Background Malaria is a major problem which is serious in pregnancy. Pregnant women are more often exposed to malaria infection compared to non-pregnant women. The prevalence of malaria in pregnant women around the world is 10%–65%. In pregnancy malaria on the pregnant women are that it can cause anaemia, death, infant miscarriage, infant death, and low birth weight. The aim of this research was to describe the proportion of pregnant women with malaria and describe the influence of factors on high incidence areas and medium incidence areas in Nias district, Indonesia.

Methods This research used a cross-sectional design with primer data. A sample was taken from pregnant women who had not taken anti-malaria medication with the last month. 440 pregnant women were sampled, 220 pregnant women in a medium incidence area and 220 in high incidence area. The sample was taken by multistage random sampling. Analyses were conducted to describe the proportion and determinant factors in each area. Research variables were malaria, gravity, parity, stage of pregnancy age, mother's age, occupation, knowledge about malaria, usage of insect killers and closed outpits.

Results The proportion of pregnant women with malaria in the High Incidence Area (HIA) was 36.36% and Medium Incidence Area (MIA) 31.36% and HIA+MIA 33.86%. The proportion of pregnant women that had suffered a clinical symptom in the last month in HIA was 10.90% and in MIA 35.45%.

Conclusion Factors determining malaria prevalence in pregnant women in HIA and MIA are gravity, knowledge, usage of insect killer and closed outpits. The importance of treatment and how to protect from malaria can be achieved by having a standard book on malaria, blood examination during antenatal care and health promotion.