Stephen Harper announced the new funds, for 2015 to 2020, at a Toronto-area primary school Thursday.
The commitment is slightly more than the $3.25 billion that a coalition of aid groups had been requesting, and was widely lauded by development organizations and international figures attending the summit Harper is hosting this week.
The money builds on Harper's five-year, $2.8-billion commitment to his so-called Muskoka Initiative, unveiled when Canada hosted the G8 summit in 2010.
Rosemary McCarney, a veteran Canadian aid worker who is one of the leaders of a 70-member coalition of aid groups, praised Harper for "a rolling, 10-year commitment, which is very rare in our world."
"We can actually produce real results when we've got time to get systems embedded in remote and rural communities," she added.
Harper said he planned to "persuade and cajole" other governments to follow Canada's lead and pony up more funds.
Dave Toycen, the head of World Vision Canada, said the commitment is significant because it will sustain momentum beyond 2015 on maternal and child health and keep it from being a flavour-of-the-month in the development world.
"I'm really encouraged. It's clear that the prime minister, the government is keeping their commitment," he said.
Stephen Brown, a political science professor who specializes in foreign aid, was highly critical of Harper's approach, though he said the funds are going to a worthy cause.
But with the government continuing to cut foreign-aid spending, this new commitment will only reduce what Canada can do in other areas, he said.
"We're focusing on symptoms and we're abandoning the underlying causes, which are poverty and inequality."
Brown also said the government excluded from the conferences anyone who might be critical of its policies.
"There aren't multiple voices at the table. The summit's a bit narcissistic; we're going to pat ourselves on the back; we're going to invite people who will tell us how great we are."
Harper has made helping young mothers and newborns in developing countries his signature aid priority.
He says the new funds will be focused on helping young children in the first month of life, who die in numbers that experts describe as alarming.
The prime minister is hosting a three-day meeting with experts from around the world, including philanthropist Melinda Gates, who gave the keynote speech at the summit's first full day.
Harper said there have been some successes, but more must be done.
"It will expand on our existing policies and up our game in three critical areas," Harper said of the new funds.
"This is good work. It is making a difference between life and death so this work must not stop."
Harper said expanded funding would go toward immunization, nutrition and birth and death registration.
"You can't manage what you can't measure," he said.
In her speech earlier Thursday, Gates lauded Harper for his "powerful advocacy on behalf of people in developing countries."
"Under your leadership, and with the support of many people in this room, Canada has earned a global reputation for driving the agenda when it comes to women and children," she said.
"The Muskoka Initiative rallied the entire world around saving mothers and their babies."
Gates also credited International Development Minister Christian Paradis with strengthening Canada's relationship with non-governmental organizations.
The comment appeared to be aimed at Harper's critics who say he is using the most basic motherhood issue to boost domestic support.
She said Canada deserves credit for funding organizations that have tried to eradicate polio, AIDS, tuberculosis and malaria.
Gates said spending money on the health of women and children pays broad economic dividends, and she made clear she has the heft to advocate for the less fortunate, on whatever side of the power corridor she chooses to walk.
"When I talk to health ministers from developing countries, they want to hear how we can reduce mortality," she said.
"When I talk to finance ministers, they want to hear how we can increase GDP. Well, let's make sure everybody knows that the answer is the same in both cases: invest in the health of women and children."
Earlier, Queen Rania of Jordan denounced the deaths of millions of mothers and newborns every year.
"These figures are more than a source of discontent; they are an outrage, an injustice and they have no place in our common humanity," said the 43-year-old monarch of the tiny Middle East desert kingdom.
"So thank you to Prime Minister Harper and the Canadian government for being discontented with the status quo."
The Aga Khan, the spiritual leader of the world's 15 million Shia Ismaili Muslims, also praised Harper for leadership on the issue, but said much more needs to be done.
"The truth is that our efforts have been insufficient and uneven," he said.
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