Reducing Mother-to-Infant Transmission of HIV — The Door Remains Open

A substantial proportion of perinatally acquired infections with the human immunodeficiency virus type 1 (HIV-1) occur at or near delivery, which suggests that obstetrical factors may have an important influence on transmission. We evaluated the relation of such factors and other variables to the perinatal transmission of HIV-1. The Women and Infants Transmission Study is a prospective, observational study of HIV-1-infected women who were enrolled during pregnancy and followed with their infants for three years after delivery. We studied obstetrical, clinical, immunologic, and virologic data on 525 women who delivered live singleton infants whose HIV-1-infection status was known as of August 31, 1994. Among mothers with membranes that ruptured more than four hours before delivery, the rate of transmission of HIV-1 to the infants was 25 percent, as compared with 14 percent among mothers with membranes that ruptured four hours or less before delivery. In a multivariate analysis, the presence of ruptured membranes for more than four hours nearly doubled the risk of transmission (odds ratio, 1.82; 95 percent confidence interval, 1.10 to 3.00; P = 0.02), regardless of the mode of delivery. The other maternal factors independently associated with transmission were illicit-drug use during pregnancy (odds ratio, 1.90; 95 percent confidence interval, 1.14 to 3.16; P = 0.01), low antenatal CD4+ lymphocyte count (<29 percent of total lymphocytes) (odds ratio, 2.82; 1.67 to 4.76; P<0.001), and birth weight <2500 g (odds ratio, 1.86; 1.03 to 3.34; P = 0.04). The risk of transmission of HIV-1 from mother to infant increases when the fetal membranes rupture more than four hours before delivery.

To assess health care providers' identification of human immunodeficiency virus (HIV)-exposed infants, to ascertain the prevalence of transplacental or oral zidovudine treatment among infants exposed to HIV, and to estimate the impact of zidovudine use on perinatal transmission in rural and urban North Carolina. Survey of North Carolina newborns tested for HIV infection in 1993 and 1994 compared with the number of anonymous HIV-positive childbearing women. North Carolina hospitals, public health clinics, and private physicians' offices. Rates of identification of HIV-exposed infants and of perinatal HIV-1 transmission, determined by HIV culture and polymerase chain reaction testing in the infants. The proportion of HIV-exposed children in North Carolina who were identified and tested increased from 60% in 1993 to 82% for all of 1994, and to more than 90% for the last quarter of 1994. The HIV-exposed infants born in rural counties were more likely to be recognized than those born in urban counties (P<.001). In 1994, most infants were evaluated relatively early in life: 39% by 1 week of age, 63% by 6 weeks, and 76% by 3 months. Among infants with recognized HIV exposure, transmission decreased significantly between 1993 and 1994, from 21% to 8.5%, respectively (P=.009). After the announcement of the results of the AIDS Clinical Trials Group Protocol 076, zidovudine was given to 75% of HIV-positive women who delivered infants in North Carolina. Only 5.7% of infants who received any zidovudine became infected, compared with 18.9% of infants who received no zidovudine (P=.007). Health care providers in North Carolina are identifying most of the state's HIV-seropositive pregnant women, treating them with zidovudine, and testing their infants soon after birth for HIV infection. The use of zidovudine in pregnant women and their infants has reduced perinatal HIV transmission in the state.