respiratory cycles. The diaphragmatic thickening fraction (DTF) was calculated using the formula: DTF= (DTi-DTe)/DTe x100% [9]. The difference in DTF (\u0026Delta;DTF) between the two hemidiaphragms was also calculated in the present study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB.\u0026nbsp; \u0026nbsp;\u0026nbsp;Lung Ultrasound\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLU was performed using the same linear probe\u0026nbsp;(8\u0026ndash;18 MHz). Three chest zones were examined on each hemithorax (upper anterior, lower anterior, and lateral), following the protocol described by Brat et al. [15]. Each lung field was interrogated intercostally with the probe positioned perpendicular to the ribs and costal cartilages, and the imaging depth set at 3 cm. Ultrasonographic findings were classified according to the Brat scoring system. Briefly: A-line pattern (score 0), \u0026ge;3 non-coalescent B-lines (score 1), coalescent B-lines with or without subpleural consolidation (score 2), and extensive consolidation (score 3). The cumulative score from the six lung zones constituted the total LUS score (range: 0\u0026ndash;18) [15].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe statistical analysis was performed using R version 4.5.1. Descriptive characteristics for quantitative data were expressed as median and Quartile 1 (Q1) to Quartile 3 (Q3), range, or mean\u0026plusmn;standard deviation, depending on normality. Diaphragmatic function metrics were compared by measurement site (right vs. left), DOL, gender, and delivery method at DOL 1 and 3. Statistical tests included independent samples t-test or Mann\u0026ndash;Whitney U test (the latter when normality was not confirmed via the Shapiro\u0026ndash;Wilk test), and for dependent data (DOL 1 vs. DOL 3), paired t-test or Wilcoxon signed-rank test. Correlations between arithmetic data were evaluated using Spearman\u0026rsquo;s correlation coefficient (rs). The significance level (p-value) was set at 0.05, and two-sided tests were applied when appropriate.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eTwenty healthy, appropriate for gestational age full-term neonates (10 male/10 female), infants were evaluated (mean GA: 39.0\u0026plusmn;1.2 weeks; mean BW: 3335\u0026plusmn;334 g). Half were born via VD, half via CS. No studied neonate required resuscitation at birth and only routine care was applied. Apgar scores were 8\u0026plusmn;0.3 and 9\u0026plusmn;0 at 1 and 5 min after delivery, respectively.\u003c/p\u003e\n\u003cp\u003eDiaphragmatic function metrics on DOL 1 and 3 are presented in Table 1. DE, DCV, DTi, DTe, and DTF remained stable. Sex had no effect on diaphragmatic function at both time points of the study (Table S1). However, cesarean section-born neonates showed significantly lower DE (both sides) and DTF (left side) on DOL 1 (Table 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNo significant difference was observed in LUS between DOL 1 and DOL 3 [medians (Q1\u0026ndash;Q3): 1 (0\u0026ndash;1.3) and 1 (0\u0026ndash;1), respectively, p=0.244]. As shown in Table S2, normal lung patterns predominated across all regions and time points, with only minor increases in mild findings in some lower and middle fields. Additional analysis showed comparable LUS between neonates born via VD and CS on DOL 1 [medians (Q1\u0026ndash;Q3): 1 (0.25\u0026ndash;1) and 1 (0.25\u0026ndash;1.75), respectively, p=0.657] and on DOL 3 [1 (0\u0026ndash;1) for both groups; p=0.617]. No differences were also observed between female and male infants at either time point (DOL 1: females vs. males, 1 (0.25\u0026ndash;1) vs. 1 (0.25\u0026ndash;2), respectively, p=0.615, DOL 3: 1 (0\u0026ndash;1) for both, p=0.615).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOn DOL 1, DE showed a significant moderate positive correlation with both DTF (r\u003csub\u003es\u003c/sub\u003e=0.58, p=0.008) and DTe - DTi (r\u003csub\u003es\u003c/sub\u003e=0.56, p=0.01) for the left hemi-diaphragm, whereas no significant correlations were observed on the right side. On DOL 3, DE remained significantly correlated with DTF on the left (r\u003csub\u003es\u003c/sub\u003e=0.49, p=0.027), while no other associations reached statistical significance (Table S3).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis prospective, observational, single-center study aimed to evaluate diaphragmatic function and lung aeration using ultrasonography on DOL 1 and 3. We found that diaphragmatic function, as indicated by specific metrics (DE, DCV, DTi, DTe, and DTF), remains stable in healthy neonates without significant pulmonary involvement documented by LU. Sex had no effect on diaphragmatic function. However, cesarean-born neonates showed significantly lower DE and DTF on DOL 1 only, despite both vaginally and cesarean-born neonates exhibiting similarly low LUS at both time points.\u003c/p\u003e\n\u003cp\u003eDiaphragmatic parameters offer valuable mechanistic insight into neonatal respiration, with DE reflecting overall movement and DTF indicating contractile function. Elevated DE and DTF values may indicate either improved diaphragmatic function or increased respiratory effort in response to a higher work of breathing [26]. Nevertheless, evidence on normative neonatal values remains sparse.