The relationship of the duration of ruptured membranes to vertical transmission of human immunodeficiency virus.

Objective: Intrapartum events may play a role in determining the likelihood of vertical transmission of human immunodeficiency virus-1. Timing and duration of rupture of membranes have been shown to modify transmission risk of other organisms but have not been examined for human immunodeficiency virus. This study was undertaken to assess the relationship between duration of rupture of membranes, maternal immune status, and transmission of human immunodeficiency virus.
Methods: The Mothers' and Infants' Cohort Study enrolled 207 human immunodeficiency virus-positive women and their infants at five study sites in Brooklyn and the Bronx, New York between January 1986 and January 1991. One hundred twenty-seven woman-infant sets for whom antepartum CD4+ levels were available, the infant's human immunodeficiency virus infection outcome was known, and the duration of ruptured membranes could be determined were included in this analysis.
Results: Thirty of the 127 evaluable infants (24%) were infected. Women with low CD4+ levels (< 20%) were significantly more likely to transmit the virus if rupture of membranes was > or = 4 hours (relative risk 4.53, 95% confidence interval 1.14 to 1.81, p = 0.02). The same association was not observed among women with higher CD4+ levels (relative risk 1.11, 95% confidence interval 0.52 to 2.69, p = 0.69). No association with the duration of labor or mode of delivery was seen.
Conclusions: In this urban North American cohort women with low CD4+ levels were significantly more likely to transmit human immunodeficiency virus to their offspring if the duration of rupture of membranes was > or = 4 hours.