Objective: To estimate the perinatal HIV transmission rate and describe the natural history of infant HIV infection in a situation in which HIV status is known in more than 95% of delivering women.
Design: A cohort of HIV-exposed infants born between 7 July 1987 and 30 June 1990, whose mothers were identified by routine voluntary universal HIV testing, were followed using clinical and laboratory measures.
Setting: Grady Memorial Hospital, a major health-care site for individuals of lower socioeconomic status in Atlanta, Georgia, USA, with approximately 7000 deliveries per year.
Patients: HIV-exposed infants (n = 165), 98% of whom were African American.
Results: Annual maternal HIV seroprevalence increased from 0.58 to 0.86%. The annual proportion of HIV-positive women having a second delivery increased from 4.3 to 25%. Clinical outcome was known for 132 out of 165 infants (22 infected and 110 uninfected), the transmission rate was 17% (confidence interval, 11-24%). The rate declined to 11% by the third year of the study. Gestational growth, prematurity and mode of delivery were unrelated to infant outcome. There was a trend for intravenous drug use to be more common in mothers of infected infants (P = 0.08). After 35 months median follow-up of infected infants, eight out of 22 (36%) had an opportunistic infection (seven Pneumocystis carinii pneumonia); three out of 22 (14%) had lymphocytic interstitial pneumonia, and 10 out of 22 (45%) were asymptomatic or had only nonspecific symptoms. Cumulative mortality in infected infants was 9, 32 and 32% by 1, 2 and 3 years of age, respectively.
Conclusion: In this cohort of HIV-exposed infants, perinatal HIV transmission was 17% overall. Factors affecting the transmission rate and possible future changes in the rate require further study.