Context.— It is unclear whether elective cesarean delivery may have a protective
effect against the transmission of human immunodeficiency virus 1 (HIV-1).
Objective.— To investigate whether mode of delivery has an impact on perinatal HIV-1
transmission in the presence of zidovudine prophylaxis.
Design.— A prospective cohort study.
Setting.— The 85 perinatal centers in the French Perinatal Cohort, from 1985 to
1996.
Patients.— A total of 2834 singleton children born to mothers with HIV-1 infection.
Main Outcome Measure.— Human immunodeficiency virus 1 infection of the infant.
Results.— No zidovudine was used in 1917 pregnancies and zidovudine prophylaxis
was used in 902 pregnancies. Cesarean deliveries were performed in 10.9% on
an emergent basis and in 8.3% electively, prior to labor or membrane rupture.
In 1917 mothers who did not receive zidovudine, of 1877 with information on
mode of delivery, 17.2% transmitted HIV-1 to their child. Risk factors statistically
significantly associated with transmission were maternal p24 antigenemia,
cervicovaginal infections during pregnancy, amniotic fluid color, and rupture
of membranes 4 hours or more before delivery. Mode of delivery was not related
to transmission. In 902 mothers receiving zidovudine, transmission was 6.4%
in 872 with information on mode of delivery, and elective cesarean delivery
(n=133) was associated with a lower transmission rate than emergent cesarean
or vaginal delivery (0.8%, 11.4%, and 6.6%, respectively; P=.002). In a multivariate analysis of all mother-child pairs, including
obstetrical risk factors, maternal p24 antigenemia, and zidovudine prophylaxis,
interaction between mode of delivery and zidovudine prophylaxis was significant
(P=.007). In the multivariate analysis of pregnancies
with zidovudine prophylaxis, factors related to transmission rate were maternal
p24 antigenemia, amniotic fluid color, and mode of delivery. Adjusted odds
ratios (95% confidence intervals) were 1.6 (0.7-3.6) for emergent cesarean
delivery and 0.2 (0.0-0.9) for elective cesarean delivery (P=.04) in comparison with vaginal delivery.
Conclusions.— We observed an interaction between zidovudine prophylaxis and elective
cesarean delivery in decreasing transmission of HIV-1 from mother to child.
This observation may have clinical implications for prevention.