Iwama N, Sugiyama T, Metoki H, et al. - Researchers conducted this prospective nationwide birth cohort study to explore the connections between glycosylated hemoglobin (HbA1c) levels at less than 24 weeks of gestation and adverse pregnancy outcomes in Japan. The sample consisted of 77,526 patients with an HbA1c level of <6.5% (<48 mmol/mol) at less than 24 weeks of gestation. Using multivariate analyses, correlations of HbA1c level with adverse pregnancy outcomes were assessed. Data reported that the adjusted odds ratios per 1% (11 mmol/mol) increase in HbA1c level were 1.77 for hypertensive disorders of pregnancy; 1.78 for placental abruption; 1.30 for preterm birth; 2.11 for very preterm birth; 1.49 for low birth weight infants; 1.95 for macrosomia; 1.23 for small for gestational age; 1.15 for large for gestational age; and 1.29 for the composite adverse pregnancy outcome. Findings suggested that the higher the HbA1c level, the higher the Japanese risk for adverse outcomes of pregnancy.