BACKGROUND AND PURPOSE:

• There is lack of agreement regarding the amount of time required before labelling an induction of labor as ‘failed’
• Grobman et al. (AJOG, 2018) assessed adverse maternal and neonatal outcomes in nulliparous women associated with the duration of the latent phase

METHODS:

• Observational Cohort Study
  • NICHD MFMU (APEX study; 2008-2011)
  • Obstetric cohort of nulliparous women who had a term (≥37 weeks) singleton gestation in the cephalic presentation and underwent a labor induction
• Latent phase
  • Start time: Once cervical ripening has ended (no longer used), oxytocin has been initiated, and rupture of membranes had occurred (spontaneous or artificial)
  • End time: Once 5-cm dilation occurred
• Primary perinatal outcomes (as a function of the duration of the latent phase)
  • Frequency of cesarean delivery
  • Adverse maternal outcomes
• Primary neonatal outcome defined as a composite of the following, including any
  • Seizures
  • Culture-proven sepsis
  • Bone or nerve injury
  • Encephalopathy
  • Death

RESULTS:

• 10,677 women were included in the analyses
  • 1725 (16.2%) underwent induction for PROM
  • 5582 (52.3%) underwent cervical ripening
• Approximately 2/3 of women had progressed to active labor by 6 hours
• 96.4% of women progressed to active phase by 15 hours
• The longer the latent phase, the greater the chance of cesarean delivery (P <.001)
  • >40% of women whose latent phase lasted ≥18 hours still had a vaginal delivery
• With longer latent phase, frequency was increased for
  • Postpartum hemorrhage (P <.001)
  • Chorioamnionitis (P <.001)
  • PPH (P <.001)
• Frequency of adverse neonatal outcomes were stable and did not differ over time including
  • Primary composite neonatal outcome
  • Low Apgar score
  • Acidemia
  • Shoulder dystocia
• NICU admission did increase with duration of latent phase

CONCLUSION:

• The frequency of adverse maternal outcomes increased as the latent phase lengthened
• The absolute risk of adverse maternal outcomes was relatively small
• This study suggests that cesarean delivery should not be opted for until 15 hours after administered oxytocin and rupture of membranes
• Following 15 hours, management should be individualized

Learn More – Primary Sources:

Defining failed induction of labor

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Cochrane Review 2017: Outpatient Cervical Ripening and Labor Induction

Induction to Prevent Stillbirths for Age 35 and Older: Impact on Cesarean Rates?

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