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The ARRIVE Trial and Professional Guidance: Elective 39 Week Induction to Reduce the Risk of Cesarean Section


The ARRIVE study (A Randomized Trial of Induction Versus Expectant Management), authored by Grobman et al. (NEJM, 2018), was undertaken to determine if elective induction of labor (IOL) of low-risk nulliparous women at 39 weeks reduces adverse perinatal and neonatal morbidity compared to expectant management. SMFM released a statement, endorsed by ACOG, addressing the ARRIVE findings.

SMFM Recommendations

It is reasonable to offer elective IOL to low-risk, nulliparous women at or beyond 39 weeks and 0 days of gestation. We recommend that providers who choose this approach ensure that women meet eligibility criteria of the ARRIVE trial.

We recommend against offering elective IOL to women under circumstances that are inconsistent with the ARRIVE study protocol unless performed as part of research or quality improvement.

We recommend that further research be conducted to measure the impact of this practice in settings other than a clinical trial.

Study Highlights 


    • Multicenter, randomized, controlled, parallel-group, unmasked trial
        • Low-risk nulliparous women between 34w0d-38w6d
        • Live singleton, vertex fetus
        • No contraindications to vaginal delivery
      • No planned cesarean deliver
    • Low-risk
      • No maternal or fetal condition that would be an indication for delivery <40w5d
    • Randomization
        • Induction group: IOL at 39w0d-39w4d
      • Expectant group: No elective delivery <40w5d and begin delivery no later than 42w2d
    • Primary outcome
      • Composite of perinatal death or severe neonatal complications
  • Secondary outcomes
    • Multiple neonatal and maternal outcomes including mode of delivery


    • 3,062 women labor induction group | 3,044 expectant management group
    • Primary outcome not statistically different
      • 4.3% of neonates in induction group vs 5.4% in the expectant group
      • Relative risk (RR) 0.80; 95% CI, 0.64-1.00 (P=0.049)
        • To account for an interim analysis, a two-tailed P value of <0.046 was used for statistical significance threshold
    • Cesarean delivery was less frequent in the induced labor group (19%) vs the expectant management group (22%) 
      • RR 0.84; 95% CI 0.76-0.93
    • Preeclampsia and gestational hypertension occurred in 9.1% of the induced group vs 14.1% of the expectant management group 
      • RR 0.64; 95% CI 0.56-0.74
  • Among newborns, 3% in the induced group needed respiratory support vs 4.2% in the expectant management group
    • RR 0.71; 95% CI 0.55-0.93


  • There was no difference between groups with respect to composite adverse perinatal outcome, but there was reduced frequency of cesarean section in the induction group
  • There was increased incidence of maternal hypertension/preeclampsia and newborn respiratory support in the expectant management group
  • The authors state

Our data suggest that 1 cesarean delivery may be avoided for every 28 deliveries among low-risk nulliparous women who plan to undergo elective induction of labor at 39 weeks.


Induction Protocol Highlights

  • Patients had a cervical exam between 72 hours prior to randomization and 24 hours after randomization
  • IOL protocol
    • Induction using oxytocin
    • Unfavorable cervix (modified Bishop score <5) underwent cervical ripening
      • method left to patient’s physician’s discretion
      • with or followed by oxytocin stimulation
  • ‘Failed’ Labor in latent phase
    • At least 12 hours after completion of cervical ripening, rupture of membranes, and use of a uterine stimulant
    • Cesarean decision left to patient’s physician’s discretion
  • Additional SMFM recommendations
    • Shared decision making is ‘critical’
    • All women in this study had ultrasound dating, early in pregnancy
      • Certain LMP: <21 weeks
      • Uncertain LMP: First trimester ultrasound
  • ACOG has also released a Practice Advisory related to ARRIVE (see ‘Learn More-Primary Sources’ below) that also highlights the importance of shared decision making as well as taking in to account “resources available (including personnel), and the setting in which the intervention will be implemented”

Learn More – Primary Sources:

Labor Induction versus Expectant Management in Low-Risk Nulliparous Women

SMFM Statement: Elective induction of labor in low-risk nulliparous women at term: The ARRIVE trial

ACOG Practice Advisory: Clinical guidance for integration of the findings of The ARRIVE Trial: Labor Induction versus Expectant Management in Low-Risk Nulliparous Women