At what gestational age should delivery be planned for a singleton pregnant woman with gestational diabetes mellitus and well‑controlled glucose (fasting <95 mg/dL, 2‑hour post‑prandial <120 mg/dL) and no other obstetric complications?

Timing of Delivery for Gestational Diabetes Mellitus

For a singleton pregnancy with well-controlled gestational diabetes (diet-controlled, fasting <95 mg/dL, 2-hour postprandial <120 mg/dL) and no other complications, delivery should be planned during the 39th week of gestation (39 0/7 to 39 6/7 weeks). 1, 2

Evidence-Based Delivery Timing

The American College of Obstetricians and Gynecologists specifically recommends the 39th week window for women with diet-controlled GDM who maintain good glycemic control without maternal vascular complications 1. This timing provides the optimal balance between preventing fetal macrosomia and avoiding prematurity-related neonatal morbidity 2.

Key Principles

• Do not deliver before 38 completed weeks based solely on GDM diagnosis, as delivery before 38 weeks increases neonatal morbidity without maternal or fetal benefit 1, 3, 4

• Delivery at 38 weeks may be considered in some guidelines to prevent progressive macrosomia, though the strongest current recommendation supports 39 0/7 to 39 6/7 weeks for uncomplicated, diet-controlled cases 3, 4

• GDM alone is never an indication for cesarean delivery - mode of delivery should follow standard obstetric indications 1, 3, 4

Pre-Delivery Assessment Requirements

Before finalizing delivery plans, the following assessments are mandatory:

• Ultrasound for estimated fetal weight (EFW) - if EFW exceeds 4,500 grams, discuss risks and benefits of scheduled cesarean delivery due to significantly increased shoulder dystocia and brachial plexus injury risk 1, 3, 2

• Confirm adequate glycemic control with targets of fasting <95 mg/dL and either 1-hour postprandial <140 mg/dL or 2-hour postprandial <120 mg/dL 5, 3

• Assess for any maternal vascular complications or other obstetric complications that would alter timing 1

Clinical Surveillance Strategy

For women with well-controlled diet-managed GDM approaching term:

• Continue glucose monitoring through delivery planning to ensure maintenance of glycemic targets 5

• Increased surveillance becomes critical if fasting glucose levels begin to exceed targets or pregnancy progresses past 39 6/7 weeks 1

• Fetal surveillance starting at 32 weeks is suggested for patients requiring medications, though this may not be necessary for well-controlled diet-managed cases 2

Critical Pitfalls to Avoid

• Never deliver before 38 weeks solely for GDM diagnosis - prolongation past 38 weeks may increase macrosomia risk, but premature delivery increases neonatal respiratory distress, hypoglycemia, and NICU admission 1, 3, 4

• Do not perform cesarean delivery based on GDM diagnosis alone - this is emphasized across all major guidelines as a critical error 1, 3, 4

• Do not use estimated fetal weight <4,500 grams as cesarean indication - only weights exceeding 4,500 grams warrant discussion of elective cesarean 1, 2

Postpartum Management

After delivery, essential follow-up includes:

• Reclassification of glucose tolerance at 4-12 weeks postpartum using 75g oral glucose tolerance test with non-pregnancy criteria 5, 3, 4

• Lifelong diabetes screening every 1-3 years as women with GDM have a sevenfold increased risk of developing type 2 diabetes 5, 4, 6

• Encourage breastfeeding and lifestyle modifications to reduce subsequent diabetes risk 3, 4