Same disease - different effect: maternal diabetes impact on birth weight stratified by fetal sex.

Background: Male-sex is an independent risk factor for adverse perinatal outcomes. One example is gestational diabetes mellitus (GDM), which is associated with large gestational age neonates. It was previously described that fetal glucose metabolism is affected by fetal sex.

Purpose: To examine whether the birth weight of neonates is affected differently by GDM according to fetal sex.

Methods: A retrospective normalized cohort analysis, using the open database of 2017 Natality Data from the National Vital Statistics System in the US. We compared the delta in neonatal birth weight, according to fetal sex, between pregnancies with or without GDM. Linear regression was used to take into consideration the effect of multiple confounders. For evaluation whether fetal sex is an independent risk factor for macrosomia (> 4000 and > 4500 g) following pregnancies complicated by GDM we used multivariate logistic regression.

Results: A significant relationship was found between the sex of the neonate and the delta in birth weight associated with GDM (P-value < 0.0001). The average weight gain in neonates to GDM pregnancies was 71 g in females, and 56 g in males. The prevalence of macrosomia above 4000 g and 4500 g that was attributed to GDM was higher in female-sex neonates compared to male-sex neonates (P < 0.05).

Conclusion: According to our study results, female sex is associated with higher fetal weight gain in pregnancies complicated by GDM. Moreover, macrosomia's rate (> 4000 g and > 4500 g) attributed to GDM raised in a more significant manner in female-sex neonates.