Psychological aggression has been shown to have harmful effects on both partners, sometimes above and beyond the effects of physical aggression. However, very little is known about psychological aggression during the transition to parenthood. The transition to parenthood is a time where relationship satisfaction often declines and stress increases, which may put the couples at higher risk for psychological aggression. The purpose of this study was to examine if prenatal risk factors related to interpersonal style (specifically, emotional flooding and hostility) predict changes in psychological aggression from pregnancy to 2 years postpartum. Ninety eight couples took part in this study. The couples completed self‐report questionnaires during pregnancy, 1 year postpartum, and 2 years postpartum. Both partners were asked about perpetrating and experiencing psychological aggression in their current relationship. Two level Hierarchical Linear Models (HLMs) were used to examine longitudinal associations between hostility, flooding, and psychological aggression. For women, hostility during pregnancy was a significant longitudinal predictor of psychological aggression. For men, flooding was a significant longitudinal predictor of psychological aggression. For both men and women, relationship satisfaction partially mediated the relationship between flooding/hostility and psychological aggression, indicating that women's hostile attitudes and men's tendency to be flooded tend to erode relationship quality, leading to increases in psychological aggression. This may represent a classic demand‐withdraw dynamic in couples. The results indicate hostility for women and flooding for men are potential prenatal risk factors for future psychological aggression. Implications and future research directions are discussed. Aggr. Behav. 9999:1–16, 2014. © 2014 Wiley Periodicals, Inc.