[Labor, method of delivery and maternofetal transmission of HIV]

Within a prospective study of the course of HIV-infection in women, 80 HIV-infected women without AIDS were delivered of 80 children between 1985 and September 1992. The median of the age of gestation was 38 weeks. Until 1988 Caesarean section was chosen as mode of delivery (45 women). Later when the mode of delivery appeared to have no influence on the frequency of maternofetal HIV transmission, vaginal delivery was preferred (35 women). None of the infants was breastfed. Three infants --delivered vaginally--died within the first 6 months of life before their infection status could be determined. Seventy-seven children could be observed for 18 months or longer regularly every three months. 10 of the 77 children were found to be HIV- infected by serological, virological and clinical criteria. Taking into account the mode of delivery, of 32 children who were delivered vaginally or by emergency Caesarean section 8 were found to be HIV-infected. None of 26 children delivered by elective Caesarean section after an uneventful pregnancy is infected. In 19 women Caesarean section was performed within 2 hours after onset of labour or after episodes of preterm labour which required hospital admission for treatment. Two children of these women are infected. No differences of CD4+ cell counts and p24 antigenaemia could be determined between the mothers of the three groups. The risk of fetal HIV infection was increased by preterm labour (p < 0.01) and the mode of delivery (p < 0.01). A correlation between loss of CD4 cells in the mother and increased risk of infection for the child is seen in children born spontaneously or delivered by emergency Caesarean section (p < 0.001). No correlation was found between the length of labour at delivery, the time of the rupture of membranes before birth as well as of the parity and the risk of fetal infection in that group. These findings point to labour as an important factor which increases the risk of maternofetal transmission of HIV. The onset of labour is accompanied by dramatic immunological alterations as a sudden increase of chemotactics and inflammatory cytokines at the maternofetal interface. The accumulation and stimulation of maternal immune cells will--if these cells are carriers of HIV--result in production and release of infectious HIV. This virus may accumulate in the maternofetal interface or gain access to the amniotic cavity. Since amniotic fluid is swallowed by the fetus, the largest potential port of entry for HIV in the fetus are the fetal lungs and the gastrointestinal tract. For the prevention of maternofetal transmission of HIV delivery before onset of labour or alternatively the protection of the fetus during parturition by means of potent antiviral compounds can be considered.