Risk factors in congenital heart disease.

Risk factors were studied in 801 children with congenital heart disease (CHD) coming from 105,374 consecutive births of known outcome. The incidence of CHD was 7.60%. Diagnosis was performed in 66.5% of the cases during the perinatal period. Two-hundred-fifty seven of the cases also had at least one non-cardiac malformation (multiply malformed). Ninety-two cardiac infants (11.47%) had recognized chromosomal and non-chromosomal syndromes. The most frequent noncardiac malformations were renal, digestive and limb anomalies. For each case a control was studied. The following features were screened: sex ratio, parity and previous pregnancies, parental age, residency, education, ethnic origin, length, head circumference and weight at birth, genetic and environmental factors. Odds ratio values were calculated for the risk factors. Weight, length and head circumference at birth of cardiac infants were less than those of controls. The weight of placenta was also lower than in controls. The pregnancy with CHD was more often complicated by hydramnios and threatened abortions, except in infants with isolated CHD. Oliogoamnios was more frequent in pregnancies producing multiply malformed infants and those with recognized syndromes with CHD. One out of four children with CHD had an extracardiac malformation, which is ten times the rate of incidence of malformation in our population. The incidence of CHD in first degree relatives of these infants was 3.0%. These first degree relatives also had more non-cardiac malformations than did those of the controls.