Previous induced abortion or miscarriage is associated with increased odds for gestational diabetes: a nationwide register-based cohort study in Finland

Aims: The aim of this study was to investigate the association between previous induced abortion or miscarriage and the development of gestational diabetes mellitus (GDM) using high-quality register data. Methods: In this retrospective nationwide register-based cohort study, data from the national medical birth register (MBR) were used to evaluate the association between a history of miscarriage or induced abortion and GDM. We included all first pregnancies ending in delivery in which the oral glucose tolerance test was performed between 2004 and 2018. A logistic regression model was used to assess the development of GDM in the first pregnancy ending in delivery. Adjusted odds ratios (aOR) with 95% confidence intervals (Cis) were compared between groups. Results: In total, 15,873 nulliparous women with a history of induced abortions, 22,337 with a history of miscarriages and 3594 with a history of both were found. The reference group consisted of 138,869 women without a history of induced abortions or miscarriages. Women with a history of induced abortions (24.7%, aOR 1.15 [CI 1.11–1.20]), a history of miscarriages (24.8%, aOR 1.14 [CI 1.10–1.18]) and a history of both (27.7% aOR 1.18 [CI 1.09–1.28]) had higher odds for the development of GDM when compared to the reference group (20.8%). The odds for GDM increased along with the increasing number of previous induced abortions and miscarriages. Conclusion: Women with a history of induced abortions or miscarriages had higher odds for GDM in their first pregnancy leading to birth. Knowledge of this association will be helpful in the prevention and screening of GDM.