BACKGROUND AND PURPOSE:

• Offringa et al. (International Journal of Gynaecology and Obstetrics, 2022) evaluated the risk for spontaneous preterm birth (sPTB) following a second stage cesarean section in a previous pregnancy

METHODS:

• Retrospective cohort study (2003 to 2018) 
• Population
  • 2 consecutive births at a single hospital during the study period
  • First birth: Singleton livebirth at term (≥37 weeks of gestation)
  • Second birth: ≥16 weeks
• Exposures
  • Group A: vaginal delivery at first birth
  • Group B: cesarean section before the second stage of labor at first birth
  • Group C: cesarean section during the second stage of labor at first birth
• Study design
  • Multivariate analysis performed to account for confounding
    • BMI | smoking | Bacterial vaginosis | IVF pregnancy | Other risk factors associated with preterm birth     
• Primary outcome
  • sPTB in the second pregnancy (delivery <37 weeks)
• Secondary outcome
  • Preterm rupture of membranes in the second pregnancy
  • SPTB <32 weeks
  • Maternal morbidity
  • Neonatal morbidity

RESULTS:

• Group A: 7776 women | Group B: 1263 women | Group C: 143 women
• There was an association between sPTB in the second pregnancy if the first ended in second stage cesarean
  • Group C vs Group A: Adjusted odds ratio (aOR) 2.2 (95% CI, 1.2 to 4); P=0.010
  • Group C vs Group A+B: aOR 2.4 (95% CI, 1.2 to 4.8); P=0.01
• The rate of preterm rupture of membranes was also significantly higher in those with a prior second stage cesarean
  • Group A: 2%
  • Group B: 3%
  • Group C: 6% (vs A: P=0.009 | vs B: P=0.05)
  • Group C vs Group A+B: OR 3.0 (95% CI, 1.55 to 6.16); P<0.001
• No difference seen for the following
  • sPTB <32 weeks
  • Severe maternal morbidity
  • Severe neonatal morbidity

CONCLUSION:

• A prior second stage cesarean is associated with an increased risk of sPTB and premature rupture of membranes in subsequent pregnancy
• The authors state

In order to prevent the risk of preterm birth in a subsequent pregnancy, second stage cesarean section should be reconsidered as much as possible

Improving instrumental birth assistance skills and increasing attempts of instrumental assistance in the operating room could reduce second stage CS and thus preterm birth

Learn More – Primary Sources:

Second stage cesarean section and the risk of preterm birth in subsequent pregnancies

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