Cardiovascular malformations: Changes in prevalence and birth status, 1972-1990

Through an ongoing hospital-based active malformation surveillance program, we identified cardiovascular malformations (CVMs) in 3.3 per 1,000 livebor n and stillborn infants, and fetuses from pregnancies terminated electively during a 15-year period. We excluded the children of mothers who had plann ed delivery elsewhere, but were transferred for care of anomalies that had been detected in prenatal screening, Birth status changed markedly during t he study with a significant increase in elective terminations of fetuses wi th a CVM from 0 to 22% (P < 0.01 based on a test for trend). The proportion of liveborn infants with CVMs decreased from 90% to 73% (P < 0.01); the fr equency of stillbirths did not change, During the study period, there was a significant increase in the prevalence of CVMs in all births (P < 0.01) an d elective terminations (P < 0.01), The increase in liveborn prevalence was not statistically significant (P = 0.08), Stillborn prevalence was unchang ed. The number of mothers having prenatal ultrasonography (P < 0.01 for tre nd) and amniocentesis (P < 0.01 for trend) increased steadily. There were s ignificant increases in the pro-portion of mothers having any ultrasound ex amination (P < 0.01 for trend), the number of initial ultrasound examinatio ns occurring in the second trimester (P < 0.01 for trend), and the proporti on of mothers having amniocentesis (P < 0.01 for trend), There was a signif icant increasing trend in the proportion of mothers who were 35 years and o lder (10% in 1972-1974, 26% in 1988-1990, P < 0.01), This hospital-based ac tive surveillance program suggests that more frequent elective terminations had a significant effect on overall birth prevalence of CVMs, This trend w ould not have been detected by most other surveillance systems which determ ine prevalence of common birth defects from birth certificates and other fo rms of administrative reporting, and exclude elective terminations of pregn ancy, Am. J, Med, Genet. 84:102-110, 1999, (C) 1999 Wiley-Liss, Inc.