Male fetuses are associated with increased risk for cesarean delivery in Malaysian nulliparae.

The association between fetal sex and outcome of pregnancy and labor has been well documented in western populations. However, no studies in Malaysia or other developing countries have examined the effect of fetal sex on such outcomes.The main objective of this study was to determine the influence of fetal sex on the outcome of labor at term in a cohort of Malaysian nulliparae.A retrospective observational study was designed using data from 4644 Malaysian nulliparae who gave birth consecutively to singleton male babies at Hospital Sultanah Aminah, Johor Bahru, after normal full-term pregnancies.The results of this study indicate that mothers giving birth to male infants have a greater risk of requiring cesarean delivery because male babies are heavier and have statistically significantly greater head circumference (P < .001). These findings concur with those obtained in western populations and suggest that the differences in outcome observed are biological, not dictated by race, ethnicity, or environmental conditions. Such information could help in the antenatal assessment of Malaysian patients and stimulate more comprehensive studies of the mechanisms involved in this sex-based difference in outcomes. Reasons for such differences are proposed.