The authors use a mixed-methods approach to investigate how the integration of electronic health records between ambulatory and hospital practices affected physician productivity and birth outcomes at a large health network. Physicians and staff were interviewed during a five-year staged integration of electronic health records, and a direct measure of physician productivity, relative value units, was analyzed concurrently with several measures of birth outcomes. The regression analyses show an 11% reduction in total productivity following the installation of the new system at primary-care sites. The qualitative findings indicate the reduction is attributable to the additional time physicians and staff needed to learn new processes, adopt work practice changes, and develop coordination. Nevertheless, users value the additional integration, especially as information flows back to the ambulatory practices from the hospital. This is supported by increases in treatment intensity over time and a 37% reduction in the severity of adverse birth events.