Both Bernie Sanders and Hillary Clinton have now pledged to change or repeal the Helms amendment, a longstanding US policy that prevents foreign aid from funding abortion — even if a woman has been raped or if her life is in danger.

The Huffington Post reports that Clinton says she would "fix" the Helms amendment, with an executive order clarifying that it allows exceptions for rape, incest, or life endangerment. The Sanders campaign went further, saying that Sanders would both fix the amendment himself and push Congress to repeal it entirely.

This is a big deal for a couple of reasons. Changing this policy could have a huge impact on women's health and safety abroad. But it's also a big deal because President Obama, who has called reproductive rights a "fundamental American value," hasn't done anything to change the policy during his administration — even though he has the power to do so without an act of Congress.

Current US policy makes things difficult for pregnant rape victims in conflict zones

The Helms amendment is currently interpreted as a blanket funding ban on abortion no matter the circumstances. Advocates say that has a chilling effect on the NGOs and medical providers who offer women's health care in developing countries.

Providers fear losing funding from the US, which is the world's largest donor to women's health programs. So some providers stop offering abortion services altogether, even if the US isn't directly funding those services.

The Huffington Post's Laura Bassett reported from Kenya on how the Helms amendment set back abortion rights in that country. Kenya has abysmally high rates of both sexual assault, which can lead to unwanted pregnancies, and maternal death, which can be caused by unsafe illegal abortion.

After 100,000 women started going to the hospital or dying every year from unsafe abortion, Kenya decided it had a crisis on its hands and legalized abortion in 2010 for health reasons, including mental health, rape, or incest. But, fearing censure from the US, Kenya repealed that change in 2013.

When the Islamic militant group Boko Haram kidnapped and raped hundreds of women and girls in order to create a new generation of fighters, most of those girls came back pregnant — but none of them had the option to safely end those pregnancies.

While abortion is illegal in Nigeria except to save a woman's life, Nigeria is also subject to a treaty that requires abortion access for rape or incest victims, or for women whose physical or mental health is at risk. NGOs and governments could have pressured Nigeria to live up to its obligations under that treaty. But they didn't, for fear of losing funding due to the Helms amendment.

Meanwhile, 18.5 million women have unsafe abortions every year in developing countries, and 47,000 women die from them worldwide.

The president could change this with the stroke of a pen

Right after he took office, Obama repealed the "global gag rule," which prohibits providers from even talking about abortion if they want to receive US funding. But he didn't do anything about the Helms amendment, a policy that leads some foreign health care providers to act almost as if the gag rule were still in place. He could have, though.

The Helms amendment leaves some room for interpretation, and the executive branch can choose how to interpret it. The actual text of the law says aid to foreign countries can't pay for "the performance of abortions as a method of family planning," but it doesn't define "family planning."

Another federal ban on abortion funding, the Hyde amendment, applies to women in the US — but it makes exceptions for rape, incest, and life endangerment. Advocates say there's no reason the Helms amendment shouldn't include the same exceptions for women abroad, and that the text of the law actually allows this.

But it's never been interpreted that way, even by pro-choice presidents like Obama. It's not clear why that is, but fear of backlash from abortion opponents — including retaliatory cuts to all international family planning funding from Republicans in Congress — could be a factor. Both Helms and Hyde have been around since shortly after Roe v. Wade legalized abortion in 1973, and their bans on "taxpayer-funded abortion" are deeply important to the pro-life movement.

If the next president is a Democrat, though, that will change if the candidates keep their promises. Both Sanders and Clinton have said they will push Congress to repeal the Hyde amendment entirely. On the Helms amendment, both candidates now say they will at least use their executive power to clarify that Helms should have the same exceptions for rape, incest, or life endangerment as Hyde. And if the candidates went further than that on Helms, they could let US aid cover abortions for health crisis situations like the Zika virus.