Abortion is wrapped up in politics in many nations including the U.S. But one in four pregnancies ends in abortion, making it a global health issue.

Abortion is one of the most common medical procedures globally.

It is grist for a raging political debate in the United States, nearly half a century after the highest court in the country ruled that women have the right to choose whether or not to end a pregnancy.

But abortion is far more than a political issue framed in ethical, religious or moral terms. It is also a matter of public health, for society and individual women.

The Guttmacher Institute, set up to study reproductive health, estimates that a quarter of all pregnancies globally are ended by abortion.

Abortion is constantly in the news, and in some countries it causes more political debates than any other single issue.

In the United States, abortion rights are being attacked by the administration of President Donald Trump and in conservative-led states such as Alabama and Georgia. Ireland, meanwhile, shocked the world and many of its own residents when voters chose to repeal one of the world’s most restrictive bans on abortion in 2018.

Abortion bans across much of Africa are being challenged in courts, even as religious campaigners use social media and billboards to depict abortion as a sin.

In centuries past, the Vatican defined pregnancy and human life as beginning when the fetus “quickened,” or started to move around in a way that the mother could feel. The same went for non-Catholic countries, including Britain and its colonies, until the 1800s. It wasn’t until modern medicine pinpointed the moment of egg meeting sperm that the idea of life at conception became common.

Healthcare need

But doctors around the world, and large majorities of voters in countries where abortion is legal, see embryos and fetuses as part of the woman’s body, not separate persons, at least until some stage in the pregnancy. And to them, abortion is above all a medical procedure.

“Safe, legal abortion is a necessary component of women’s health care,” the American College of Obstetricians and Gynecologists (ACOG), which represents women’s health specialists, says in its position statement. “Access to safe pregnancy termination options remains of vital importance.”

“It is a basic healthcare need for millions of women, girls and others who can become pregnant,” the human rights group Amnesty International says.

Women can need abortions for a variety of reasons, ACOG says. “They include, but are not limited to, contraceptive failure, barriers to contraceptive use and access, rape, incest, intimate partner violence, fetal anomalies and exposure to teratogenic medications,” it says. Teratogenic medications are drugs that can severely damage a developing fetus.

Other reasons include heart and kidney conditions, life-threatening high blood pressure and the rupture of the placenta — the organ that links a woman and the fetus. These conditions may be “so severe that an abortion is the only measure to preserve a woman’s health or save her life,” ACOG says.

Sometimes abortions are performed because the fetus has abnormalities. These can range from genetic conditions to hydrocephalus, a condition that can leave a developing fetus without any normal brain tissue. Such abnormalities might not be diagnosed until late in a pregnancy.

Abortion as political tool

Abortions can be done surgically, using a variety of methods, or medically, using drugs to stop the pregnancy and induce labor to expel the fetus or embryo.

When done by medical professionals in a clean setting and using the correct equipment, the World Health Organization and ACOG say the procedure is safer than pregnancy. Women are more likely to suffer complications or die during childbirth than they are during or after an abortion.

The earlier an abortion is done, the safer it is.

Dr. Jen Gunter, an obstetrician who has worked in both Canada and the United States, said she has had to perform very late-term abortions for medical reasons when a woman knew her baby would die at or soon after birth but decided to take it to term, anyway.

“The pregnant person thought they could make it to their due date, but they just can’t take it anymore. Or maybe their blood pressure is sneaking up and the idea of risking their life for a non-viable pregnancy is not what they want or their doctors recommend,” Gunter wrote on her blog.

Amnesty, the World Health Organization, ACOG, the American Medical Association and many other groups say laws that limit or outlaw abortion hurt women and do little to stop abortion from happening.

“Let’s be clear, if you are truly ‘pro-life’ you’d agree with these procedures because they save women. Not in an abstract way, but sometimes it is in a ‘this-infection-is-killing-you-and-we-need-to-help-you-right-now’ kind of way,” Gunter wrote.

