Objective: To identify how reliably CD4+ (helper) lymphocyte count and p24 antigenaemia can predict mother-to-infant transmission of human immunodeficiency virus type 1 (HIV-1).
Design: Prospective study.
Setting: University of Turin Center for Intravenous Drug Users (IVDU) and/or HIV-1 seropositive pregnant women.
Subjects: Twenty-nine infants born to asymptomatic seropositive women from November 1985 to June 1991.
Results: Seven children (24%) developed symptomatic infection, while 22 healthy seronegative children at the age of 18 months were considered uninfected. A CD4+ lymphocyte count persistently < 500/mm3 during pregnancy was associated significantly with the child's infection status with a relative risk (RR) of 11.4. (CI 1.58-82.05). A marked association (RR 13.6) (CI 1.93-95.72) was similarly detected between maternal antigenaemia and the risk of the child being infected. In a multivariate logistic analysis, crude and adjusted odds ratios (OR) of transmission were 27.0 (95% CI 2.5-291.2) and 35.6 (1.1-1159) for low CD4+ counts; 64 (3.2-1261) and 51.6 (2.5-1058) for p24 antigenaemia.
Conclusions: Asymptomatic HIV positive women with a CD4+ count below 500/mm3 or p24 antigenaemia are about ten times as likely to transmit the virus to their children. CD4+ lymphocytes decrease during pregnancy and a low CD4+ cell count early in pregnancy remains low up to delivery. Therefore knowledge that they have a low CD4+ lymphocyte count early in pregnancy may help women to decide whether or not to continue their pregnancy.