Twin pregnancies complicated by gestational diabetes mellitus: a single centre cohort study

Aims In women with a twin pregnancy, to determine the incidence of, risk factors for and outcomes of women with gestational diabetes mellitus, and assess how these have changed with a change in gestational diabetes screening. Methods Retrospective cohort study of women with a twin pregnancy attending an Australian tertiary hospital, 2002–2013. Information on gestational diabetes status, gestational diabetes risk factors and pregnancy outcomes was ascertained. Pregnancy outcomes included hypertensive disorders, twin birthweight centile and a composite adverse pregnancy outcome. Analysis was stratified pre/post screening protocol change (epoch 1: 2002–2009, epoch 2: 2010–2013) and by gestational diabetes status. Results Gestational diabetes was diagnosed in 86/982 (8.8%) women, increasing from 4.4% to 14.7% between epochs (P = 0.0001). The proportion of women with hypertensive disorders increased (11.7% vs. 13.4%, P = 0.009), but the proportion of infant's birthweight > 90th centile decreased (11.0% vs. 7.6%, P = 0.02) between epochs. Overall, 33.6% of women had ≥ 1 risk factors for gestational diabetes. Three‐quarters (73.7%) of women overall had an adverse pregnancy outcome, with a slightly higher proportion in women with gestational diabetes compared with those with no gestational diabetes (79.7% vs. 73.1%, P = 0.06). The rate of the adverse pregnancy outcome did not change by epoch, after adjusting for maternal and pregnancy risk factors (adjusted odds ratio = 0.96, 95% confidence interval 0.73–1.26). Conclusions Almost 1 in 10 women with a twin pregnancy were diagnosed with gestational diabetes, with the incidence of gestational diabetes increasing threefold with a new screening protocol. The pregnancy outcomes of women with a twin pregnancy did not change with increased detection and treatment for gestational diabetes. What's new? Rates of gestational diabetes in twin pregnancy increased threefold from 4.4% to 14.7% with a change towards universal early pregnancy glucose‐tolerance testing. Adverse pregnancy outcomes in twin pregnancies did not change with increased screening and treatment of gestational diabetes, although there was a decrease in large for gestational age infants. Nearly half of women with a twin pregnancy had risk factors for gestational diabetes, apart from twin pregnancy.