MOTHER-TO-CHILD TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 -REPORT FROM THE NAIROBI STUDY

Mother-to-child transmission of human immunodeficiency virus type 1 (H IV-1) is a significant problem in countries with endemic HIV-1 infecti on. Between 1986 and 1991, 365 children of HIV-1-infected mothers and 363 control children were studied in Kenya. The overall risk of transm ission from mother to child, determined by serologic evidence of infec tion by age greater than or equal to 12 months and excess mortality in the HIV-1-exposed group, was 42.8% (range, 27.6%-62.2%). Marriage was the only maternal characteristic associated with transmission (odds r atio, 2.2; 95% confidence interval, 1.2-4.2; P < .05). Children who ex perienced growth failure were more likely to be infected. In 44% of ch ildren ultimately infected, the pattern of antibody response implied i ntrapartum or postnatal exposure to HIV-1. Of potential postnatal expo sures examined, duration of breast-feeding beyond age 15 months and th e mother being married were independently associated with increased ri sk of infection and seroconversion of children. The percentage of HIV infection attributable to breast-feeding greater than or equal to 15 m onths was 32%. The frequency of mother-to-child transmission of HIV-1 was high; a substantial proportion of infection occurred postnatally, possibly through breast-feeding.