Risk for perinatal HIV-1 transmission according to maternal immunologic, virologic, and placental factors.

OBJECTIVE: To evaluate how maternal and obstetric factors interact to influence mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission. DESIGN: Prospective, observational cohort study of children born to HIV-infected women to determine child's HIV infection status. The analysis then compared peripartum maternal, placental, and obstetric variables between HIV-1 transmitter and nontransmitter women. SETTING: Two large maternity wards in Kinshasa, Zaire. PARTICIPANTS: Consecutive sample of 324 HIV-1-infected women at delivery, with 254 HIV-seronegative women followed up as control subjects. PRINCIPAL OUTCOME MEASURES: HIV infection status of children, to classify each woman as an HIV-1 transmitter or nontransmitter. RESULTS: The highest transmission risk (TR) was associated with maternal p24 antigenemia (TR, 71%; relative risk [RR], 3.0; 95% confidence interval [CI], 1.7 to 5.2) and maternal CD8+ lymphocyte counts of at least 1.80 x 10(9)/L (1800/microL) (TR, 50%; RR, 2.2; 95% CI, 1.2 to 4.2). Among women with CD8+ lymphocyte counts of less than 1.80 x 10(9)/L, CD4+ lymphocyte counts of less than 0.60 x 10(9)/L were a risk factor (TR, 29%; RR, 2.2; 95% CI, 1.2 to 4.2). In women with neither high CD8+ nor low CD4+ lymphocyte counts, placental membrane inflammation was associated with perinatal transmission (TR, 40%; RR, 4.2; 95% CI, 1.3 to 13.7). In women with neither p24 antigenemia, high CD8+ or low CD4+ lymphocyte counts, nor placental membrane inflammation, the transmission risk was only 7%. Additional correlates of transmission included maternal anemia and fever, but not maternal sexually transmitted diseases. CONCLUSIONS: Identifiable subgroups of HIV-1-infected women based on maternal and placental characteristics had between a 7% and 71% risk of perinatal HIV-1 transmission. Not only the overall rate of transmission but the impact of different risk factors for transmission appear to vary over the course of HIV infection.

Evidence from Zaire that breast-feeding by HIV-1-seropositive mothers is not a major route for perinatal HIV-1 transmission but does decrease morbidity.

Breast-feeding as a route of HIV-1 transmission during infancy but also as a protective measure against early childhood morbidity has been investigated prospectively in children born to HIV-1-seropositive mothers and control children born to age- and parity-matched HIV-1-seronegative women. The mothers of all study children had been enrolled antenatally at a maternity hospital in Kinshasa, Zaire, which served a relatively affluent group of women who sometimes chose not to breast-feed their infants. In 106 children born to HIV-1-seropositive women, the rate of HIV-1 transmission was 21% in 28 infants exclusively breast-fed, 19% in 68 infants both breast- and bottle-fed and 0% in 10 infants who were bottle-fed only (P = 0.35). In contrast, non-HIV-1-infected children of both HIV-1-seropositive and HIV-1-seronegative mothers who were exclusively breast-fed compared with uninfected children who were not exclusively breast-fed had significantly lower incidence rates of acute diarrhea, fever and lower respiratory tract infection. The lack of a dose-response effect between breast-feeding and perinatal HIV-1 transmission and the presence of a protective effect of breast-feeding against common causes of early childhood morbidity and mortality support the current World Health Organization recommendation that breast-feeding should continue to be promoted in all developing countries, including those with high HIV-1 prevalence rates in women of childbearing age.