Perinatal outcomes in twin pregnancies complicated by gestational diabetes

Gestational diabetes in singleton pregnancies increases the risk for large for gestational age infants, hypertensive disorders of pregnancy, and neonatal morbidity. Compared with singleton gestations, twin gestations are at increased risk for fetal growth abnormalities, hypertensive disorders, and neonatal morbidity. Whether gestational diabetes further increases the risk for these outcomes is unclear.

We sought to determine the relationship between gestational diabetes and the risk for preeclampsia, fetal growth abnormalities, and neonatal intensive care unit admissions in a large cohort of women with twin pregnancies.

We used a retrospective cohort of all twin gestations that were delivered at our institution from 1998 to 2013. We excluded pregnancies delivered before 24 weeks' gestation, monochorionic-monoamniotic twins, and patients with preexisting diabetes for a final cohort of 2573 twin deliveries. Gestational diabetes was defined as 2 abnormal values on a 100 g, 3-hour glucose challenge test as defined by the Carpenter-Coustan criteria or a 1-hour value of 200 mg/dL after a 50 g glucose test. Multivariable Poisson regression models were used to estimate the associations between gestational diabetes and preeclampsia, small for gestational age infants, large for gestational age infants, and admission to the neonatal intensive care unit after adjusting for prepregnancy body mass index, maternal race, maternal age, parity, use of in vitro fertilization, prepregnancy smoking status, and chronic hypertension as confounders.

The unadjusted incidence of gestational diabetes was 6.5% (n=167). Women with gestational diabetes were more likely to be aged 35 years or older, living with obesity, and have conceived via in vitro fertilization than women without gestational diabetes. Preeclampsia was more common among women with twin pregnancies complicated by gestational diabetes (31%) than among women with twin pregnancies without gestational diabetes (18%) (adjusted risk ratio, 1.5; 95% confidence interval, 1.1-2.1). A diagnosis of small for gestational age infant was less common among women with gestational diabetes (17%) than among women without gestational diabetes (24%), although the results were imprecise (adjusted risk ratio, 0.8; 95% confidence interval, 0.5-1.1). There was no association between gestational diabetes and the incidence of large for gestational age neonates or neonatal intensive care unit admissions. Among women with gestational diabetes who reached 35 weeks' gestation, 62% (n=60) required medical management.

Gestational diabetes is a risk factor for preeclampsia among women with twin pregnancies. Close blood pressure monitoring and patient education are critical for this high-risk group. The association between gestational diabetes and neonatal outcomes among women with twin pregnancies is less precise, although it may reduce the incidence of small for gestational age infants. Prospective studies to determine if glycemic control decreases the risk for preeclampsia in twin pregnancies with gestational diabetes are needed.