Fetal gender and pregnancy outcome.

Objective: To assess the effect of fetal gender on pregnancy outcome.
Methods: Retrospective study of all singleton pregnancies at a tertiary hospital during 1995-2006.
Results: Of the 66,387 women studied, 34,367 (51.8%) delivered male and 32,020 (48.2%) delivered female neonates. The rate of preterm delivery (as early as 29 weeks) was higher for male fetuses and was attributed to an increased incidence of spontaneous preterm labor and preterm premature rupture of membranes. Women carrying male fetuses were at increased risk for operative vaginal delivery (OVD) for non-reassuring fetal heart rate, failed OVD and cesarean delivery. Female fetuses were more likely to experience fetal growth restriction (FGR).
Conclusion: Fetal gender is independently associated with adverse pregnancy outcome. Although the added risk is relatively small, further investigation of the mechanisms underlying this association may contribute to our understanding of the pathophysiology of pregnancy complications such as preterm delivery and FGR.