Male predominance in fetal distress during labor

OBJECTIVE: The purpose of this study was to assess the association between fetal sex and the occurrence of fetal distress during labor. STUDY DESIGN: This was a prospective cohort study that incorporated data about 423,033 singleton pregnancies from the national perinatal database for secondary obstetric care in The Netherlands. All singleton pregnancies on record that were delivered under the responsibility of obstetricians in The Netherlands between January 1, 1990, and December 31, 1994, were analyzed. Data about fetal sex, gestational age at delivery, birth weight, fetal distress during labor, mode of delivery, signs of asphyxia at birth, and perinatal death were collected. The associations between sex and the occurrence of operative delivery for fetal distress, low 5-minute Apgar score (score, 0-3), and perinatal death were evaluated by logistic regression analysis. RESULTS: Male fetuses are at increased risk for fetal distress during labor, for low Apgar scores, and for perinatal death. After adjustment for fetal birth weight and gestational age at delivery, the odds ratios were 1.48, 1.27, and 1.27, respectively. All three associations were highly statistically significant (P < .0001). CONCLUSION: Male fetuses are at increased risk during labor and delivery.