Table 1.

Demographic and obstetric characteristics of the study cohort

Singletons (n = 805)Twins (n = 54)P
Maternal age, ya28.3 ± 5.929.3 ± 5.5NSf
Caucasian ethnicity, %82.087.0NS
Smokerb, %25.133.3NS
Gestational age at delivery, wksa39.0 ± 2.635.0 ± 3.0<0.0001
Birth weight, females, kga3.32 ± 0.592.09 ± 0.58<0.0001
Birth weight, males, kg3.31 ± 0.602.43 ± 0.65<0.0001
Placental weight, g587 ± 124862 ± 228<0.0001
Caesarean sectionc, %10.942.6<0.0001
Delivery following labord, %89.456.6NS
Labor duration, ha,e6.86 ± 4.35.38 ± 2.9NS
Prelabor rupture of membranes, %19.122.6NS
Induction of labor, %26.443.40.01
APH, %8.53.8NS
Antenatal steroids administered, %2.7520.8<0.0001
Preterm birth, %7.267.9<0.0001
IUGR, %3.024.1<0.0001

Abbreviation: NS, not significant.

  • aMean ± SD.

  • bSmoking defined as one or more cigarettes per day.

  • cIncludes both elective and in-labor sections.

  • dAll deliveries excluding elective Caesarean-section deliveries.

  • eStage I and II of labor combined.

  • fP > 0.05 by the Mann–Whitney U test for group median comparisons or Fisher's exact test for categorical variables.