Adverse obstetric outcomes in early‐diagnosed gestational diabetes mellitus: The Japan Environment and Children’s Study

AIMS/INTRODUCTION: To examine adverse outcomes in women with early‐diagnosed gestational diabetes mellitus using data from a large birth cohort study in Japan. MATERIALS AND METHODS: This study analyzed data from singleton pregnancies in the Japan Environment and Children’s Study including births during 2011–2014. Mothers with an HbA1c level ≥6.5% in the first trimester, a history of diabetes mellitus, or steroid use during pregnancy were excluded. The participants were divided into three groups: control (without gestational diabetes mellitus), early‐diagnosed gestational diabetes mellitus (diagnosed before gestational week 24), and late‐diagnosed gestational diabetes mellitus (diagnosed after gestational week 24). Multiple logistic regression analysis was performed to calculate the risk of early‐diagnosed and late‐diagnosed gestational diabetes mellitus for adverse obstetrics outcomes. RESULTS: In total, 100,376 eligible participants were included in this study. The number of individuals in control cases, early‐diagnosed gestational diabetes mellitus cases, and late‐diagnosed gestational diabetes mellitus cases was 98,090 (97.7%), 751 (0.7%), and 1,535 (1.5%), respectively. When control cases were used as reference, multiple logistic regression analysis revealed that early‐diagnosed gestational diabetes mellitus increased the risk of hypertensive disorders of pregnancy (adjusted odds ratio: 2.08, 95% confidence interval: 1.51–2.86), early‐onset hypertensive disorders of pregnancy (adjusted odds ratio: 1.91, 95% confidence interval: 1.01–3.65), and late‐onset hypertensive disorders of pregnancy (adjusted odds ratio: 1.92, 95% confidence interval: 1.29–2.86). CONCLUSION: Early‐diagnosed gestational diabetes mellitus is associated with serious obstetric complications. Our findings indicate the necessity of further investigations to validate the benefit of early screening for gestational diabetes mellitus in pregnant women.