Trends in congenital malformations, 1974-1999: effect of prenatal diagnosis and elective termination.

OBJECTIVE: To examine trends in congenital malformations, elective terminations for malformations and correlates for the decision to terminate a pregnancy with a malformation.
METHODS: All malformed liveborn and stillborn infants and elective terminations for malformations were identified in a large urban tertiary center and general hospital for the years 1974, 1979, 1984, 1989, 1994, and 1999. Nine hundred and fifty-four women with malformed infants, who had always planned to deliver at the hospital, were identified. Prenatal screening by ultrasonography or amniocentesis before 24 weeks of gestation, severity rating of the malformation, parity, marital status, race, level of education, insurance status, and pregnancy history were determined
RESULTS: In each of these 6 years, about 2% of newborn infants had a major malformation. The rate of prenatal screening by ultrasonography and amniocentesis before 24 weeks increased from 7% in the years 1974 and 1979 to 61% in the years 1984 and 1989 to 89% in the years 1994 and 1999. Elective termination increased from less than 1% in the years 1974 and 1979 to 18% to 20% in the years 1984, 1989, 1994, and 1999. Pregnancies with fatal and severe conditions were much more likely to be terminated electively than pregnancies with moderate or mild conditions (odds ratio 53.3; 95% confidence interval 22.7-124.7)
CONCLUSION: The introduction of routine prenatal screening and the subsequent increase in elective termination for malformed fetuses means that the inclusion of terminated pregnancies in malformation surveillance programs is necessary to study prevalence and risk factors in the epidemiology of malformations.