Trisomy after pregestational contact with communicable disease.

Six hundred nineteen mothers who had had household contact with rubella, infectious hepatitis, measles, mumps or varicella at a known time before or after their last menstrual periods were identified in a study in West Jerusalem, Israel. The mother's subsequently-born babies included four with Down's syndrome and one with trisomy 18. The mothers of these five children had been exposed to a communicable disease during the five months preceding pregnancy. The possibility that maternal pregestational contact with communicable disease might have contributed to autosomal trisomy in the official offspring is considered.