Association of History of Spontaneous or Induced Abortion With Subsequent Risk of Gestational Diabetes

IMPORTANCE: Gestational diabetes (GD) is one of the most common and important complications of pregnancy. Identifying pregnant women who are at high risk of GD is crucial for implementing early prevention and intervention. OBJECTIVE: To examine whether a history of spontaneous abortion (SAB) or induced abortion is associated with increased risk of GD in subsequent pregnancies. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study was conducted at a tertiary hospital in Shanghai, China. Pregnant women who received routine antenatal care between January 2014 and December 2019 were included. Data analysis was performed from December 2020 to June 2021. EXPOSURES: Maternal history of abortion, including SAB and induced abortion, were extracted from medical records. MAIN OUTCOMES AND MEASURES: GD was diagnosed with a 75-g diagnostic oral glucose tolerance test. A multivariable-adjusted log-binomial analysis was used to estimate relative risks (RRs) and 95% CIs of GD associated with history of abortion. RESULTS: Among the 102 259 included pregnant women (mean [SD] age, 29.8 [3.8] years), 14 579 (14.3%) experienced only SAB, 17 935 (17.5%) experienced only induced abortion, and 4017 (3.9%) experienced both SAB and induced abortion. A total of 12 153 GD cases were identified, and the prevalence of GD was 11.9% (12 153 of 102 259 women) in this cohort. Pregnant women who experienced only SAB (RR, 1.25; 95% CI, 1.18-1.31) or both SAB and induced abortion (RR, 1.15; 95% CI, 1.05-1.27) were at higher risk of developing GD. The association of SAB history with GD occurred in a number-dependent manner. Compared with pregnant women with no history of abortion, the RR for GD increased by 18% (RR, 1.18; 95% CI, 1.11-1.26) for pregnant women with 1 SAB, by 41% (RR, 1.41; 95% CI, 1.27-1.57) for those with 2 SABs, and by 43% (RR, 1.43; 95% CI, 1.22-1.67) for those more than 2 SABs. However, no association between history of induced abortion and GD was observed. CONCLUSIONS AND RELEVANCE: This study found that a history of SAB was associated with increased risk of GD in subsequent pregnancies. Further research is needed to clarify this association and explore the potential biological mechanisms underlying the association.