“The one thing I’ve learned from my experience is that efforts to stop abortion after 20 weeks are nothing about life or compassion or good medicine. It is simply wielding the misery of women (and those who love them) as a political tool.”

Challenging Roe v. Wade

In 1973, an important U.S. Supreme Court decision called Roe v. Wade established a woman’s right to abortion, based on her right to privacy. Amnesty International agrees that the matter is personal.

“Human rights law clearly spells out that decisions about your body are yours alone — this is what is known as bodily autonomy,” the group said. “Forcing someone to carry on an unwanted pregnancy, or forcing them to seek out an unsafe abortion, is a violation of their human rights, including the rights to privacy and bodily autonomy.”

But conservatives across the United States are challenging this concept. U.S. states where abortion opponents dominate legislatures and governor’s offices have passed a variety of laws designed to challenge Roe v. Wade.

They include laws limiting how late in pregnancy an abortion may be performed; laws that establish strict medical requirements for abortion clinics that make it difficult or impossible for them to operate; laws that cut funding for organizations that provide or mention abortion; and laws that require doctors to tell patients that abortion is terminating the life of a human being.

ACOG, Planned Parenthood and other groups say these laws are not based on accurate medical need or practice.

The gag rule

The impact of U.S. policies can extend beyond the United States. Soon after he took office in 2017, Trump re-instituted a policy known as the Mexico City policy. First instituted by former President Ronald Reagan in 1984, it forbids federal funding for organizations providing abortions.

Washington has flip-flopped on this policy ever since. Democratic presidents — Bill Clinton and Barack Obama — have rescinded it. Republicans — George W. Bush and Trump — put it back into place. Trump’s administration has taken it further, forbidding U.S. federal funding to any organization that provides or refers women to abortion service — even if they don’t use federal funds for those services.

The policy, also called “the gag rule,” forces groups to give up all U.S. funding if they want to keep abortion in the mix of services they provide or if they want to support other groups that do.

But research shows the policy does not reduce the number of abortions and even makes them more common because people find it harder to get contraceptive care and counseling.

In a study published in June, Nina Brooks and colleagues from Stanford University in California found a 40% increase in abortions among women in 26 African countries in years when the gag rule was in place, compared to years when it was not.

They compared abortion rates globally during the Clinton, Bush and Obama administrations. “Our findings suggest how a U.S. policy that aims to restrict federal funding for abortion services can lead unintentionally to more — and probably riskier — abortions in poor countries,” they wrote in a report published in the Lancet medical journal.

This is in no small part because the United States is the biggest source of aid for medical and health services. When U.S. aid money disappears, organizations struggle to provide even basic health care, including birth control but also other health services such as HIV/AIDS prevention and primary care services.

Unsafe abortions

Women do not stop seeking abortions just because they are difficult or illegal to get, the international group Medecins Sans Frontières/Doctors Without Borders, says. “When a woman or girl is determined to end her pregnancy she will do so, regardless of the safety and legality of the procedure,” the group said.

“The history of unsafe abortion is marked by dangerous methods — including the use of sharp sticks inserted through the vagina and cervix into the uterus; ingestion of toxic substances such as bleach; herbal preparations inserted into the vagina; infliction of trauma, such as hitting the abdomen or falling.” Most methods don’t end the pregnancy, but injure or kill the woman.

The WHO studied abortions around the world between 2010 and 2014. “Around 25 million unsafe abortions were estimated to have taken place worldwide each year, almost all in developing countries,” the WHO concluded.

questions to consider:

1. Why is abortion often considered medically necessary?
2. What effects can laws restricting abortion have?
3. Why do some people oppose a woman’s right to have an abortion?

Maggie Fox has been reporting on health and science for more than 20 years and is currently a consulting editor to Medscape and WebMD and a consultant on health and science news. She has covered conflict, politics and other international events from London, Hong Kong and Beirut. She has covered the cloning of Dolly the sheep, Ebola epidemics, stem cell technology, vaccine controversies and other stories for Reuters, CNN, National Journal and NBC News. She lives in Washington, DC.