Increase of birth weight following chloroquine chemoprophylaxis during the first pregnancy: results of a randomized trial in Cameroon.

A randomized trial was carried out from 1991 to 1993 among women attending an antenatal clinic in Ebolowa, Cameroon where malaria is hyperendemic and transmission occurs at a high level all year round. All pregnant women attending the clinic for their first prenatal visit between October 1991 and November 1992 were alternately assigned to chloroquine (CQ) or control (CT) groups. Chloroquine was given under observation at a weekly oral dose of 300 mg. At delivery, smears from maternal, cord, and placental blood were made and stained with Giemsa for parasites. An in vivo chloroquine sensitivity investigation was carried out on women attending the postnatal consultation to evaluate the level of chloroquine resistance in the target population. The efficacy of chloroquine was moderate in placental infection (39.2% infected in the CQ group versus 57.8% in the CT group: P = 0.05), probably because of a resistance to chloroquine estimated to be 10.9%. In the CQ group, the mean birth weight was significantly higher (P = 0.02) and the proportion of low birth weight newborns was lower (10.5% versus 27.7%; P = 0.02). A strong correlation between placental infection and birth weight was observed: the mean birth weight difference between infected and noninfected placentae was 359 g (P < 0.0001) and the proportion of low birth weight new born babies was 35.6% versus 5.9% (P = 0.0001). In Cameroon, in spite of a moderate resistance to chloroquine, this drug proved to be highly effective in increasing birth weight when administered to primigravidae. We therefore think such a prophylaxis should be recommended only to primigravidae in high transmission areas.