There are so many significant hematological changes occurring in pregnancy, erythrocyte sedimentation rate (ESR) is one of them. The objectives of this study were to determine the range of erythrocyte sedimentation rate values obtained in healthy pregnant women and to examine the effect of gestational age and hemoglobin concentration on erythrocyte sedimentation rate. Patients and methods: This is a quantitative analytic cross-sectional study conducted in several primary health centers in different places in Erbil-Iraq from April 1st 2015 to April 1st 2016. A convenience sample of (300) healthy pregnant women in the reproductive age groups (15-45 years) and in their first, second and third trimester were included. Erythrocyte sedimentation rate, hemoglobin concentration, and gestational age were estimated in all participants. Chi square and ANOVA analysis were used to determine the influence of hemoglobin concentration and gestational age on erythrocyte sedimentation rate.Results: For 300 pregnant women examined, the mean ESR value was 47.69 ± 25 mm/h and the range values obtained were 5-116 mm/h. Gestational age and hemoglobin concentration both significantly influenced erythrocyte sedimentation rate (P<0.001).There was a statistically significant difference between the mean ESR value in anemic and non-anemic pregnants (P = 0.003).There was a statistically significant increase in ESR in the course of pregnancy from 1st to 3rd trimester (P<0.001). Occupation shows a statistically significant association with ESR (P = 0.05), while no significant association was found between ESR and other socio-demographics.Conclusions: This study shows that erythrocyte sedimentation rate increases during pregnancy and that both gestational age and hemoglobin concentration significantly influence erythrocyte sedimentation rate. For the correct interpretation of ESR values obtained during pregnancy, gestational age and hemoglobin concentration must be taken into account.