From the Guidelines
Induction of labor is not routinely indicated for suspected large for gestational age (LGA) fetuses to prevent shoulder dystocia. While it may seem logical that delivering a baby before it grows larger would reduce the risk of shoulder dystocia, evidence does not strongly support this approach for all LGA pregnancies 1. The American College of Obstetricians and Gynecologists (ACOG) recommends that suspected fetal macrosomia is not an indication for induction of labor, as it does not improve maternal or fetal outcomes 1.
Key Considerations
- Induction may be considered in specific circumstances, such as when the estimated fetal weight exceeds 4500g in diabetic mothers or 5000g in non-diabetic mothers, as these thresholds are associated with significantly higher risks of shoulder dystocia and birth trauma 1.
- If induction is pursued, standard methods including cervical ripening with prostaglandins (misoprostol or dinoprostone), mechanical dilation with a Foley catheter, or oxytocin administration may be used depending on cervical readiness.
- The decision should be individualized and made after discussing the benefits and risks with the patient, including the increased likelihood of cesarean delivery (particularly in nulliparous women with unfavorable cervix) and the potential benefits of avoiding further fetal growth 1.
- It's also important to note that ultrasound estimation of fetal weight has limitations with error margins of ±10-15%, which can lead to unnecessary interventions for falsely diagnosed LGA fetuses.
Risks and Benefits
- Risks of induction include increased likelihood of cesarean delivery and potential fetal injuries such as fracture of the clavicle and damage to the nerves of the brachial plexus 1.
- Potential benefits include avoiding further fetal growth and reducing the risk of shoulder dystocia, although the evidence does not strongly support this approach for all LGA pregnancies 1.
From the Research
Induction of Labor for Suspected LGA Fetuses
- The induction of labor for suspected Large for Gestational Age (LGA) fetuses is a topic of ongoing debate in the medical community, with some studies suggesting it may help prevent shoulder dystocia 2, 3.
- A study published in 2021 found that current data indicate a significant proportion of babies are LGA, and pregnancies involving LGA babies are associated with increased maternal and perinatal morbidity, including caesarean section, postpartum hemorrhage, shoulder dystocia, and birth trauma 2.
- Another study published in 2025 found that induction of labor between 38+0 weeks' gestation and 38+4 weeks' gestation did show a significant reduction in shoulder dystocia in the per-protocol analysis, but not in the intention-to-treat analysis 3.
Benefits and Risks of Induction of Labor
- Induction of labor for suspected fetal macrosomia has been shown to reduce the risk of shoulder dystocia and fracture, but may also lead to longer labours and an increased risk of caesarean section 4.
- A study published in 2023 found that diabetes increased the risk of shoulder dystocia, even at lower birth weight thresholds than at which cesarean delivery is currently offered, and that cesarean delivery for suspected macrosomia may have decreased the risk of shoulder dystocia at higher birth weights 5.
- The Cochrane review published in 2023 found that induction of labour for suspected fetal macrosomia results in a lower mean birthweight, and fewer birth fractures and shoulder dystocia, but may not alter the risk of brachial plexus injury or caesarean delivery 4.
Clinical Practice Recommendations
- Existing guidelines do not support routine induction of labor in suspected LGA fetuses, and the decision to induce labor should be made on a case-by-case basis, taking into account individual patient factors and preferences 2, 4.
- The American College of Obstetricians and Gynecologists (ACOG) recommends that women with suspected fetal macrosomia be counseled about the risks and benefits of induction of labor and cesarean delivery, and that the decision to induce labor be made on a case-by-case basis 4.
- Further trials of induction shortly before term for suspected fetal macrosomia are needed to refine the optimum gestation of induction and improve the accuracy of the diagnosis of macrosomia 4.