\u003c/p\u003e\n\u003cp\u003eFew studies have reported DE values in term neonates, and our findings appear to be more consistent with some of these [23]. One such study by Laing et al. (1987) was the first to report DE values (4.6\u0026plusmn;0.2 mm) for the right hemi-diaphragm in healthy newborn infants [27].\u0026nbsp;\u003cstrong\u003eSimilarly, Yeung et al.\u0026nbsp;\u003c/strong\u003ereported comparable DE values in term or near term infants (4.4\u0026plusmn;1.6 mm), which were significantly lower than those observed in preterm infants with BPD (6.0\u0026plusmn;1.7 mm)\u0026nbsp;[28]. Another cross-sectional study by\u0026nbsp;\u003cstrong\u003eMartins et al.\u003c/strong\u003e evaluated ultrasound measures of peripheral muscles and diaphragm function in 120 stable preterm and full-term infants. Regarding the diaphragm, significant differences in both thickness and excursion were observed between term infants (DE 4.6\u0026plusmn;3 mm) and very preterm infants. Notably, this is one of the few investigations in the neonatal age to report on DCV, a dynamic ultrasound metric that reflects the speed of diaphragmatic contraction \u0026nbsp;[21].\u0026nbsp;In adults, DCV has been studied as a predictor of successful weaning from mechanical ventilation, though results have been conflicting\u0026nbsp;[29, 30]. In neonates, reduced DCV has been reported in pathological conditions such as patent ductus arteriosus\u0026nbsp;[31]. Findings from the present study suggest that DCV appears to be a robust and consistent parameter in the early neonatal period, with minimal influence from perinatal factors such as mode of delivery or sex. Furthermore, our values are comparable to those reported by Martins et al. for term infants (1.36\u0026plusmn;0.39 cm/s)\u0026nbsp;[21], thereby supporting the notion that diaphragmatic ultrasound may serve as a reliable tool for the assessment of respiratory muscle function in neonatal care.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnderstanding normal diaphragm thickness in healthy term neonates is essential for interpreting respiratory muscle development and function in early life. Rehan et al. examined 16 healthy term infants within two days of birth (one on day 17). Right hemi-diaphragm thickness was measured at inspiration and expiration during quiet sleep in prone and supine positions, with simultaneous cardiorespiratory monitoring. Thickness was significantly greater in the prone position. Reported DTi (2.26\u0026plusmn;0.3 mm) and DTe (1.97\u0026plusmn;0.3 mm) in supine closely resembled our findings [19]. Alonso-Ojembarrena et al. measured 33 preterm and 33 term newborns within 48 hours, reporting lower DTi and DTe in preterms but similar diaphragmatic shortening fractions (a marker of diaphragmatic shortening during inspiration, related to DTF) [20]. Buonsenso et al. defined normal values in 22 healthy infants (7 days\u0026ndash;6 months) [24], \u0026nbsp;while another study in 137 children (0\u0026ndash;8 years) showed higher DTi in infants (\u0026lt;1 year \u0026asymp; 2.07 mm) and DTF \u0026asymp; 25% [25]. Recently, Carvalho et al. examined 100 term neonates (24\u0026ndash;28 hours), providing reference values for DTi, DTe, DTF and DE [23]. \u0026nbsp;Diaphragm thickness in our study aligned with literature and was unaffected by sex or delivery mode whereas thickening fraction remained stable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRight-sided ultrasound is generally preferred across all ages as the liver provides a reliable acoustic window, whereas imaging the left hemi-diaphragm is more challenging due to the smaller spleen window and potential gastric air interference [4, 32]. Unlike most previous studies assessing only the right neonatal hemi-diaphragm, we evaluated both sides. To our knowledge, only one prior neonatal study adopted a similar approach, though it compared preterm and term infants without analyzing side-to-side variation within groups [20]. In our cohort at DOL 1, right-sided DT at inspiration and expiration were slightly higher than left-sided values, though not statistically significant. These small lateral differences likely reflect normal anatomical variation. For both hemi-diaphragms, no significant changes in DT or DTF occurred between DOL 1 and DOL 3, indicating stable diaphragmatic structure and function in healthy term infants during the first 72 hours.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAdditionally, we calculated the side-to-side diaphragmatic thickening fraction difference (\u0026Delta;DTF, %) as an objective, reproducible measure of inter-hemi diaphragmatic performance [33].\u0026nbsp;We observed a minimal mean \u0026Delta;DTF (suggesting a trend for symmetric diaphragmatic function) but marked interindividual variability.\u0026nbsp;\u003cstrong\u003eDuyndam et al evaluating the right hemi-diaphragm in healthy children, reported\u0026nbsp;\u003c/strong\u003eDTF standard deviations \u0026nbsp;from 12.5% (0-6 months) to 10.9% (5-8 years)\u0026nbsp;[25]. In healthy men and women, similar DTF values were observed during quiet and deep breathing, although notable side-to-side differences were present\u0026nbsp;[34]. Importantly, even small absolute differences in thickness (fractions of a millimeter) may translate into appreciable percentage differences. To date, no study has validated a cutoff value for neonatal \u0026Delta;DTF.