Prediction of Duration of Active Labor in Nulliparous Women at Term

ABSTRACT

We have assessed the independent predictors of duration of active labor in nulliparous women at term. Using a cohort of 1067 nulliparae in spontaneous labor at > 37.0 weeks with singleton fetuses in vertex presentation, multivariate analysis was used to identify independent predictors of duration of active labor. Duration of active labor was 4.1 ± 2.4 hours. Stepwise linear regression selected 10 independent predictors of duration of active labor: gestational age at delivery (p < 0.001), race (p = 0.014), obstetric risk factors (p = 0.022), amniotomy (p < 0.001), fundal height (p = 0.005), cervical dilation on admission (p < 0.001), frequency of contractions (p < 0.001), station of presenting part (p < 0.001), oxytocin (p < 0.001), and epidural use (p < 0.001). A prediction formula incorporating the 10 predictors accounted for 51% of the total variance of the observed duration of active labor. Ten variables are independent predictors of duration of active labor; when incorporated in a prediction formula they account for > 50% of the variability of duration of labor in nulliparous women.

KEYWORDS

Active labor - nulliparous - partogram - curve of labor - prolonged labor

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