Impact of Prepregnancy Maternal Fasting Glucose Levels on Pregnancy and Neonatal Morbidity in Women With Pregestational Diabetes Mellitus

Background: Managing blood glucose levels before conception and during pregnancy is crucial for ensuring optimal maternal and fetal outcomes. However, little is known about the impact of maintaining fasting plasma glucose (FPG) levels within a specific range on pregnancy and neonatal morbidities, especially in women with diabetes mellitus (DM). We aimed to evaluate the effects of maternal prepregnancy FPG levels on pregnancy and neonatal morbidity in women with pregestational DM. Methods: This retrospective nationwide study included singleton pregnant women diagnosed with DM who underwent health screening. We compared the risk of adverse pregnancy outcomes (APOs) and neonatal morbidity based on prepregnancy FPG levels. Multivariate analyses were performed to estimate odds ratios for the risk of APOs and neonatal morbidity. Results: A total of 7,542 women were included in the analysis. After adjusting for covariates, as FPG levels increased, there was a tendency for a higher risk of preterm birth, macrosomia, and large-for-gestational-age (LGA) babies. Compared to mothers with FPG levels below 85 mg/dL, pregestational FPG ≥ 126 mg/dL was associated with an increased risk of neonatal morbidities such as transient tachypnea of the newborn (TTN), respiratory distress syndrome (RDS), and neonatal hypoglycemia. Conclusion: Elevated prepregnancy FPG levels were associated with higher frequencies of preterm birth, macrosomia, and LGA. Neonates born to women with diabetes-range FPG had higher rates of TTN, RDS, and neonatal hypoglycemia. Prospective longitudinal studies incorporating both prepregnancy and gestational glycemic status are needed to establish the causal relationship between glycemic control and pregnancy outcomes in women with diabetes.