Knowledge about safe medication use during pregnancy is limited, yet about two of every three women take at least one prescription medication during pregnancy, furthermore, there is a lack of rigorous studies evaluating birth outcomes associated with in utero exposure to medications. The Medication Exposure in Pregnancy Risk Evaluation Program (MEPREP) is intended to provide a mechanism for collaborative pharmacoepidemiological research to address the safety of pharmaceutical product exposure during pregnancy, through the development of standardized data requirements and of the necessary data linkages of mother-infant pairs to conduct multi-site investigations. This presentation will describe the program, the types of data collected, and progress to date. The current MEPREP population includes female health plan members of 11 distinct health management entities within three research centres who have delivered an infant between January 1, 2001 and December 31, 2007, along with the administrative and birth certificate data on over one million children linked to mothers. There is information on all the medications those mothers took, as well as most of the outcomes of the babies. One of the benefits of this dataset is the information that could be investigated, such as birth weight, fetal growth, congenital anomalies, perinatal conditions, etc., against various demographics of the women in the dataset. The population size within the dataset suggests that various parameters could be studied with at least a modest degree of power.