Significance of cardiac defects in the developing fetus: a study of spontaneous abortuses.

We investigated the impact of heart defects on the developing human fetus by examining 412 hearts from consecutive spontaneous abortuses. In each case, the cardiac morphology was correlated with the autopsy findings and the karyotype (unavailable in 115 hearts not successfully cultured). Of the 412 hearts, 10 (2.4%) contained structural defects (six ventricular septal defects, one atrial septal defect with ventricular septal defect, and one each coarctation, atrioventricular septal defect, and tetralogy of Fallot). Only one of 10 had major extracardiac malformations. Of the 277 fetuses with normal karyotype, three (1.1%) had heart defects. Of the 20 fetuses with abnormal karyotype, four (20%) had heart defects. In the remaining three fetuses with heart defects, the karyotype was not obtained. Thus (1) 57% of spontaneous abortuses with congenital heart defects contained major chromosomal abnormalities, (2) the spectrum of heart defects among spontaneous abortuses was similar to that among liveborns, and (3) since the prevalence of heart defects among fetuses without other major abnormalities was similar to that among liveborns, heart defects alone may not jeopardize the survival of a developing fetus.