TIMING OF MATERNAL-INFANT HIV TRANSMISSION - ASSOCIATIONS BETWEEN INTRAPARTUM FACTORS AND EARLY POLYMERASE CHAIN-REACTION RESULTS

Objective: To investigate the hypothesis that labour and delivery even ts, perinatal characteristics, and maternal factors are only associate d with intrapartum HIV transmission, and not with intrauterine HIV tra nsmission. Methods: In the New York City Perinatal HIV Transmission Co llaborative Study 276 infants of HIV-infected women were followed pros pectively and had results of early polymerase chain reaction (PCR) tes ts available. Among infected children, intrauterine infection was pres umed if HIV DNA was detected by PCR in samples collected from children aged less than or equal to 3 days, and intrapartum infection was pres umed if HIV DNA was not detected in these early samples. The proportio n of infants with presumed intrauterine and intrapartum infections wer e compared by selected intrapartum, perinatal and maternal characteris tics.Results: Presumed intrapartum infection was found in 7% of infant s delivered by Cesarean section and, among infants delivered vaginally , those with longer duration of membrane rupture (> 4 h) were signific antly more likely to have presumed intrapartum HIV infection (22%) tha n those with shorter duration (9%; P = 0.02). There were no difference s in presumed intrauterine HIV infection by mode of delivery or longer duration of membrane rupture. infants born preterm and small for gest ational age had significantly higher risks of presumed intrapartum inf ection, but only those who were small for gestational age had higher r isks of intrauterine infection. Conclusion: Our results support the no tion that selected intrapartum conditions, long duration of membrane r upture prior to delivery in particular, are independent risk factors f or maternal-infant transmission, and suggest that preterm infants may be especially vulnerable to intrapartum HIV exposure.