Maternal Glucose, Cortisol, and Neonatal Outcomes With and Without GDM

This study will compare maternal blood glucose and cortisol responses and neonatal outcomes between women with gestational diabetes mellitus and women without gestational diabetes mellitus who receive epidural analgesia during labor. The study will be conducted at three hospitals in Hanoi, Vietnam. Maternal blood glucose will be measured repeatedly during labor, and cortisol will be measured before epidural analgesia and 2 hours later. Neonatal assessments will include umbilical cord arterial blood gas analysis, blood glucose measurements after birth, and clinical outcomes. Other maternal factors, including body temperature and labor course, will also be recorded.

* Inclusion Criteria: * Age 18 to 40 years. * Singleton pregnancy with cephalic presentation and gestational age 37 to 42 weeks. * Planned vaginal delivery. * Cervical dilatation of 3 to 4 cm at epidural catheter placement. * American Society of Anesthesiologists physical status I or II. * Request for and written informed consent to epidural labor analgesia and study participation. * Gestational diabetes mellitus group: gestational diabetes mellitus diagnosed using a 75-g, 2-hour oral glucose tolerance test according to national guidance and managed with diet and exercise without insulin during labor. * Non-gestational diabetes mellitus group: negative 75-g, 2-hour oral glucose tolerance test during the same pregnancy. * Exclusion Criteria: * Pre-existing type 1 or type 2 diabetes mellitus, or gestational diabetes mellitus requiring insulin treatment. * Endocrine disorders that affect cortisol or glucose metabolism, including Cushing syndrome or adrenal insufficiency. * Severe preeclampsia or eclampsia; complete placenta previa; previous uterine scar; threatened uterine rupture; fetal growth restriction; or severe polyhydramnios or oligohydramnios. * Severe or decompensated medical disease. * Systemic corticosteroid use, with the most recent dose administered within 72 hours before labor. * Contraindication to epidural analgesia or refusal of the procedure.