Impact of fetal gender on the labor curve

Objective: We sought to estimate the association between fetal gender and first-stage labor curve at term.

Study design: Within a large, retrospective cohort study of consecutive, singleton term labor patients who delivered in the second stage, we compared the active phase of first-stage labor by fetal gender. The primary outcome was length of active stage 1. Interval-censored regression was used to estimate the effect of fetal gender on the duration of active first stage (4-10 cm) and was adjusted for relevant covariates.

Results: Of 2400 women, 2373 women had complete labor information and were available for this analysis. Male gender was associated with both a statistically significantly longer active first stage of labor (4.6 vs 4.0 hours; P = .002) and stratified analyses by parity and labor type.

Conclusion: Male fetuses are associated with longer active phase of the first stage of labor and, specifically, may need to be considered in the setting of arrest diagnoses.