Maternal saliva visfatin level in term and preterm labor: A case control study.

Nicotinamide Phosphoribasyl Transferase (NAmPRtase or NampT) or Pre-B-cell Colony Enhancing Factor 1 (PBEf1) or visfatin is a protein mainly produced in visceral fat tissue. Visfatin is also found in skeletal muscles, liver, bone marrow and lymphocytes. The role of visfatin has been demonstrated in regulating cell growth, apoptosis and angiogenesis in mammalian cells [ 1 – 3 ]. Visfatin is a multi-functional inflammatory mediator that can play roles such as growth factor, enzyme or cytokine in different situations in the body [ 4 ]. Visfatin is related to the occurrence of several inflammatory diseases and also imitates a role similar to insulin [ 5 ]. The concentration of visfatin in saliva or serum increases in many inflammatory, infectious or immunodeficiency diseases, including periodontal diseases, diabetes, cardiovascular diseases, etc. [ 6 ]. Today, a high percentage of pregnant women experience premature labor, which is called preterm labor, and this problem causes many problems for both the mother and her premature baby such as mortality and morbidity [ 7 ]. Premature birth means delivery before the 37th week of pregnancy [ 8 ]. Premature birth is one of the main causes of death in infants without abnormalities, and after birth defects, it is the second cause of infant death, which imposes a high economic and psychological cost on the society [ 9 ]. Premature birth is an adverse event pregnancy outcome worldwide with a prevalence of 15 million per year [ 10 ]. Various factors, including the advanced maternal age [ 11 – 13 ] and infection [ 14 – 16 ], history of still birth, miscarriage, preeclampsia , placenta previa and multiple pregnancy [ 15 ] play a role in preterm delivery. Visfatin plays a role as a regulator of immune responses and infection-related inflammations, and especially visfatin increases in cases of premature delivery caused by amnionitis [ 17 ]. It has been reported that the concentration of visfatin in umbilical cord blood is lower in preterm fetuses than in term fetuses, and visfatin in maternal and fetal circulation may play an important role in the occurrence of preterm birth or premature rupture of fetal membranes [ 18 ]. The detection of diagnostic biomarkers for the early identification of groups with high-risk preterm birth, to prevent the birth of premature babies, which incur a lot of economic and psychological costs on the society, is of particular importance. Based on this and since there has not been a study to investigate the level of maternal saliva visfatin of women with premature birth, and the role of visfatin as a multi-functional mediator, in this study we aimed to compare the level of maternal saliva visfatin in premature delivery women with women with term delivery.

In this case-control study, 40 pregnant mothers in each group (preterm and term) were included in the analysis. The comparison of the two groups in terms of demographic and clinical variables is shown in Table 1 . The analysis did not show any significant difference between the two groups in terms of mean age (p = 0.296), place of residence (p = 0.469), occupation (p = 0.898) and education level (p = 0.968). Regarding the clinical variables, the distribution of endometriosis (p = 0.237), PCO (p = 0.454), history of surgery (p = 0.745), preeclampsia (p = 0.530), pre pregnancy BMI (p = 0.061) and type of delivery (p>0.999) was similar between the two groups. Meanwhile, the prevalence of GDM in the pre-term group was significantly (P = 0.009) higher than the group of term infants (37.5% vs. 12.5%). In addition, the mean weight gain during pregnancy in the term delivery group was significantly higher than the pre-term delivery group, which is due to premature delivery (p = 0.024). The characteristics of babies were compared between the two groups in Table 2 . The results showed that the mean height (p = 0.001) and head circumference (p = 0.001) of infants in the term delivery group is significantly higher than the preterm group. Also, in term of gender, the percentage of girl babies in the preterm group was higher than that in term group (p = 0.007). Maternal saliva visfatin level was compared between two groups. The results revealed that the mean maternal saliva visfatin in the preterm group (4.75±2.2) is significantly (p = 0.001) lower than that in term birth group (6.7±3.1) ( Fig 1 ) (mean difference: -1.98, 95%CI: -3.16, -0.79). The results of adjusted logistic regression revealed that after adjusting for GDM, preeclampsia, pre pregnancy BMI and weight gain, the mean of maternal saliva visfatin level in the preterm group is significantly lower than that in the term group (p = 0.026). Additional analyzes showed that the mean level of maternal saliva visfatin in women with GDM, preeclampsia and SGA was lower in compared to non-affected women, while this observed difference was not significant ( Table 3 ) . SD: Standard deviation, CI: Confidence interval

