BACKGROUND AND PURPOSE:

• New 2014 labor management guidelines (ACOG and SMFM)
  • Active phase of labor: >6 cm dilation vs >4 cm
  • Arrest of dilation: (1) No cervical change despite 4 hours of adequate uterine contractions or (2) No cervical change despite 6 hours of oxytocin administration with inadequate uterine activity
• Govindappagari et al. (Obstetrics & Gynecology, 2019) assessed whether protracted active phase >6 hours as associated with increased risk for adverse perinatal outcomes

METHODS:

• Retrospective cohort study
• Participants
  • Nulliparous | Term | Singleton | Vertex
  • In active phase (using >6 cm definition)
• Comparison of 2 groups
  • Normal active phase
    • Cervical change 1 cm or more within 4 hours throughout active labor
  • Mildly protracted active phase
    • Cervical change ≤1 cm over 4 to 6 hours
  • Very protracted active phase
    • Cervical change ≤1 cm over 6 hours
• Study design and data analysis
  • Rate of change was assessed between cervical examinations
  • Regression analyses were performed to compare maternal and neonatal outcomes by study group
• Primary outcome
  • A composite of maternal morbidity
  • Morbidities included: Maternal fever from chorioamnionitis or endometritis | PPH | Transfusion | Postpartum length of stay >5 days
• Secondary outcome
  • A composite of neonatal morbidity
  • Morbidities included: NICU admission | Fever | Sepsis | RDS | Transient tachypnea of the newborn | 5-minute Apgar ≤3 | HIE | Therapeutic hypothermia | Intubation | Length of stay >5 days

RESULTS:

• 2,559 deliveries | 90.8% delivered vaginally | 78.2% delivered vaginally in the mildly protracted group (4–6 hours) | 64.2% delivered vaginally after very protracted active phase (>6 hours)
• Composite maternal morbidity was higher with longer labor
  • Very protracted active phase (42.0%) vs normal active phase (22.6%)
    • Adjusted odds ratio (aOR) 2.15 (95% CI, 1.62 to 2.86)
  • Mildly protracted active phase (39.5%) vs normal active phase (22.6%)
    • aOR 2.18 (95% CI, 1.67 to 2.84)
• Composite neonatal morbidity was higher with longer labor
  • Very protracted active phase (19.8%) vs normal active phase (13.8%)
    • aOR 1.38 (95% CI, 0.98 to 1.96)
  • Mildly protracted active phase (19.4%) compared with normal active phase (13.8%)
    • aOR 1.44; (95% CI, 1.04 to 1.99)
• No statistical differences were found when comparing very protracted to mildly protracted active phase
• On further analysis, maternal composite was driven by maternal fever | Neonatal composite was driven by NICU admission
• Among women who underwent cesarean, there was no difference in primary or secondary outcomes based on rate of cervical change

CONCLUSION:

• In both mildly and very protracted labor vs normal active phase (<4 hours)
  • Odds of composite maternal morbidity were twice as high
  • Odds of composite neonatal morbidity were 1.5 times as high
• As there did not appear to be statistical difference between mild vs very protected phase, the authors conclude that

These findings support ACOG–SMFM recommendations to allow labor to continue for at least 6 hours after a woman has reached 6 cm before calling an arrest disorder and proceeding to cesarean delivery

Learn More – Primary Sources:

Maternal and Neonatal Morbidity After 4 and 6 Hours of Protracted Active Labor in Nulliparous Term Pregnancies

Related ObG Topics:

Length of Time Between 4 to 6 cm: Is There an Increased Risk for Adverse Outcomes?

Results from the SLiP Pregnancy Monitoring Trial: The Ongoing Partograph Wars

What is the Length of Latent Phase that Defines a ‘Failed Induction of Labor’?

Could New Labor Management Guidelines be Doing More Harm than Good?

Labor Induction and an Unripe Cervix: Does it Result in More C-sections?