Association between obstructive sleep apnea and perinatal outcomes in a cohort of Japanese pregnant women: a prospective observational study

PURPOSE: Obstructive sleep apnea (OSA) is common during pregnancy, and maternal intermittent hypoxemia has been suggested to affect fetal growth. However, diagnosis-based risk assessment and research in East Asian pregnant women remain insufficient. In this study, we aimed to clarify the prevalence of sleep-disordered breathing in Japanese pregnant women and to examine its association with neonatal outcomes. METHODS: We included 185 pregnant women aged ≥ 20 years and their newborns. A questionnaire was administered, and sleep evaluation was performed using a portable monitoring device (WatchPAT) at ≥ 28 weeks of gestation. OSA severity was classified, based on the apnea-hypopnea index (AHI), as mild (5 ≤ AHI < 15), moderate (15 ≤ AHI < 30), and severe (AHI ≥ 30). Neonatal physical growth was evaluated at birth and compared between the OSA (AHI ≥ 5) and non-OSA groups. RESULTS: The prevalence of OSA (AHI ≥ 5) was 15.7%, comprising 23 mild (5 ≤ AHI < 15), 5 moderate (15 ≤ AHI < 30), and 1 severe (AHI ≥ 30) cases. Pre-pregnancy weight and body mass index (BMI) were significantly higher in the OSA group than in the non-OSA group, whereas the rate of BMI change during pregnancy was significantly lower. Regarding neonatal outcomes, no significant differences in physical growth or gestational age at delivery were observed between the two groups. CONCLUSION: This study provides insights into the phenotype of pregnancy-related OSA in a lean Japanese population, where OSA may develop at lower BMI levels than those reported in Western cohorts.