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

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.

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.

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).

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.