Should I Agree to Induction for a Big Baby?

You ask:

My doctor said the ultrasound showed my baby is getting quite big. She says inducing now would avoid a c-section. I’m worried about getting induced, but I don’t want a c-section either. Should I agree?

I answer:

The research says “No.” The purpose of inducing for suspected big baby, aka macrosomia, which means “big body,” is to avoid a cesarean and also to avoid injury to you or your baby during a difficult vaginal birth. In order to accomplish that, the following would have to be true:

1. Doctors would need to be able to accurately identify which babies are going to be big. They can’t. “Big,” is usually defined as weighing 8 lb 13 oz (4,000 g) or more. Ultrasound scans predicting that a baby will weigh more than 4,000 g will be right only 56 percent of the time.² That means you have roughly a 50:50 chance of being induced for a problem you don’t have.
2. Inducing labor would need to reduce cesareans. It doesn’t. For one thing, every study that has looked at outcomes when a baby is predicted to be big has found that when doctors think the baby is going to be big, the odds of cesarean go up markedly regardless of whether the baby is actually on the large side.^{4, 7, 10, 12, 13, 15, 17, 19} The reverse is also true: cesarean rates with babies who are big, but doctors didn’t suspect it, are much lower. In other words, the belief that the baby will be too big to birth vaginally can become a self-fulfilling prophecy. For another, none of the studies that have looked at whether inducing for suspected big baby reduced cesareans have found that it did.^{3, 14, 18} Furthermore, one study that looked at first births only reported a substantial increase in cesareans with induction.^{1, 11} Looking at mixed populations where some were having first babies and others had previous vaginal births may have masked this effect because first labors are much more vulnerable to factors that inhibit progress, of which induction is one.
3. Inducing labor would need to reduce birth injuries. It doesn’t do that either. The only protective effect of inducing for suspected big baby is a possible small reduction in the incidence of broken collarbone, an injury that will heal without further consequence. That protection is offset by a probable slight increase in the occurrence of maternal anal sphincter injury, an injury that increases the probability of developing chronic incontinence of gas or stool.^{3, 11, 13, 17-19} In other words, there is a possible modest reduction in infant fractures, which have no long term consequences, that is offset by an increase in maternal anal sphincter tears, which can.

If you would like more in-depth information than I’ve provided here, Evidence-Based Birth has an excellent article on this topic.

Your Take-Away

Unfortunately, you have a problem whether you decide to agree to induction or wait for labor. If your care providers fear that you won’t be able to birth a bigger baby or birth one without injury, you’re already behind the 8-ball because it will affect their judgment and the calls they make. Here are some thoughts about how best to protect yourself:

• If possible, switch to care providers who believe you can birth a bigger baby. They will also be more likely to have policies and practices that promote your ability to birth a bigger baby, e.g., encouraging mobility in labor and pushing and birth positions other than on your back, evaluating your progress on an individual basis, not according to rule, etc.
• Take a set of childbirth classes intended to prepare you to labor without an epidural. You can still decide you want one in labor, but epidurals inhibit mobility (see the previous bullet) and slow labor, and you’ll learn strategies to help you manage without one.
• Hire a doula. A doula will have ideas to help you progress in labor and can also keep up your and your partner’s spirits if you experience self-doubt or negativity from medical staff.
• Decline a cesarean or instrumental vaginal delivery based solely on exceeding a preset time limit. That decision should be based on an evaluation of how well you and your baby are tolerating labor, what’s been tried to improve labor or pushing progress, and what progress you’ve made.
• Should you decide induction is your best option, wait until the cervix is favorable for labor (Bishop score 8 or higher). In first births, studies consistently find that with an unfavorable cervix, cesarean rates with induction greatly exceed rates when labor starts on its own despite use of cervical ripening agents whereas rates are similar when the cervix is favorable.^{5, 6, 8, 9, 16}
• Decline rupture of membranes as part of a labor induction. Once membranes are ruptured, you are committed to the birth. If membranes are intact and the induction doesn’t “take,” you can quit, go home, and try again another day.

