Effects of Plasmodium vivax malaria in pregnancy

Background Plasmodium vivax is more common than P falciparum as a cause of malaria in many parts of the tropics outside Africa. P falciparum infection has harmful effects in pregnancy, but the effects of P vivax have not been characterised. We investigated the effects of P vivax infection during pre gnancy. Methods Since 1986, pregnant Karen women living in camps for displaced peop le on the western border of Thailand have been encouraged to attend antenat al clinics. Karen women were screened for malaria and anaemia at each week of pregnancy until delivery, and pregnancy outcome recorded. We compared th e effects of P vivax infection on anaemia and pregnancy outcome with those of P falciparum and no malaria infection in the first pregnancy recorded at the antenatal clinics. Findings There were 634 first episodes of pure P vivax malaria in 9956 wome n. P vivax malaria was more common in primigravidae than in multigravidae a nd was associated with mild anaemia and an increased risk of low birthweigh t (odds ratio 1.64 [95% CI 1.29-2.08], p<0.001). The birthweight was a mean of 107 g (95% CI 61-154) lower in women with P vivax infection than in uni nfected women, By contrast with P falciparum malaria, the decrease in birth weight was greater in multigravidae. P vivax malaria was not associated wit h miscarriage, stillbirth, or with a shortened duration of pregnancy. Interpretation P vivax malaria during pregnancy is associated with maternal anaemia and low birthweight, The effects of P vivax infection are less str iking than those of P falciparum infection, but antimalarial prophylaxis ag ainst P vivax in pregnancy may be justified.