Higher odds of gestational diabetes among women with multiple pregnancies: a nationwide register-based cohort study in Finland

INTRODUCTION: The association between multiple pregnancies and the risk of gestational diabetes mellitus (GDM) has been moderately studied. The aim of this study is to evaluate whether women with multiple pregnancies are at a higher risk of developing GDM using nationwide high-quality registers. MATERIALS AND METHODS: In this retrospective cohort study, data from the National Medical Birth Register (MBR) was used to evaluate the odds of GDM as a result of multiple pregnancies. We included all pregnancies with a tested GDM recorded in the MBR between 2004 and 2018. A total of 397,810 pregnancies were included in this study. Logistic regression model was used to assess the odds for GDM among multiple pregnancies, when compared to singleton pregnancies. Odds ratios (ORs) and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) between the groups were compared. The model was adjusted with maternal BMI and in vitro fertilisation (IVF) treatments. RESULTS: A total of 5825 multiple pregnancies and a tested GDM were observed. In the control group, there were 391,985 singleton pregnancies with a tested GDM. Of these, 1791 (30.7%) multiple pregnancies were associated with a diagnosis of GDM. GDM was more common among women with multiple pregnancies (30.7 vs. 25.9%, aOR 1.28; CI 1.21–1.36). CONCLUSION: The results of this study show that women with multiple pregnancies have a higher odds of developing GDM and should be monitored to prevent the development of GDM. SUPPLEMENTARY INFORMATION: This article belongs in the Topical Collection "Pregnancy and Diabetes" managed by Antonio Secchi and Marina Scavini. The online version contains supplementary material available at 10.1007/s00592-022-01984-y.