\u003c/p\u003e\n\u003cp\u003eIn the present study, moderate correlations between DE and DTF were also observed on the left hemi-diaphragm at both DOL 1 and 3, suggesting a functional link between left-sided thickening and diaphragmatic movement. Correlations on the right side were weaker and non-significant, possibly due to greater interindividual variability or technical challenges. As reported by Bahdat et al. in ventilated preterm infants, the liver\u0026rsquo;s supporting effect during inspiration may mask subtle right-sided changes. These anatomical factors likely account for side-to-side differences and highlight the importance of assessing the left hemidiaphragm, which may provide more reliable measurements [35]. Moreover, the absolute thickness change (DTe\u0026ndash;DTi) showed a moderate correlation with DE only on the left side at DOL 1. These findings suggest that DTF may be a more reliable marker of diaphragmatic function in early neonatal life, which may explain why absolute thickness change is rarely reported as a separate measurement [8]. Further research is warranted to clarify the clinical relevance and potential applications of this diaphragmatic parameter.\u003c/p\u003e\n\u003cp\u003eBased on previous studies reporting thinner diaphragm in healthy women than in men [36, 37], we also investigated potential sex-related differences in diaphragmatic function. Although this hypothesis could not be supported in our study, such differences may still emerge under specific pathological conditions. A large analysis in infants with bronchopulmonary dysplasia reported thinner diaphragms in male compared to females [38].\u003c/p\u003e\n\u003cp\u003eIn contrast, we observed that mode of delivery influences diaphragmatic activity. Neonates born vaginally had greater DE and left-sided DTF immediately after birth. By DOL 3, these differences were no longer significant, reflecting early postnatal respiratory adaptation within 48\u0026ndash;72 hours. These findings likely reflect the mechanical and physiological stresses of vaginal delivery and the absence of labor-associated respiratory stimulation in cesarean sections. Although literature on diaphragmatic function by delivery mode is limited, labor and vaginal birth facilitate lung fluid clearance and stimulate spontaneous respiratory efforts [39]. Consequently, reference values for DE and DTF at DOL 1 should consider delivery mode, even though these differences normalize rapidly.\u003c/p\u003e\n\u003cp\u003eIn this context, this study is the first to integrate both DU and LU in healthy term newborns. In critically ill adults, diaphragm dysfunction has been linked to loss of lung aeration and difficult ventilator weaning [40]. \u0026nbsp;Most prior research focused on one modality or preterm/ill infants. A recent prospective study in extremely preterm ventilated infants demonstrated that LU was superior to diaphragmatic indices in predicting extubation success\u0026nbsp;[41]. \u0026nbsp;In our cohort, as expected, we observed low LUS values, reflecting normal lung patterns across all regions and time points, with only minor increases in mild findings in right lower and left lateral fields. These results align with well-aerated lungs after effective postnatal adaptation\u0026nbsp;[42]. Simultaneously, high DTF (~30%) and DE (~4\u0026ndash;5 mm) values indicate strong respiratory muscle function in normal lungs. Interestingly, observed DTF (~30\u0026ndash;34%) exceeded the 20% threshold often used in adult and pediatric studies to indicate dysfunction\u0026nbsp;[35]. suggesting healthy term newborns exhibit robust diaphragmatic contractility.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBeyond the combined use of DU and LU, our study has several strengths. Inclusion of neonates on both DOL 1 and 3 provides rare early-life data, expanding limited evidence on diaphragmatic function in this age group. Bilateral assessments allowed detection of asymmetry potentially missed with right-sided measurements alone. Limitations include the small sample size and follow-up restricted to two early time points. Lastly, all DU measurements were performed by a single investigator. While this minimizes inter-observer variability and ensures consistency, it prevents assessment of reproducibility across operators and may limit generalizability. Recent neonatal studies have shown excellent intra-observer and acceptable inter-observer reproducibility for diaphragmatic shortening fraction in both term and preterm infants [20]. Another study in 2024 reported\u0026nbsp;\u003cstrong\u003egood intrarater and moderate interrater reliability\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003efor the\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ediaphragmatic thickness and mobility\u003c/strong\u003e, while\u0026nbsp;\u003cstrong\u003eDTF interrater reliability was poor\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e[22]\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eFuture studies should enroll larger cohorts with longer follow-up to track diaphragmatic maturation beyond the early neonatal period, ideally through multi-center collaboration. Such investigations should also focus on at-risk neonatal populations to better delineate early-life adaptations and potential long-term consequences. As the diaphragm is a single functional unit but current measurements sample limited sites, standardizing methodology is essential. Future work should compare imaging modalities, assess multiple regions (ZOA and crural), explore novel metrics such as displacement curve area, combined length\u0026ndash;thickness measures, surface variability, and contraction velocity, and integrate automated image analysis to enable broader clinical implementation.