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.


METHODS
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.


CONCLUSIONS
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.
Division of Maternal-Fetal Medicine, Washington University in St. Louis School of Medicine, St. Louis, MO 63105, USA. cahilla@wustl.edu
Alison G
AG
Cahill
Kimberly A
KA
Roehl
Anthony O
AO
Odibo
Qiuhong
Q
Zhao
George A
GA
Macones
D000328:Adult; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007747:Labor Stage, First; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012737:Sex Factors; D055815:Young Adult