Relationship between weight gain of mothers during pregnancy and gestational age at birth

Various factors such as maternal weight gain during pregnancy are important in the occurrence of preterm birth. Among these, the role of maternal weight gain during pregnancy is less studied. The present study was performed with aim to determine the relationship between maternal pre-pregnancy weight, body mass index and gestational age at birth.
In this cross-sectional study which was conducted in Tehran in July 2015, a total of 5170 deliveries were examined of which 77 cases were twin pregnancy and excluded from the study and finally, 5093 were analyzed. The data related to pregnancy and delivery in 103 hospitals was collected by 103 trained midwives by using a designed questionnaire. Data analysis was performed by Stata software (version 13), and descriptive statistics methods and linear simple regression. P Multiple linear regression analysis revealed that weight gain during pregnancy was significantly associated with gestational age at birth (P=0.001), so that for every one unit increase in weight gain during pregnancy, gestational age at birth increases 0.052 weeks (95% CI: 0.036-0.068 weeks) (P=0.001) and the chance of preterm labor decreases, but maternal weight (P=0.818), height (P=0.894) and body mass index (P=0.991) were not significantly associated with gestational age.
Weight gain during pregnancy is of the important factor in gestational age at birth, so that appropriate weight gain during pregnancy leads to reduced preterm birth in pregnant women.