·To investigate the effect of gestational diabetes mellitus (GDM) on the cortisol level in neonatal umbilical cord blood, and explore the effects of high perinatal cortisol exposure on neonatal health status at preschool-period.

·A total of 170 mothers and their full-term neonates were selected, including 66 cases in GDM group and 104 cases in normal glucose tolerance (NGT) group. The umbilical cord blood from the newborns of the two groups was collected to measure the concentrations of cortisol and adrenocorticotropic hormone (ACTH). SPSS software was used to analyze the effect of GDM on cortisol and ACTH levels in the neonatal umbilical cord blood. Multiple linear regression model was used to analyze the influencing factors of cortisol level in the umbilical cord blood. Pearson χ² method was used to analyze the effects of perinatal high cortisol on the health status of offspring at preschool-period, and binary Logistic regression model was used to analyze the influencing factors of preschool-period obesity.

·Compared with the NGT group, the cortisol level of neonatal umbilical cord blood in the GDM group was higher and ACTH level was lower (both P<0.05). Multiple linear regression analysis showed that maternal gestational times, and blood glucose at 1 h and 2 h after 75 g oral glucose tolerance test (OGTT) were the independent influencing factors of neonatal umbilical cord blood cortisol level (all P<0.05). The follow-up results showed that the offspring with higher perinatal cortisol level had higher pre-school obesity rate (P=0.009). Binary Logistic regression analysis confirmed that neonatal umbilical cord blood cortisol level ≥ 192.00 ng/mL was an independent risk factor of preschool-period obesity (OR=4.714, P=0.016).

·Maternal GDM can cause the increase of neonatal umbilical cord blood cortisol level. High perinatal cortisol exposure can increase the risk of preschool-period obesity in the offspring. GDM may cause long-term diseases in the offspring through perinatal high cortisol exposure.