What is the optimal gestational age for women with gestational diabetes type A1 to deliver?

Type A1 gestational diabetes mellitus (A1GDM), also known as diet-controlled gestational diabetes, is associated with an increase in adverse perinatal outcomes such as macrosomia and Erb palsy. However, it remains unclear when to deliver these women because optimal timing of delivery requires balancing neonatal morbidities from early term delivery against the risk of intrauterine fetal demise (IUFD). We sought to determine the optimal gestational age (GA) for women with A1GDM to deliver.

A decision-analytic model was built to compare the outcomes of delivery at 37-41 weeks in a theoretical cohort of 100,000 women with A1GDM. Strategies involving expectant management until a later GA accounted for probabilities of spontaneous delivery, indicated delivery, and IUFD during each week. GA-associated risks of neonatal complications included cerebral palsy, infant death, and Erb palsy. Probabilities were derived from the literature, and total quality-adjusted life years were calculated. Sensitivity analyses were used to investigate the robustness of the baseline assumptions.

Our model showed that induction at 38 weeks maximized quality-adjusted life years. Within our cohort, delivery at 38 weeks would prevent 48 stillbirths but lead to 12 more infant deaths compared to 39 weeks. Sensitivity analysis revealed that 38 weeks remains the optimal timing of delivery until IUFD rates fall <0.3-fold of our baseline assumption, at which point expectant management until 39 weeks is optimal.

By weighing the risks of IUFD against infant deaths and neonatal morbidities from early term delivery, we determined that the ideal GA for women with A1GDM to deliver is 38 weeks.