Spontaneous abortions in sibship of children with congenital malformation or malignant disease.

Parents of 751 children affected by cancer/leukemia, congenital heart disease, strawberry nevus or mental retardation have been investigated with respect to their reproductive history and their exposure to risk factors for spontaneous abortion. Differences between the four groups were established for the number of children in the sibship, the proportion of multigravidae and the spontaneous abortion rate among these women. The greatest differences were observed in the two groups of malformed children compared with the other two groups, being as marked in those with a severe malformation (heart defect) as in those with a benign one (strawberry nevus). Taking known risk factors for spontaneous abortion into account did not explain the observed differences. An etiological hypothesis is put forward which takes account of the high proportion of quantitative abnormalities of the karyotype associated with congenital heart disease and spontaneous abortion.