Background: Nutritional iron deficiency (ID) is the most widespread nutritional deficiency disorder; IDA in pregnancy may have a serious effect on the health of both the mother and the baby. Anemia can increase maternal and infant morbidity and mortality. Objective: This study aimed at measuring the prevalence rate of anemia in pregnant women in the study population, and the adherence of pregnant women to iron supplementation, and identifying different factors affecting adherence to iron supplementation during pregnancy. Method: A cross sectional study was carried out in Gezert Mahros primary health care center, Dar Salama Abd Alla maternal and childhood health care center and Neda primary health care center. We included a sample of 400 pregnant women. The data were collected through personal interviews with the participants using a standardized questionnaire containing questions about socioeconomic status, obstetric history, and the use of health care services during pregnancy, exploring women's knowledge about anemia, adherence assessment, and factors affecting adherence. Results: The anemia prevalence rate was 44.75%. By pill counting adherence 25.5% of pregnant women were found to be adherent to iron supplements, there were significant associations between pill counting adherence and the family role to encouraging the woman to take medications, maternal education and maternal occupation. Conclusion: Family physicians should be aware of non-adherence problem and factors affecting adherence and try to improve adherence of pregnant women to iron supplement intake.