Intermittent Preventive Treatment in pregnancy (IPTp), with sulfadoxinepyrimethamine
(SP) is effective in reducing the adverse effects of malaria in pregnancy
but is not currently recommended in HIV-infected women taking cotrimoxazole (CTX)
prophylaxis. We investigated whether CTX given daily to pregnant HIV-infected women
prevents placental parasitemia. Based on prior trials, we set a threshold of <10%
placental malaria as an indication of adequate placental malaria prevention. Using an
observational study design, between 2008 and 2009, we collected demographic details,
history of CTX or SP use during pregnancy, peripheral blood smears and placental
biopsies from 375 HIV-infected women presenting for delivery at two district hospitals in
an area of high malaria transmission in western Kenya. The prevalence of placental
parasitemia among women who took CTX only was 6.1% (95% confidence interval (CI)
= 3.3-10.2%), compared to 10.2% (95% CI=3.4-22.2%) among women who took IPTp-
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SP, or 11.1 (95% CI=1.4-34.7) among those who took neither. The prevalence of
placental parasitemia among women who received CTX early in pregnancy (< 27 weeks
prior to delivery) was 6.9% (95% CI=3.0-13.1%) compared to 8.5% (95% CI=4.1-15.0)
among those who began taking CTX later in pregnancy. HIV- infected women who took
CTX had placental parasitemia prevalence below our defined threshold, supporting the
current WHO guidelines for malaria prevention in this sub-population.