Epidemiology of vertically transmitted HIV-1 infection in Switzerland: results of a nationwide prospective study. Swiss Neonatal HIV Study Group.

A nationwide study involving 286 children of human immunodeficiency virus (HIV)-infected mothers living in Switzerland has been performed with the participation of all paediatricians interested in HIV infection in the country. Of these children 201 could be followed up prospectively from birth up to a median age of 22 months. Prevalence of HIV infection in Swiss parturients was estimated at 0.1% and apparently remained stable from 1986 to 1989. Vertical transmission rate was estimated at 14%-20%. Variables of maternal or perinatal history were not associated with transmission rate. Transmission to pairs of siblings of the same mothers was discordant in 33% (6 of 18), with always the elder sibling being infected. Postneonatal mortality in infants of HIV-infected mothers followed up from birth was increased 15-fold over the general population with a very high incidence (2 in 100) of sudden infant death apparently unrelated to HIV infection.