Gestational diabetes mellitus and late preterm birth: outcomes with and without antenatal corticosteroid exposure

BACKGROUND: Unlike pregestational diabetes mellitus, the American College of Obstetricians and Gynecologists recommends antenatal corticosteroids in those with gestational diabetes mellitus at risk for preterm birth. However, this recommendation is based on limited data, only 10.6% of the Antenatal Late Preterm Steroids study sample had gestational diabetes mellitus. There is a paucity of data on the risk of neonatal respiratory and other morbidity in this population. OBJECTIVE: This study aimed to examine respiratory outcomes in parturients with gestational diabetes mellitus who received antenatal corticosteroids and delivered during the late preterm period vs those who did not. STUDY DESIGN: This population-based cohort study used the US Vital Statistics dataset between 2016 to 2020. The inclusion criteria were singleton, nonanomalous individuals who delivered between 34.0 to 36.6 weeks with gestational diabetes mellitus and known status of antepartum corticosteroid exposure. The primary outcome, a composite neonatal adverse outcome, included Apgar score <5 at 5 minutes, immediate assisted ventilation, assisted ventilation >6 hours, surfactant use, seizure, or neonatal mortality. The secondary outcome was a composite maternal adverse outcome, including maternal blood transfusion, ruptured uterus, unplanned hysterectomy, and admission to the intensive care unit. Multivariable Poisson regression models were used to estimate adjusted relative risks and 95% confidence intervals. Average annual percent change was calculated to assess changes in rates of corticosteroid exposure over the study period. RESULTS: Of 19 million births during the study period, 110,197 (0.6%) met the inclusion criteria, and among them, 23,028 (20.9%) individuals with gestational diabetes mellitus received antenatal corticosteroids. The rate of antenatal steroid exposure remained stable over the 5 years (APC=10.7; 95% confidence interval, −5.4 to 29.4). The composite neonatal adverse outcome was significantly higher among those who received corticosteroids than among those who did not (137.1 vs 216.5 per 1000 live births; adjusted relative risk 1.24; 95% confidence interval, 1.20–1.28). Three components of the composite neonatal adverse outcome—immediate assisted ventilation, intubation >6 hours, and surfactant use—were significantly higher with exposure than without. In addition, the composite maternal adverse outcome was significantly higher among those who received corticosteroids (adjusted relative risk, 1.34; 95% confidence interval, 1.18–1.52). Three components of the composite maternal adverse outcome—admission to intensive care unit, blood transfusion, and unplanned hysterectomy—were significantly higher among the exposed group. Subgroup analysis, among large for gestational age, by gestational age, and race and ethnicity, confirm the trend of increased likelihood of adverse outcomes with exposure to corticosteroid. CONCLUSION: Individuals with gestational diabetes mellitus and antenatal corticosteroid exposure, who delivered in the late preterm, were at higher risk of neonatal and maternal adverse outcomes than those unexposed to corticosteroid.