Does Routine Induction at 39 Weeks Improve Outcomes?

by | May 3, 2022 | Induction of Labor

A recent systematic review (a study of studies) challenges current wisdom that inducing at 39 weeks reduces cesareans and improves newborn outcomes.5

Reviewers pooled data among 16 randomized controlled trials (studies in which participants are assigned by chance to one form of treatment or another), comprising 8796 pregnancies in all, in which participants with no medical indication for induction were assigned to either routine induction at 39 to 40 weeks or to “expectant management.”

With respect to maternal outcomes, they found similar rates of:

  • cesarean delivery
  • instrumental vaginal delivery
  • excessive postpartum blood loss
  • need for blood transfusion

Regarding newborn outcomes, they found similar rates of:

  • perinatal mortality (death around the time of birth)
  • admission to a newborn intensive care nursery
  • poor condition at birth (Apgar score less than 7 at 5 minutes)
  • chorioamnionitis (inflammation of the amniotic membranes)

Reviewers found an increase in diagnoses of high blood pressure in the expectantly managed pregnancies. This, though, as the reviewers note, is a subjective diagnosis, which downgrades its importance. It’s also a diagnosis that may be used as a means of getting around prohibitions against elective induction of labor.4

They also found an increase in meconium-stained amniotic fluid. While meconium (the baby’s first stool) in the amniotic fluid can lead to a rare and potentially serious complication when distress provokes unborn babies to inhale meconium-containing amniotic fluid, meconium staining by itself merely indicates a maturing digestive tract.

Henci comments:

The review reported these results despite including the ARRIVE trial, a large trial concluding that routinely inducing 1st-time mothers at 39 weeks reduces cesareans and improves newborn outcomes.6 The ARRIVE trial’s results are driving the push to make 39-week induction the norm.

The ARRIVE trial has many weaknesses, and I have written about them here.  The disproof of the pudding, though, is this: participants in the ARRIVE trial were ultra-low-risk 1st-time mothers, that is, they would have been eligible for birth center or home births. The ARRIVE trial reported a 19% cesarean rate in the group induced at 39 weeks compared with a 22% rate, or 3 more per 100, in women “expectantly managed.” This is the grounds on which routine 39-week induction was judged superior. In contrast, however, birth center and home birth studies report cesarean rates ranging from 8% to 13% in similar women,1-3, 7-12 or 6 to 11 fewer cesareans per 100 than the 19% reported with 39-week induction.

The ARRIVE trial also reported that 12% of babies in the routine induction group were admitted to special care nurseries. You would expect that a few babies would need stepped up care after birth even in the healthiest of populations, but more than one in ten? That seems shockingly high.    

As I wrote in my critique, routine induction at 39 weeks seems superior only by virtue of being the “frying pan” compared with the expectant management “fire.” Step outside of the “kitchen” of usual obstetric management, and it dismally fails the test.


1.    Bailey DJ. Birth outcomes for women using free-standing birth centers in South Auckland, New Zealand. Birth 2017;44(3):246-51.

2.    Birthplace in England Collaborative Group. Perinatal and maternal outcomes by planned place of birth for healthy women with low risk pregnancies: the Birthplace in England national prospective cohort study. BMJ 2011;343:d7400.

3.     Bovbjerg ML, Cheyney M, Brown J, et al. Perspectives on risk: Assessment of risk profiles and outcomes among women planning community birth in the United States. Birth 2017.

4.    Clark SL, Simpson KR, Knox GE, et al. Oxytocin: new perspectives on an old drug. Am J Obstet Gynecol 2009;200(1):35 e1-6.

5.    Dong S, Bapoo S, Shukla M, et al. Induction of labour in low-risk pregnancies before 40 weeks of gestation: A systematic review and meta-analysis of randomized trials. Best Pract Res Clin Obstet Gynaecol 2022;79:107-25.

6.    Grobman WA, Rice MM, Reddy UM, et al. Labor Induction versus Expectant Management in Low-Risk Nulliparous Women. N Engl J Med 2018;379(6):513-23.

7.    Hutton EK, Cappelletti A, Reitsma AH, et al. Outcomes associated with planned place of birth among women with low-risk pregnancies. CMAJ 2015.

8.    Janssen PA, Saxell L, Page LA, et al. Outcomes of planned home birth with registered midwife versus planned hospital birth with midwife or physician. CMAJ 2009;181(6-7):377-83.

9.    Johnson KC, Daviss BA. Outcomes of planned home births with certified professional midwives: large prospective study in North America. BMJ 2005;330(7505):1416-22.

10.  Jolles DR, Langford R, Stapleton S, et al. Outcomes of childbearing Medicaid beneficiaries engaged in care at Strong Start birth center sites between 2012 and 2014. Birth 2017;44(4):298-305.

11.  Nethery E, Schummers L, Levine A, et al. Birth Outcomes for Planned Home and Licensed Freestanding Birth Center Births in Washington State. Obstet Gynecol 2021;138(5):693-702.

12.  van der Hulst LA, van Teijlingen ER, Bonsel GJ, et al. Does a pregnant woman’s intended place of birth influence her attitudes toward and occurrence of obstetric interventions? Birth 2004;31(1):28-33.

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