To examine the association between maternal intimate partner violence (IPV) victimization and unplanned pregnancy.Mothers of the Pacific Islands Families (PIF) Study cohort of Pacific infants born in Auckland, New Zealand during 2000 were interviewed when the children were 6 weeks old. A total of 1088 mothers cohabiting in married or de-facto partnerships were questioned about IPV and whether their pregnancy had been planned.Women identified as victims of physical violence were more likely to report an unplanned pregnancy than those who were not victims (68.7% vs 55.1%, odds ratio [OR] 1.78; 95% confidence interval [CI], 1.32–2.40). The adjusted odds remained statistically significant (OR 1.52; 95% CI, 1.01–2.26).The findings of this study suggest an association between IPV and unplanned pregnancy in the Pacific birth cohort.