Harper said the summit builds on the work Canada began at the Muskoka G8 meeting in 2010.
That meeting backed a five-year, multibillion-dollar program to improve the health of mothers and children in developing countries.
The Toronto meeting will bring together experts from governments, international organizations, charitable foundations and the private sector to measure progress to date and look at future directions.
It will look at ways to strengthen health systems and vital statistics systems and to build partnerships with the private sector to take advantage of innovation, the Prime Minister's Office said.
The Muskoka Initiative, as it is called, is forecast to save hundreds of thousands of children and mothers over its five-year span.
The PMO says progress is being made, and the number of women who die each year during pregnancy or childbirth has dropped to 287,000 in 2011 from 543,000 deaths in 1990.
"Saving the lives of mothers and children is not only a moral imperative, it is also the foundation for building prosperous communities for this generation and the next," Harper said in a statement.
Dave Toycen, president and CEO of World Vision, welcomed the announcement of the Toronto meeting.
"We've seen great progress in saving the lives of children and mothers through the efforts of the Muskoka Initiative and Canada's global leadership on the WHO Accountability Commission," he said.
"Yet, we know that 6.6 million children are still dying every year from preventable causes."
To help those children, health services need to reach farther and track results better, he said.
"That's why it's so important that Canada convene these leaders to come together for a final push to end preventable deaths."