References

1. Prevention of perinatal group B streptococcal disease: a public health perspective. Centers for Disease Control and Prevention. MMWR Recomm Rep 1996;45(RR-7):1-24.
2. ACOG. Macrosomia: ACOG Practice Bulletin, Number 216. Obstet Gynecol 2020;135(1):e18-e35.
3. Boulvain M, Irion O, Dowswell T, et al. Induction of labour at or near term for suspected fetal macrosomia. Cochrane Database Syst Rev 2016(5):CD000938.
4. Cheng ER, Declercq ER, Belanoff C, et al. Labor and Delivery Experiences of Mothers with Suspected Large Babies. Matern Child Health J 2015;19(12):2578-86.
5. Dunne C, Da Silva O, Schmidt G, et al. Outcomes of elective labour induction and elective caesarean section in low-risk pregnancies between 37 and 41 weeks’ gestation. J Obstet Gynaecol Can 2009;31(12):1124-30.
6. Gibson KS, Waters TP, Bailit JL. Maternal and neonatal outcomes in electively induced low-risk term pregnancies. Am J Obstet Gynecol 2014;211(3):249 e1- e16.
7. Goer H. Induction of labor: Patience is a virtue. In: Goer H, Romano A, eds. Optimal Care in Childbirth: The Case for a Physiologic Approach. Seattle, WA: Classic Day Publishing; 2012.
8. Laughon SK, Zhang J, Grewal J, et al. Induction of labor in a contemporary obstetric cohort. Am J Obstet Gynecol 2012;206(6):486 e1-9.
9. Le Ray C, Carayol M, Breart G, et al. Elective induction of labor: failure to follow guidelines and risk of cesarean delivery. Acta Obstet Gynecol Scand 2007;86(6):657-65.
10. Matthews KC, Williamson J, Gupta S, et al. The effect of a sonographic estimated fetal weight on the risk of cesarean delivery in macrosomic and small for gestational-age infants(). J Matern Fetal Neonatal Med 2017;30(10):1172-6.
11. Moldeus K, Cheng YW, Wikstrom AK, et al. Induction of labor versus expectant management of large-for-gestational-age infants in nulliparous women. PLoS One 2017;12(7):e0180748.
12. Papaccio M, Fichera A, Nava A, et al. Obstetric consequences of a false-positive diagnosis of large-for-gestational-age fetus. Int J Gynaecol Obstet 2022;158(3):626-33.
13. Peleg D, Warsof S, Wolf MF, et al. Counseling for fetal macrosomia: an estimated fetal weight of 4,000 g is excessively low. Am J Perinatol 2015;32(1):71-4.
14. Sanchez-Ramos L, Bernstein S, Kaunitz AM. Expectant management versus labor induction for suspected fetal macrosomia: a systematic review. Obstet Gynecol 2002;100(5 Pt 1):997-1002.
15. Scifres CM, Feghali M, Dumont T, et al. Large-for-Gestational-Age Ultrasound Diagnosis and Risk for Cesarean Delivery in Women With Gestational Diabetes Mellitus. Obstet Gynecol 2015;126(5):978-86.
16. Vahratian A, Zhang J, Troendle JF, et al. Labor progression and risk of cesarean delivery in electively induced nulliparas. Obstet Gynecol 2005;105(4):698-704.
17. Vendittelli F, Riviere O, Breart G, et al. Is prenatal identification of fetal macrosomia useful? Eur J Obstet Gynecol Reprod Biol 2012;161(2):170-6.
18. Vendittelli F, Riviere O, Neveu B, et al. Does induction of labor for constitutionally large-for-gestational-age fetuses identified in utero reduce maternal morbidity? BMC Pregnancy Childbirth 2014;14:156.
19. Vitner D, Bleicher I, Kadour-Peero E, et al. Does prenatal identification of fetal macrosomia change management and outcome? Arch Gynecol Obstet 2019;299(3):635-44.

Medical Disclaimer: Henci Goer is neither a physician nor a midwife. Content and information on this website are for informational and educational purposes only and do not constitute medical advice. Users are advised to consult their physician or midwife when making decisions about care.