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eCombined diaphragm-lung assessment using ultrasound provides valuable insights into early respiratory adaptation and may help establish reference values. In healthy full-term neonates, our study using this dual approach demonstrated stable, robust diaphragmatic function during the first three days of life, with no significant sex-related differences and only a transient effect of delivery mode, with vaginal birth associated with greater diaphragmatic activity compared to cesarean section.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCesarian section (CS)\u003c/p\u003e \u003cp\u003eDay of life (DOL)\u003c/p\u003e \u003cp\u003eDiaphragmatic excursion (DE)\u003c/p\u003e \u003cp\u003eDiaphragmatic thickening fraction (DTF)\u003c/p\u003e \u003cp\u003eDiaphragmatic ultrasound (DU)\u003c/p\u003e \u003cp\u003eDiaphragm contraction velocity (DCV)\u003c/p\u003e \u003cp\u003eDifference in DTF (ΔDTF)\u003c/p\u003e \u003cp\u003eExpiratory diaphragm thickness (DTe)\u003c/p\u003e \u003cp\u003eInspiratory diaphragm thickness (DTi)\u003c/p\u003e \u003cp\u003eInspiratory time (Ti)\u003c/p\u003e \u003cp\u003eLung ultrasound (LU)\u003c/p\u003e \u003cp\u003eLung Ultrasound Score (LUS)\u003c/p\u003e \u003cp\u003eVaginal delivery (VD)\u003c/p\u003e \u003cp\u003eZone of apposition (ZOA)\u003c/p\u003e \u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation and data collection were performed by Ioannis Koutras, Ilias Chatziioannidis, and Angeliki Kontou, while data analysis was conducted by Abraham Pouliakis and Kosmas Sarafidis. The first draft of the manuscript was written by Kosmas Sarafidis, Ioannis Koutras, and Ilias Chatziioannidis, and all authors provided comments on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis observational study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of our Institution (25-09-25/11th\u0026nbsp;session, item 17.).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from the parents of the studies neonates.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank the parents of the enrolled infants for their contributions to this study, as well as the nursing staff at our center for their assistance during the ultrasound examinations.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHiles M, Culpan A-M, Watts C et al (2017) Neonatal respiratory distress syndrome: Chest X-ray or lung ultrasound? A systematic review. 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Pediatr Pulmonol 58:530\u0026ndash;539. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/ppul.26223\u003c/span\u003e\u003cspan address=\"10.1002/ppul.26223\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlank DA, Kamlin COF, Rogerson SR et al (2018) Lung ultrasound immediately after birth to describe normal neonatal transition: an observational study. Arch Dis Child Fetal Neonatal Ed 103:F157\u0026ndash;F162. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/archdischild-2017-312818\u003c/span\u003e\u003cspan address=\"10.1136/archdischild-2017-312818\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Diaphragmatic function metrics on Days of Life (DOL) 1 and 3.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"762\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003e\u0026nbsp;\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 270px;\"\u003e\n \u003ch3\u003e\u003cstrong\u003eDOL 1\u003c/strong\u003e\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 246px;\"\u003e\n \u003ch3\u003e\u003cstrong\u003eDOL 3\u003c/strong\u003e\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 162px;\"\u003e\n \u003ch3\u003e\u003cstrong\u003eDOL 1 vs. DOL 3\u003c/strong\u003e\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003e\u0026nbsp;\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eRight\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003eP1\u003c/p\u003e\n \u003cp\u003eRight vs. Left hemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eRight hemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003eP2\u003c/p\u003e\n \u003cp\u003eRight vs. Left hemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003eP3\u003c/p\u003e\n \u003cp\u003eRight hemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003eP4\u003c/p\u003e\n \u003cp\u003eLeft\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003eDE (mm)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003ch3\u003e4.07\u003c/h3\u003e\n \u003ch3\u003e\u0026nbsp;[3.38, 