Canadian Prime Minister Justin Trudeau pledged $650 million this week for worldwide reproductive health services and sex education. His announcement came during International Women's Day, marked this year by strikes and rallies around the globe. The money will be doled out over the next three years.

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Trudeau's announcement comes after U.S. President Donald Trump's reinstatement of the "global gag rule," which bars foreign aid from going to NGOs that provide or discuss abortions. The Canadian contribution will help close the funding gap left by that decision.

Master Steve Rapport - flickr.com

So what's the global gag rule?

In 1984, President Ronald Reagan instituted the global gag rule at a United Nations conference in Mexico City. The rule stated that NGOs would have to certify that they do not "perform or actively promote abortion as a method of family planning" in order to receive U.S. aid money. In fact, under the rule providers are not even allowed to mention the word abortion to those women they were serving.

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In the years since, the rule has become a bit of a political football, getting punted back and forth as new administrations take hold. President Bill Clinton, a Democrat, immediately repealed it, while President George W. Bush, a Republican, reinstated it — only for another Democrat, President Barack Obama, to repeal it again.

What makes Trump's version so different? 

In the past, the only aid that was limited by the gag rule was U.S. funding toward family planning—$608 million in 2016. But under Trump's version of the rule, all U.S. aid for global health purposes will be impacted. That's $9.5 billion.

Access to safe abortion is already a huge problem in developing countries, with roughly 22,000 women dying each year around the globe due to unsafe abortions. Trump's executive order will likely cause that number rise; a 2008 World Bank report—issued right at the end of George W. Bush's second term — estimated the number of women who died at around 68,000.

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Have any other countries pledged money to fill the funding gap?

Yes. Norway has responded with $10 million and the Netherlands has set up an international safe abortion fund to help plug the gap, which over a dozen countries have indicated they will support. Whether that will be enough to make up for hundreds of millions of U.S. aid dollars remains to be seen.