BACKGROUND malaria during pregnancy is a major public health problem in Africa. It can have serious consequences for mother, fetus and newborn. It is associated with high maternal and infant mortality rate. The purpose of our study was to determine the prevalence of plasmodium infection in pregnant women, describe their clinical signs and potential complications, analyze associated factors, and propose preventive measures. METHODS we conducted a cross-sectional study at the Issaka Gazobi Maternity Ward (MIG), Niamey, from 1 June to 30 November 2017. Diagnosis was based on microscopic examination. RESULTS two hundred and forty-nine (249) women were included in this study. The prevalence of plasmodium infection was 36.5% (IC95%; [30.6; 42.9]). Mean parasite density was 177 P/μl (SD: 121; [40; 800]). All infections were due to P. falciparum. Seventy-three point six percent (67/91) of infected women were asymptomatic. Only 26.4% (24/91) of them had uncomplicated malaria; 9.6% (6/91) had miscarriage; 38.4% of newborns were low birthweight; 26.51% (66/249) developed congenital malaria. Mortality rate was 1.1% (1/ 91). Intermittent preventive treatment (IPT) significantly protected patients against gestational malaria (p=0.01). CONCLUSIONS in Niger, P. falciparum infection very commonly affects pregnant women. It is most often asymptomatic but it can lead to uncomplicated or even severe malaria. Main consequences include abortion, low birth weight, intrauterine growth retardation, congenital malaria and maternal death. IPT and the use of long-lasting insecticide-treated mosquito nets (LLINs) can prevent infection.