Jacqueline Ruplinger, MD

Evidence summary

The definition of macrosomia is fetal weight of 4000 to 4500 g or greater, regardless of gestational age. This differs from “large for gestational age,” which is a birth weight greater than 90th percentile for a given gestational age. Ten percent of all US live born infants weigh more than 4000 g, and 1.5% weigh more than 4500 g.¹ Detection of fetal macrosomia is difficult, because there are no reliable methods for determining EFW. Ultrasound estimate of fetal weight may be less accurate than estimates by multiparous patients and clinicians using Leopold maneuvers.² Ultrasound prediction of EFW in babies 4500 g or larger can be off by as much as 13%.¹ The purpose of induction for fetal macrosomia would be to prevent maternal and neonatal morbidities. However, studies have shown that the incidence of cesarean and instrumented deliveries was not decreased, and perinatal morbidity was not changed.³ To date, there are only 2 randomized controlled trials comparing expectant management with induction of labor for suspected fetal macrosomia.

Gonen and colleagues⁴ followed 273 women at 38 weeks or more with ultrasound-determined fetal weights between 4000 and 4500 g. Women were excluded if they had diabetes, noncephalic presentations, a previous cesarean delivery, or other indications for induction. The induction group received either prostaglandin or pitocin for induction, depending on cervical status. Patients in the expectant management group were induced at 42 weeks. There was no change in cesarean delivery rate or in neonatal morbidity.

Tey and coworkers⁵ randomized 40 women who did not have diabetes at 37 to 42 weeks with EFWs between 4000 and 4500 g to induction versus expectant management. Induction was performed with prostaglandin if the cervix was unfavorable (Bishop score <6), followed by pitocin. Women were excluded if there was an indication for delivery at the time of enrollment. There was no statistical difference in the cesarean delivery rate or incidence of shoulder dystocia between the 2 groups.

Recommendations from others

An American College of Obstetrics and Gynecology Practice Bulletin states the position that there is no role for induction of labor in term women with suspected fetal macrosomia. This recommendation is based on the difficulty of accurate assessment of fetal weight and additional case-control evidence suggesting that induction increases the risk of cesarean delivery without improving maternal or fetal outcomes.

Evidence summary

The definition of macrosomia is fetal weight of 4000 to 4500 g or greater, regardless of gestational age. This differs from “large for gestational age,” which is a birth weight greater than 90th percentile for a given gestational age. Ten percent of all US live born infants weigh more than 4000 g, and 1.5% weigh more than 4500 g.¹ Detection of fetal macrosomia is difficult, because there are no reliable methods for determining EFW. Ultrasound estimate of fetal weight may be less accurate than estimates by multiparous patients and clinicians using Leopold maneuvers.² Ultrasound prediction of EFW in babies 4500 g or larger can be off by as much as 13%.¹ The purpose of induction for fetal macrosomia would be to prevent maternal and neonatal morbidities. However, studies have shown that the incidence of cesarean and instrumented deliveries was not decreased, and perinatal morbidity was not changed.³ To date, there are only 2 randomized controlled trials comparing expectant management with induction of labor for suspected fetal macrosomia.

Gonen and colleagues⁴ followed 273 women at 38 weeks or more with ultrasound-determined fetal weights between 4000 and 4500 g. Women were excluded if they had diabetes, noncephalic presentations, a previous cesarean delivery, or other indications for induction. The induction group received either prostaglandin or pitocin for induction, depending on cervical status. Patients in the expectant management group were induced at 42 weeks. There was no change in cesarean delivery rate or in neonatal morbidity.

Tey and coworkers⁵ randomized 40 women who did not have diabetes at 37 to 42 weeks with EFWs between 4000 and 4500 g to induction versus expectant management. Induction was performed with prostaglandin if the cervix was unfavorable (Bishop score <6), followed by pitocin. Women were excluded if there was an indication for delivery at the time of enrollment. There was no statistical difference in the cesarean delivery rate or incidence of shoulder dystocia between the 2 groups.

Recommendations from others

An American College of Obstetrics and Gynecology Practice Bulletin states the position that there is no role for induction of labor in term women with suspected fetal macrosomia. This recommendation is based on the difficulty of accurate assessment of fetal weight and additional case-control evidence suggesting that induction increases the risk of cesarean delivery without improving maternal or fetal outcomes.

Evidence summary

The definition of macrosomia is fetal weight of 4000 to 4500 g or greater, regardless of gestational age. This differs from “large for gestational age,” which is a birth weight greater than 90th percentile for a given gestational age. Ten percent of all US live born infants weigh more than 4000 g, and 1.5% weigh more than 4500 g.¹ Detection of fetal macrosomia is difficult, because there are no reliable methods for determining EFW. Ultrasound estimate of fetal weight may be less accurate than estimates by multiparous patients and clinicians using Leopold maneuvers.² Ultrasound prediction of EFW in babies 4500 g or larger can be off by as much as 13%.¹ The purpose of induction for fetal macrosomia would be to prevent maternal and neonatal morbidities. However, studies have shown that the incidence of cesarean and instrumented deliveries was not decreased, and perinatal morbidity was not changed.³ To date, there are only 2 randomized controlled trials comparing expectant management with induction of labor for suspected fetal macrosomia.

Gonen and colleagues⁴ followed 273 women at 38 weeks or more with ultrasound-determined fetal weights between 4000 and 4500 g. Women were excluded if they had diabetes, noncephalic presentations, a previous cesarean delivery, or other indications for induction. The induction group received either prostaglandin or pitocin for induction, depending on cervical status. Patients in the expectant management group were induced at 42 weeks. There was no change in cesarean delivery rate or in neonatal morbidity.

Tey and coworkers⁵ randomized 40 women who did not have diabetes at 37 to 42 weeks with EFWs between 4000 and 4500 g to induction versus expectant management. Induction was performed with prostaglandin if the cervix was unfavorable (Bishop score <6), followed by pitocin. Women were excluded if there was an indication for delivery at the time of enrollment. There was no statistical difference in the cesarean delivery rate or incidence of shoulder dystocia between the 2 groups.

Recommendations from others

An American College of Obstetrics and Gynecology Practice Bulletin states the position that there is no role for induction of labor in term women with suspected fetal macrosomia. This recommendation is based on the difficulty of accurate assessment of fetal weight and additional case-control evidence suggesting that induction increases the risk of cesarean delivery without improving maternal or fetal outcomes.