To quantify health service costs of intimate partner violence (IPV) during pregnancy and postpartum; and to compare health service costs between women who reported IPV, versus women who did not report IPV. This was a cohort study using linked data for a publicly funded Australian tertiary hospital maternity service. Participants included all women accessing antenatal services between August 2016 and August 2018. Routinely collected IPV data were linked to women’s admitted, non-admitted, emergency department, perinatal, and costing data from 6 months prior to reporting IPV through to 12 months post-birth. Of the 9889 women receiving maternity care, 280 (2.9%) reported some form of IPV with 72 (24.8%) referred to support. Women who reported IPV generated higher mean total costs than women not reporting IPV ($12,772 vs $10,166, respectively). Between-group differences were significant after adjusting for demographic and clinical factors (cost ratio 1.24, 95% CI: 1.15–1.34). There were no significant differences in mean total costs for babies where IPV was and was not reported ($4971 vs $5340, respectively). IPV is costly for health services. However, greater research is needed to comprehensively estimate the long-term health service costs associated with IPV. Furthermore, the limitations associated with routinely collected IPV data suggest that standardised screening practices and innovative data linkage and modelling approaches are required to collect data that truly represents the burden and costs associated with IPV.