Increased susceptibility to malaria during the early postpartum period

Background Pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this increased risk ends with delivery, but the possible persistence of increased susceptibility during the puerperium has not been investigated. Methods From June 1 1990, to December 31, 1998, we monitored exposure to malaria, parasitemia, and morbidity among the residents of a village in gal in which the rate of transmission of malaria was In this population we analyzed 71 pregnancies in 38 women from the year before conception through one year after delivery. Results Among the 38 women, there were 58 episodes of clinical Plasmodium falciparum malaria during 61, 081 person-days of observation. The incidence of malaria was 20.2 episodes per 1000 person-months during the year preceding conception and 12.0 episodes per 1000 person-months during the period from 91 to 365 days after delivery. The incidence of episodes of malaria increased significantly during the second and third trimesters of pregnancy and reached a maximum of 75.1 episodes per 1000 person-months during the first 60 days after delivery. The adjusted relative risk of an episode of malaria was 4.1 (95 percent confidence interval, 1.8 to 9.5) during the first 60 days post partum, as compared with the year ceding pregnancy. The duration of fever during the episodes of malaria was longer and the prevalence and density of asymptomatic malarial parasitemia were significantly higher during pregnancy and the early postpartum period than during the other periods. Conclusions Among women who live in areas with high rates of transmission of malaria, the susceptibility to malaria is highest during the second and third trimesters of pregnancy and the early postpartum period. (N Engl J Med 2000; 343: 598-603.) (C) 2000, Massachusetts Medical Society.