Risk of gestational diabetes in women with PCOS based on body mass index: The Japan Environment and Children's Study.

Context: Women with polycystic ovary syndrome (PCOS), which is the most common endocrine disorder in women of reproductive age, have a potentially increased risk of gestational diabetes mellitus (GDM).
Objective: To examine the impact of PCOS on GDM based on maternal body mass index (BMI) using data from a large birth cohort study in Japan.
Design: Prospective observational study using data from the Japan Environment and Children's Study (JECS).
Participants: Singleton pregnancies in the JECS during 2011-2014 were included. Mothers with HbA1c levels of ≥6.5% in the first trimester and history of DM or steroid use during pregnancy were excluded.
Main Outcome Measures: Participants were categorized according to their pre-pregnancy BMIs: G1 (<18.5 kg/m2), G2 (18.5-19.99 kg/m2), G3 (20.0-22.99 kg/m2), G4 (23.0-24.99 kg/m2), and G5 (≥25.0 kg/m2). The impact of PCOS on early (Ed) and late-onset (Ld) GDM for each group was estimated using a multiple logistic regression model.
Results: We included 92774 participants, comprising 2012 PCOS(+) cases. GDM occurrence was higher in women with PCOS (p<0.001). PCOS had no effect on GDM in G1, G2, and G3. In G4, PCOS increased the risk of Ed GDM (adjusted odds ratio [aOR]: 3.27, 95% confidence interval [CI]: 1.29-8.29). In G5, PCOS increased the risk of both Ed (aOR: 2.48, 95% CI: 1.53-4.02) and Ld GDM (aOR: 1.94, 95% CI: 1.23-3.07).
Conclusions: The impact of PCOS on GDM occurrence depended on the pre-pregnancy BMIs, which may facilitate personalized preconception counseling among women with PCOS.
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