Considering that during the term pregnancy visfatin levels increase and visfatin may play a role in initiating labor, in our study due to the high visfatin level in case group although the level of maternal saliva visfatin was lower than the control group but high levels of visfatin in the case group can represent the role of visfatin in initiating labor and due to this issue can be use the role of this adipokine for early diagnosis of preterm delivery can be used to prevent, treat and improve the prognosis of this disease. Also, this study is the first study to compare the maternal saliva visfatin between SGA and AGA group and there is no difference between this groups.

This study is a case-control study. In this study, women who were admitted to Taleghani Hospital (Arak, Iran, 2021) due to spontaneous premature delivery were included in the study. Their criteria for spontaneous premature delivery were confirmed by a gynecologist or senior gynecology resident. A detailed examination of teeth and gum diseases was performed by a dentist. The case group includes women who gave birth before 37 weeks of pregnancy and the control group includes women who gave birth after 37 weeks of pregnancy. This study has been approved by the Ethics Committee of Arak University of Medical Science with ID: IR.ARAKMU.REC.1399.346. The authors had access to information that could identify individual participants during the data collection but after that, the data coded and access to information that could identify individual participants was limited to supervisor. These women were included in the study after being approved by an assistant gynecologist by checking the inclusion criteria. The inclusion criteria included the following: women with premature labor and term delivery, having informed consent to participate in the study, natural pregnancy (not assisted reproductive technology), singleton pregnancies, absence of systemic diseases such as metabolic syndrome, diabetes mellitus, autoimmune disorders, acute and chronic infections, malignancies, heart diseases, liver diseases, etc., not using cigarettes, absence of chorioamnionitis, absence of connective tissue diseases and gum diseases and not using drugs that affect fat metabolism, such as steroids and systemic retinoids. In all participants, labor had started spontaneously and iatrogenic preterm birth were not included in the study. Patients’ recruitment was lasted from March 2021 to August 2021. To saliva sampling, the participants asked to avoid food and water for at least 2 hours before taking the saliva sample. To obtain a saliva sample, we first ask the participants to swish 10 sterile normal saline solutions in their mouth for 60 seconds. Next, check the person’s mouth to make sure there are no food or water residues. Then, we ask the participant to suck a 1*1 cm piece of paraffin for 90 seconds and then pour 5 ml of his saliva sample into a sterile, dry polyethylene vial. Finally, the obtained samples are quickly transferred to the freezer or -70°C temperature. The samples obtained from the saliva of the subjects in the study were evaluated using the ELISA method. Currently, the only test that is accurate and scientific, does not need to spend a lot of time and money, and it is easier than other tests due to the lack of complex and expensive devices is an ELISA test. This test is similar to other Radio Immuno Assay tests in terms of working, but instead of radioisotope, the color reaction caused by the effect of the enzyme on the substrate is used as an indicator. The intensity of the color also depends on the concentration of the antigen, and usually an ELISA reader is used to measure the intensity of the color created, and the amount of liquid in each absorbent paper is measured using calibrated device (Periotron TM 6000 Proflow Inc, Amityville, NY, USA). To determine the required sample size, type one error was considered as 0.05, study power 90%, and based on a study conducted by Pavlová et al. [ 18 ], mean maternal visfatin concentration in the group with term delivery was considered as 1.70 ± 0.91 and in preterm birth women 2.83 ± 1.95 ng/ml. The required sample size of each group was 40 woman and a total of 80 people were included. Mean, standard deviation, count and percentage were used to describe the data. Likelihood ratio Chi-square tests, independent two samples t-test and logistic regression analysis were used to compare the desired variables between the two groups. Statistical tests were performed at a significance level of 0.05 using Stata software version 14 (Stata Corp, College Station, TX, USA).

(XLSX) Click here for additional data file.