BACKGROUND AND PURPOSE:

• There is literature suggesting longer interpregnancy intervals bring multiparous labor curves more in line with nuliparas
• Longer interbirth intervals may be associated with cesarean section
• Mason et al. (American Journal of Perinatology, 2018) compared labor curves between mulitiparas women with varying interpregnancy intervals

METHODS:

• Retrospective cohort study
  • Multiparous
  • 13 to 60 years
  • Term vaginal delivery in the studied pregnancy
  • Known interbirth interval
• Subjects were grouped based on interbirth intervals between the studied pregnancy and most recent birth (months)
  • Group 1: 0 to 59
  • Group 2: 60 to 119
  • Group 3: ≥120
• Interbirth interval: Defined as time between the delivery of the studied pregnancy and delivery of the most recent prior pregnancy
• Labor curve slopes and intercepts as well as length of second stage were compared

RESULTS:

• 250 charts were reviewed
  • Data extracted, and curves developed
• Groups did not differ significantly in demographic data, including BMI, parity or GA
• Faster progression to full dilation in group 3 vs group 2 with the following dilation rates (p = 0.038)
  • Group 1: 0.57 cm/h
  • Group 2: 0.52 cm/h
  • Group 3; 0.78 cm/h
• Rate of dilation was comparable between groups (p = 0.38)
• With Increased interbirth interval, median duration of second stage increased (p = 0.003)
  • Additional 15-25 minutes

CONCLUSION:

• Longer interval between births is not associated with slower active phase of labor
• While statistically significant, the slight increase in median duration of second stage from 15 to 25 minutes unlikely to be clinically significant
• Authors conclude that increased cesarean section rates seen in previous studies looking at birth or pregnancy intervals may not be due to labor progress but rather other factors

Learn More – Primary Sources:

Labor Curves in Multiparous Women Related to Interbirth Intervals

Related ObG Topics:

Does Maternal Age Modify the Risk Associated with Short Interpregnancy Interval?

Interpregnancy Interval and Adverse Perinatal Outcomes 

Conceiving After Pregnancy Loss – Is Waiting Beneficial?  

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