Effect of Labor Induction, Epidural Analgesia and Centimeters Dilated at Hospital Admission on Risk of Cesarean Delivery at First Childbirth

Background:  Nearly a third of all births in the US are by cesarean delivery (CD) and 60% of CDs are to first-time mothers.  Although there are efforts to reduce the CD rate in the US, risk factors are not well understood.  

Methods:  As part of a large-scale cohort study, we investigated risk factors for unplanned CD (n = 2,851) via logistic regression, controlling for confounding factors, including pre-pregnancy BMI, height, age and gestational weight gain.

Results:  35.6% were induced - which more than doubled risk of CD (odds ratio (OR = 2.3 (95% confidence interval (CI) = 2.0-2.8).  Epidural analgesia also increased women’s risk of CD and among women who were induced and received epidural analgesia, 36.0% had a CD, while among those who were not induced and did not receive epidural analgesia 8.1% did (OR = 15.2, 95% CI = 7.7-29.9). Centimeters dilated at hospital admission was also significantly associated with risk of CD.  More than half (52.1%) who were 0 centimeters dilated at hospital admission had CD, while among those who were dilated at least 5 centimeters, 11.4% did.  In logistic regression with induction, epidural use, and centimeters dilated, controlling for confounding factors, all 3 of these predictors remained significant (p < .01) and centimeters dilated was the most significant (p < .0001).

Conclusions:  Three treatment-related factors significantly and independently increase a woman’s risk of having an unplanned CD at first childbirth – hospital admission at less than 5 centimeters dilation, labor induction and use of epidural analgesia.