Purpose: In this review, we provide researchers and practitioners with an overview of the physical activity and pregnancy literature to promote prenatal physical activity, improve measurement, further elucidate the role of activity in reducing maternal health complications, and inform future research. Method: We examined past and present physical activity and pregnancy studies and highlight key papers with a focus on maternal health outcomes to best inform physical activity promotion efforts. Results: We discuss: (a) historical overview of prenatal physical activity relative to the physical activity guidelines, how they have changed over time, and how evidence of the effect of prenatal activity on maternal/fetal health outcomes has affected clinical recommendations; (b) existing tools and challenges associated with measuring prenatal physical activity; (c) empirical evidence on multilevel determinants of prenatal activity to guide future intervention work; (d) empirical evidence of prenatal activity on adverse maternal outcomes (gestational diabetes mellitus, preeclampsia, excessive gestational weight gain) from observational and intervention studies; and (e) summary/recommendations for future research and practice. Conclusions: The physical activity and pregnancy literature has evolved over the past 50 years, and there is sufficient empirical evidence to support the promotion of moderate-to-vigorous prenatal physical activity for maternal health benefits. Future studies and interventions should be carefully designed, theoretically driven, and include validated and reliable activity measures. Researchers and practitioners should also consider the multifaceted determinants and outcomes of prenatal physical activity and intervene to promote physical activity before, during, and after pregnancy. (Contains 1 table and 1 figure.)