Infections and other maternal factors as risk indicators for congenital malformations: a case-control study with paired serum samples.

An obstetric population of 48,000 individuals was prospectively followed up for evidence of possible teratogenic factors that might be associated with congenital malformations. Serum samples from 274 mothers of defective children and from paired controls were collected during early pregnancy and approximately one month after delivery and tested for antibodies against ten different viruses, Mycoplasma pneumoniae, and Toxoplasma. These data were supplemented with clinical information on infections, other diseases, drug intake, and other potentially teratogenic factors during pregnancy. Mothers of defective children had more seroconversions (fourfold or greater increase in titer) than the controls, 123 vs. 86. This difference was mainly due to an increase in herpes simplex viruses 1 and 2, cytomegalovirus, varicella-zoster virus, and Toxoplasma titers. In addition, the number of reported diseases during the pregnancy, the intake of drugs (especially analgesics and hormones), and the number of earlier abortions were greater in the mothers of the defective children than in the controls.