In the past decade, “big push” global health initiatives financed by international donors have aimed to rapidly reach ambitious health targets in low-income countries. The health system impacts of these efforts are infrequently assessed. Saving Mothers, Giving Life is a global public-private partnership that aims to reduce maternal mortality dramatically in one year in eight districts in Uganda and Zambia. We evaluated the first six to twelve months of the program’s implementation, its ownership by national ministries of health, and its effects on health systems. The project’s impact on maternal mortality is not reported here. We found that the Saving Mothers, Giving Life initiative delivered a large “dose” of intervention quickly by capitalizing on existing US international health assistance platforms, such as the President’s Emergency Plan for AIDS Relief. Early benefits to the broader health system included greater policy attention to maternal and child health, new health care infrastructure, and new models for collaborating with the private sector and communities. However, the rapid pace, external design, and lack of a long-term financing plan hindered integration into the health system and local ownership. Sustaining and scaling up early gains of similar big push initiatives requires longer-term commitments and a clear plan for transition to national control.