4.93]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e4.70\u003c/h3\u003e\n \u003ch3\u003e\u0026nbsp;[3.47, 5.26]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.130*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e4.21\u0026nbsp;\u003c/h3\u003e\n \u003ch3\u003e[3.58, 5.04]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e4.61\u0026nbsp;\u003c/h3\u003e\n \u003ch3\u003e[3.54, 5.33]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.546*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.550*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.571*\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003eDCV (mm/sec)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003ch3\u003e9.89\u003c/h3\u003e\n \u003ch3\u003e[8.08, 13.00]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e11.51\u003c/h3\u003e\n \u003ch3\u003e[9.31, 13.19]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.090*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e10.18\u003c/h3\u003e\n \u003ch3\u003e[9.39, 15.26]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e12.44\u003c/h3\u003e\n \u003ch3\u003e[8.83, 16.69]\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.165*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.784*\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.648*\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003eDTi (mm)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003ch3\u003e2.34\u0026plusmn;0.46\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e2.12\u0026plusmn;0.56\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.124\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e2.35 \u0026plusmn;0.47\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e2.12 \u0026plusmn;0.63\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.038\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.921\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.958\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003eDTe\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(mm)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003ch3\u003e1.80 \u0026plusmn;0.34\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e1.67 \u0026plusmn;0.49\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.233\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e1.80 \u0026plusmn;0.40\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e1.59 \u0026plusmn;0.49\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.062\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.974\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.609\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003eDTF (%)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003ch3\u003e30.3\u0026plusmn;13.5\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e29.0\u0026plusmn;11.1\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.710\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e31.7 \u0026plusmn;13.5\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003ch3\u003e33.8 \u0026plusmn;11.8\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.518\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003e0.709\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003e0.218\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003ch3\u003e\u0026Delta;DTF (%)\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 186px;\"\u003e\n \u003ch3\u003e1.4\u0026plusmn;16.1\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003ch3\u003eNA\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 168px;\"\u003e\n \u003ch3\u003e-2.0\u0026plusmn;13.9\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 78px;\"\u003e\n \u003ch3\u003eNA\u003c/h3\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 162px;\"\u003e\n \u003ch3\u003e0.506\u003c/h3\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAll comparisons between paired time points were performed using paired t‑tests, except where data violated normality assumptions\u0026mdash;in those cases (marked with *), the Wilcoxon signed‑rank test was applied and results are presented as median [Q1, Q3].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Diaphragmatic function metrics on Days of Life (DOL) 1 and 3 according to mode of delivery.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"618\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTime point\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSide\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMetrics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVaginal Delivery (n=10)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCesarean Section (n=10)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"11\" style=\"width: 66px;\"\u003e\n \u003cp\u003eDOL 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 96px;\"\u003e\n \u003cp\u003eRight\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDE (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e4.55 [3.94, 5.08]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3.54 [3.09, 4.14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.041\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDCV (mm/sec)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e9.89 [9.14, 11.11]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e9.74 [7.45, 13.23]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.650\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTi (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e2.49\u0026plusmn;0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2.18\u0026plusmn;0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.138\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTe \u003csub\u003e\u0026nbsp;\u003c/sub\u003e(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e1.90\u0026plusmn;0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1.70\u0026plusmn;0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.183\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e30.96\u0026plusmn;12.