This prospective, population-based, cohort study analyzed 6346 singleton pregnancies in Sweden during the years 1992 to 2001 in which the infant had a congenital heart defect. The prevalence of cardiovascular defects in the study population, totaling 770,355 infants, was 9.1 per 1000 births. Cases with known chromosomal abnormalities or preexisting maternal diabetes were excluded. An isolated cardiovascular defect was present in 84% of infants, and in 22%, it was severe.
Case mothers did not differ substantially from control subjects with regard to age, parity, or smoking in early pregnancy. Obesity was more frequent in the case group; the crude odds ratio for having a body mass index of 25 kg/m2 or higher was 1.08 (95% confidence interval, 1.02–1.13). Cesarean delivery occurred more often in the case group, especially in cases with severe cardiac defects. The risk of instrumental delivery also was increased, but only when all cardiac defects were considered. In term infants, labor induction was significantly more frequent in the case group (odds ratio [OR], 1.12; 1.02–1.22), and the risk of preterm delivery was increased 2- to 3-fold. Infants with cardiac defects—especially severe ones—had lower birth weights than expected and were significantly more likely to be small for gestational age (OR, 2.46; 1.98–3.05). Those with milder defects, however, were likelier to be large-for-gestational-age infants (OR, 1.45; 1.28–1.64). Severe cardiac defects occurred in 26% of preterm infants compared with 21% of term infants (P < .001). Fetal distress, meconium aspiration, and low Apgar scores all were significantly more frequent in infants with cardiac defects. The incidence of preeclampsia was higher in case pregnancies (OR, 1.21; 1.06–1.37), but the incidence of stillbirth was the same in cases and control subjects.
In this large-scale, population-based study, several obstetric and neonatal complications were more frequent when a fetal heart defect was present. A search for congenital cardiac defects is appropriate in neonates who had complicated pregnancies.