An externally validated model to predict prolonged induction of labor
with an unfavorable cervix: a retrospective cohort study
Abstract
Objective: To develop and externally validate a prediction model to
calculate the likelihood of prolonged induction of labor (induction
start to delivery time >36 hours). Design: A retrospective
cohort study Setting: Academic centers in the United States Population:
Nulliparous women with singleton pregnancies and vertex presentation at
term who underwent induction of labor and had a vaginal delivery at a
single academic center. Methods: Analyses were limited to women with an
unfavorable cervix. A backward stepwise logistic regression analysis was
used to identify the factors associated with prolonged induction of
labor. The final model was validated using an external dataset of the
Consortium on Safe Labor after applying the same inclusion and exclusion
criteria. We developed a receiver observer characteristic curve with
area under the curve (AUC). Main outcomes of measures: Prolonged
induction of labor Results: Of 2,118 women, 364 (17%) had prolonged
induction of labor. Factors associated with prolonged induction of labor
included body mass index, hypertension, fetal conditions, and epidural.
Factors including younger maternal age, prelabor rupture of membranes,
and a more favorable simplified Bishop score were associated with a
decreased likelihood of prolonged induction of labor. In the external
validation cohort, 4,418 women were analyzed, of whom 188 (4%) had
prolonged induction of labor. The AUC of the final model was 0.76
(95%CI 0.73-0.80) for the external validation cohort. The online
calculator was created and is available at
https://medstarapps.org/obstetricriskcalculator. Conclusion: Our
externally validated model was efficient in predicting prolonged
induction of labor with an unfavorable cervix.