Domestic violence especially from intimate partner is the most common type of violence against women that has many psychological, social and economic adverse effects. Domestic violence in pregnancy causes serious problems for the infant and mother. Considering the importance of this matter, the present study investigated the frequency and intensity of intimate partner violence against pregnant women. In this cross-sectional study, two hundred and ninety inpatient mothers in post-delivery sections in educational hospitals were assessed using Iranian version of “Conflict Tactics Scale (CTS2)” after establishing the validity and reliability of this scale. 92.4%, 6.9% and 0.7% of women experienced very mild, mild and moderate intimate partner violence during their pregnancy. Verbal violence was rated as 40.9% and 0.7%, emotional violence as 81.1% and 1.7%, physical violence as 93.1% and 0.3% and sexual violence as 95.2% and 0.3%, as very mild and severe, respectively. Findings showed that there was a significant correlation between the violence against pregnant women and their neonates’ low birth weight. There was not a significant relationship between education of men and violence against their wives (P= 0.614 (. This research shows that many pregnant women experience the very mild forms of violence. The rate of neonates’ low birth weight has a significant relationship with the intimate partner’s violence against Iranian pregnant women. These findings showed the importance of this problem and the necessity of considering preventive strategies for that.