Objective: Gestational diabetes mellitus (GDM) in singleton pregnancy is associated with large for gestational age (LGA) neonates and adverse perinatal outcomes; however, the impact of GDM in twin pregnancy is unclear. Thus, the aim of the present study was to assess the perinatal outcomes of twin pregnancies complicated by GDM by performing a meta-analysis of observational studies.

Data Sources and Study Selection: An online search of three databases: Medline, Embase and Web of Science was carried out to identify full paper observational studies (retrospective or prospective) published in English that examined GDM in twin pregnancy compared with non-GDM twin pregnancy and reported on birth weight and/or adverse perinatal outcomes.

Data Synthesis: Data extraction included general study characteristics, maternal demographics and perinatal outcomes. Random-effects models with inverse variance weighting were used to calculate standardised mean differences and unadjusted odds ratios (OR). Sensitivity analyses were carried out to determine the impact of possible maternal confounders on perinatal outcomes.

Results: Fourteen observational studies were included. GDM twins were born at the same gestation as non-GDM twins, with slightly lower birth weight (2,461.4 g vs. 2,476.2 g, respectively; p < 0.0001). There was no increased risk of LGA for GDM twins in both unadjusted and adjusted (for maternal BMI and age) analyses. Conversely, GDM in twin pregnancy was associated with a lower risk of small for gestational age neonates (OR 0.84; 95% CI 0.81, 0.87; p < 0.0001) in the unadjusted analysis alone. Although there was no correlation between GDM in twin pregnancy and respiratory distress, neonatal hypoglycaemia or low Apgar score, GDM twins had a higher rate of NICU admission (OR 1.49; 95% CI 1.10, 2.02; p < 0.01).

Conclusions: Identification and subsequent treatment of GDM in twin pregnancy demonstrates a similar risk of adverse perinatal outcomes compared to non-GDM twin pregnancies.