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e29.69\u0026plusmn;14.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.840\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 96px;\"\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDE (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e5.31 [4.79, 6.46]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3.62 [2.93, 4.48]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDCV (mm/sec)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e11.92 [10.69, 17.71]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e9.57 [7.83, 12.57]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTi (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e2.04\u0026plusmn;0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2.21\u0026plusmn;0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.545\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTe\u003csub\u003e\u0026nbsp;\u0026nbsp;\u003c/sub\u003e(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e1.50\u0026plusmn;0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1.83\u0026plusmn;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.241\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e36.42\u0026plusmn;10.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e21.50\u0026plusmn;5.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 204px;\"\u003e\n \u003cp\u003e\u0026Delta;DTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e-5.467\u0026plusmn;15.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e8.19\u0026plusmn;14.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.056\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"11\" style=\"width: 66px;\"\u003e\n \u003cp\u003eDOL 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 96px;\"\u003e\n \u003cp\u003eRight\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDE (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e4.38 [4.02, 5.27]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3.65 [3.33, 4.35]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.140\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDCV (mm/sec)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e12.08 [9.85, 21.49]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e9.87 [8.92, 11.44]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.290\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTi (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e2.37\u0026plusmn;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2.33\u0026plusmn;0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.855\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTe \u003csub\u003e\u0026nbsp;\u003c/sub\u003e(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e1.78\u0026plusmn;0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1.81\u0026plusmn;0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.884\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e33.67\u0026plusmn;12.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e29.77\u0026plusmn;15.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.534\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" style=\"width: 96px;\"\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003cp\u003ehemi-diaphragm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDE (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e5.01 [3.91, 5.78]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3.95 [3.20, 4.64]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.395\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDCV (mm/sec)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e12.44 [9.62, 15.34]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e12.73 [9.02, 17.82]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTI (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e2.36\u0026plusmn;0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1.87\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.064\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTe\u003csub\u003e\u0026nbsp;\u0026nbsp;\u003c/sub\u003e(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e1.77\u0026plusmn;0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1.41\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.064\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003eDTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e33.34\u0026plusmn;12.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e34.18\u0026plusmn;12.