999: The Impact of Gestational Diabetes in Twin Pregnancies on Maternal and Neonatal Outcomes

Abstract

Studies of gestational diabetes (GDM) in twin pregnancies are limited by small sample size and unknown chorionicity. We sought to determine how rates of GDM vary by chorionicity and determine the impact of GDM on maternal and neonatal outcomes in a large cohort of well-characterized twin pregnancies. This is a retrospective cohort study of all twin deliveries from Magee-Womens Hospital, University of Pittsburgh between 1998 and 2013. Monochorionic monoamniotic twins were excluded. Maternal and neonatal data were collected using a perinatal database, chart abstraction, and placental review. Large and small for gestational age (LGA/SGA) were defined as less than 10% using the NICHD growth study. Given the limited number of monochorionic diamniotic (mono/di) twins with GDM, univariate and multivariable logistic regression were used to interrogate the association between GDM and perinatal outcomes among dichorionic twins. Given GDM is a maternal exposure, analysis was done at the maternal level and outcomes reported are for either baby. Prepregnancy body mass index, race, parity, maternal age and type of assisted reproductive technology were included as potential confounders. 2927 twin pregnancies were included in the cohort: 79.4% (n=2323) were dichorionic and 20.6% (n=604) were mono/di. The median gestational age at delivery was 36 weeks (IQR: 33.4,37.5). 23.6% of women were obese, 468 (16%) conceived with in vitro fertilization and the average age was 30 years (+/-5.8y). The overall rate of GDM was 6.4% (n=188) and there was no difference in rate of GDM by chorionicity with 154 (6.6%) cases in di/di twins and 34 (5.6%) cases in mono/di twins (p=0.47). Among dichorionic twins, GDM was associated with an increased risk of preeclampsia with an OR = 2.0 (CI: 1.4, 2.8; p<0.001). After adjusting for confounders, this remained significant with an aOR = 1.6 (CI:1.1, 2.3, p=0.02). Among dichorionic twins, GDM was not associated with an increased risk of cesarean delivery, LGA, SGA, or admission to the NICU for either twin (Table 1). The rate of GDM in this cohort was similar to rates in singleton pregnancies. Dichorionic twin pregnancies affected by GDM have an increased risk of preeclampsia compared to twin pregnancies without GDM. Neonatal outcomes were not different. Future studies to determine if glycemic control modifies these associations are needed.