(930) Glycemic Status and Fetal Growth in Twin Gestations

Objective: In this study, we compared fetal growth curves in twin pregnancies affected by gestational diabetes with normoglycemic twin pregnancies. We hypothesized that fetal growth curves in twin gestations affected by gestational diabetes mellitus (GDM) would be significantly different from fetal growth curves for normoglycemic twin gestations, given the well-established fetal growth acceleration which occurs in singleton pregnancies affected by GDM.

Study Design: This study is a secondary analysis of a retrospective cohort study of twin pregnancies conducted at 17 centers in the US. Our primary exposure group was GDM, and our primary outcome was estimated fetal weight (EFW) as a function of gestational age. Dichorionic twin pregnancies with data from at least one ultrasound were included in the study. Demographic data were collected and compared between the two groups. The means of EFW at each gestational week were calculated for both groups, plotted onto curves, and subsequently compared.

Results: Our results demonstrated no statistically significant difference between groups in terms of demographic characteristics. However, the comparison between fetal growth curves also revealed no significant difference between the two groups, so we were unable to reject our null hypothesis after this initial analysis of the primary outcome.

Conclusion:
We aimed to evaluate the association of GDM with longitudinal fetal growth in twin pregnancies. Contrary to our hypothesis, we did not find a statistically significant difference in longitudinal fetal growth between normoglycemic twin pregnancies and twin pregnancies affected by GDM. These results are not entirely inconsistent with what has been demonstrated in prior literature; namely, that GDM likely does not affect fetal growth in twin pregnancies nearly as dramatically as it has been shown to affect fetal growth in singleton pregnancies. This may be because any accelerated growth caused by GDM in twins would be masked by the expected growth deceleration that has been demonstrated in twins in the third trimester.