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.877\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 204px;\"\u003e\n \u003cp\u003e\u0026Delta;DTF (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 144px;\"\u003e\n \u003cp\u003e0.33\u0026plusmn;15.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u0026nbsp;-4.42\u0026plusmn;12.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 73px;\"\u003e\n \u003cp\u003e0.460\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAn independent samples t-test or Mann\u0026ndash;Whitney U test was used depending on normality\u003cs\u003e.\u003c/s\u003e Results are reported as mean \u0026plusmn; standard deviation for normally distributed data, or as median and [Q1, Q3] for non-normally distributed data.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpe","sideBox":"Learn more about [European Journal of Pediatrics](https://www.springer.com/journal/431)","snPcode":"431","submissionUrl":"https://submission.nature.com/new-submission/431/3","title":"European Journal of Pediatrics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Diaphragm, Lung, Ultrasound, Adaptation, Neonate","lastPublishedDoi":"10.21203/rs.3.rs-8512179/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8512179/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDiaphragmatic ultrasound (DU) and lung ultrasound (LU) are increasingly applied to evaluate neonatal respiratory muscle performance and lung aeration, respectively. This prospective, observational, single-center study assessed DU of both hemi-diaphragms and lung ultrasound (LU) in healthy full-term neonates on days of life (DOL) 1 and 3 to profile postnatal physiology and establish normative values. DU metrics included diaphragmatic excursion (DE), contraction velocity (DCV), inspiratory diaphragm (DTi) and expiratory diaphragm (DTe) thickness, diaphragmatic thickening fraction (DTF), and inter-hemidiaphragm DTF difference (ΔDTF). LU was performed using a six-zone, three-point scoring system (LUS). Perinatal-neonatal characteristics were recorded. Twenty newborns (10 male, 10 female, mean gestational age 39.0±1.2 weeks, mean birth weight 3334±343 g) were evaluated, with equal distribution between vaginal and cesarean deliveries. No significant differences were observed in DE, DCV, DTi, DTe, or DTF between DOL 1 and 3. Sex had no effect on DU parameters. Cesarean-born neonates demonstrated significantly lower DE and DTF on DOL 1, but values were comparable by DOL 3. LUS was similar between DOL 1 and DOL 3 [medians (Q1–Q3): 1 (0–1.3) and 1 (0–1), respectively, p=0.244], with no differences by delivery mode or sex. \u003cem\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e\u003c/em\u003e Diaphragmatic function is stable in healthy neonates without significant pulmonary involvement on LU during the first three postnatal days. Mode of delivery influences diaphragmatic performance on DOL 1 and should be considered in early assessments. Combined DU and LU provide complementary insights into neonatal respiratory adaptation and may serve as reference values for clinical practice and research.\u003c/p\u003e","manuscriptTitle":"Combined diaphragm and lung ultrasound profiling in healthy full-term neonates: A study of early postnatal function","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-29 00:50:03","doi":"10.21203/rs.3.rs-8512179/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-07T23:39:18+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-05T12:16:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-02T14:36:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"162722487608529803071647123360970675714","date":"2026-01-25T17:47:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"76954396176666697574790358057060565726","date":"2026-01-25T16:25:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"120450896668016184823186280131963219203","date":"2026-01-24T02:15:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-23T16:15:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-22T08:33:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-22T08:13:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Pediatrics","date":"2026-01-04T09:50:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpe","sideBox":"Learn more about [European Journal of Pediatrics](https://www.springer.com/journal/431)","snPcode":"431","submissionUrl":"https://submission.nature.com/new-submission/431/3","title":"European Journal of Pediatrics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ac543405-46b9-4787-b847-0b8074f81c65","owner":[],"postedDate":"January 29th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-23T16:02:57+00:00","versionOfRecord":{"articleIdentity":"rs-8512179","link":"https://doi.org/10.1007/s00431-026-06850-5","journal":{"identity":"european-journal-of-pediatrics","isVorOnly":false,"title":"European Journal of Pediatrics"},"publishedOn":"2026-03-21 15:59:21","publishedOnDateReadable":"March 21st, 2026"},"versionCreatedAt":"2026-01-29 00:50:03","video":"","vorDoi":"10.1007/s00431-026-06850-5","vorDoiUrl":"https://doi.org/10.1007/s00431-026-06850-5","workflowStages":[]},"version":"v1","identity":"rs-8512179","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8512179","identity":"rs-8512179","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}