What are the recommended delivery procedures for a macrosomic baby?

Delivery Management for Macrosomic Baby

Trial of labor with vaginal delivery is recommended for suspected macrosomic fetuses, with the specific approach determined by estimated fetal weight, maternal diabetes status, and labor progress. 1

Approach Based on Estimated Fetal Weight and Diabetes Status

For Non-Diabetic Mothers:

• Labor and vaginal delivery are NOT contraindicated for estimated fetal weights up to 5,000 g (11 lb). 1
• Prophylactic cesarean delivery may be considered only when estimated fetal weight exceeds 5,000 g. 1
• Trial of labor is safe for estimated fetal weights over 4,000 g based on large cohort studies. 1

For Diabetic Mothers:

• Prophylactic cesarean delivery may be considered when estimated fetal weight exceeds 4,500 g. 1
• The risk of shoulder dystocia increases dramatically to 19.9-50% when birth weight exceeds 4,500 g in diabetic pregnancies. 1

Critical Management Principles During Labor

Induction of Labor:

• Do NOT induce labor solely for suspected macrosomia—induction doubles the cesarean delivery risk without reducing shoulder dystocia or improving neonatal outcomes. 1, 2
• Randomized trials show similar cesarean rates (19.4% vs 21.6%) and shoulder dystocia rates between induction and expectant management groups. 1

Important caveat: One 2015 trial by Boulvain et al. showed conflicting results, suggesting induction at 37-38 weeks for suspected macrosomia >95th percentile reduced shoulder dystocia (2% vs 6%) without increasing cesarean rates. 3 However, the ACOG guidelines (which represent broader consensus) do not support routine induction. 1

Operative Vaginal Delivery:

• Avoid midpelvic operative vaginal delivery (forceps/vacuum) in suspected macrosomia. 1
• Forceps delivery carries a fourfold increased risk of persistent birth injury compared to spontaneous vaginal delivery or cesarean section. 4
• Cesarean delivery should be performed for midpelvic arrest with suspected macrosomia, except in extreme emergencies. 1

Second Stage Management:

• With estimated fetal weight >4,500 g, prolonged second stage or arrest of descent in the second stage is an indication for cesarean delivery. 1

Preparation for Shoulder Dystocia

The most serious complication is shoulder dystocia, occurring in 1.4% of all vaginal deliveries but increasing to 9.2-24% in non-diabetic women and 19.9-50% in diabetic women when birth weight exceeds 4,500 g. 1

Essential preparations:

• Have an experienced obstetrician present for delivery. 5
• Prepare for shoulder dystocia maneuvers before delivery begins. 5, 6
• Ensure neonatal resuscitation team availability. 5
• Counsel patient about 10-fold increased risk of clavicular fracture and 18-21-fold increased risk of brachial plexus injury when birth weight exceeds 4,500 g. 1

Cesarean Section Considerations

If cesarean delivery is performed:

• Ensure the incision is large enough to avoid difficult abdominal delivery. 1
• Prophylactic cesarean for suspected macrosomia <5,000 g (non-diabetic) or <4,500 g (diabetic) is NOT supported by cost-effectiveness data—it would require 148-258 cesarean sections to prevent one persistent birth injury. 1, 4

Common Pitfalls to Avoid

• Do not rely solely on ultrasound for weight estimation—accuracy is no better than clinical palpation (Leopold's maneuvers). 1
• Do not perform elective induction before 39 weeks due to neonatal respiratory complications. 2
• Do not use misoprostol for cervical ripening if the patient has had a prior cesarean delivery. 2
• Vaginal delivery results in less maternal morbidity (26% perineal trauma, 4% postpartum hemorrhage) compared to cesarean delivery (32% postpartum hemorrhage). 7