Tiffany was 17 weeks pregnant when her water broke while she walked to her car. The fetus wasn’t viable. Her OB-GYN team recommended an abortion—the standard of care, given the high risk of infection and death associated with her condition. While she considered her options, her blood stopped clotting properly—a possibly deadly complication. Doctors intubated her and rushed her to the ICU for a prolonged stay, where she had an emergency abortion. Without access to abortion, Tiffany would have died.
Tiffany, whose name we have changed, is an extreme example. In conversations around abortion rights, such extreme examples often come up as to why abortion is health care. And it’s true: Abortion can be an acutely lifesaving tool.
But carrying a fetus is inherently risky, even in normal pregnancies. The risk that something will go drastically wrong for the mother in pregnancy, or that there will be harmful lifelong health consequences, is unavoidable: Fundamental evolutionary forces have etched these risks into our genes. If you talk to five pregnant people in the USA, statistically one of them will experience a potentially serious complication, like high blood pressure or gestational diabetes.
Many of us are willing to take our chances, with the support of medical care, for the joy of childbirth. But if laws erase the choice to have an abortion, pregnant people will be legally required to put their health, and even lives, at risk. Biology makes sure of that.
The reason is simple: Sometimes what is good for the embryo is not good for the mother. Embryos extract resources from their mothers to improve their own health, which can at times come at the expense of maternal health. From the perspective of the embryo, the benefits of this “selfish” evolutionary strategy outweigh the corresponding costs—the chance of harm or death to the mother. Biologists have a term for this: “parent-offspring conflict.”
Embryos and mothers play a high-stakes game of tug-of-war, according to David Haig, a biologist at Harvard University: If all goes according to plan, the rope is steady. (Or steady enough—many pregnancies involve mild health problems.) But a small slip can send the rope flying. A genetic switch, preexisting condition, environmental stressor, or other complex factors can tip a pregnancy from safe to risky, the embryo increasing the flow of blood, the nutrients it contains, or otherwise enhancing its access to resources at the expense of the mother. This inevitable biological tug-of-war can cause the most common and dangerous pregnancy complications: high blood pressure, diabetes, and severe bleeding.
First, embryos can boost blood flow by remodeling the mother’s blood vessels, causing her blood pressure to spike. One in 13 pregnant women in the USA develop high blood pressure. (Research into these numbers tends to focus on women, but it applies to anyone who gets pregnant). This causes 7 to 8 percent of pregnancy-related deaths in the USA. But even for women who survive, high blood pressure during pregnancy doubles the risk of dying young from heart disease, and triples the risk of dying young from Alzheimer’s.
Second, embryos make the mother’s blood glucose levels skyrocket by releasing a powerful hormone, causing gestational diabetes in 1 of 7 US pregnancies. Half of women with gestational diabetes will develop Type 2 diabetes within 20 years, shortening their lifespan by eight to nine years on average.
Third, embryos directly access the maternal bloodstream by extending tendrils of a highly invasive placenta deep into the mother’s body. At birth, the placenta leaves a freely bleeding wound (which cannot be stanched due to embryonic remodeling of the mother’s blood vessels). As a result, severe bleeding at birth causes 11 percent of maternal deaths in the USA.
For some pregnancy complications, doctors and parents must choose between the mother’s health and the embryo’s health. For example, 1 in 25 pregnant women in the U.S. develop preeclampsia, a potentially life-threatening disease that causes high blood pressure and organ damage. When embryos cause preeclampsia, the only cure is to deliver the baby as soon as the baby is viable—or, if the risk to the mother is deemed great enough, to abort the baby.
Pregnancy is even riskier for women who face racial disparities in treatment, cannot access good health care, or have other health conditions (including COVID). Black and Indigenous mothers are two to four times more likely to die from pregnancy-related causes than white mothers. Women living in the South have a higher risk of death and poor maternal outcomes. Pregnant women diagnosed with COVID are more than three times more likely to die than nonpregnant women, and they have a significantly higher rate of miscarriage, stillbirth, and preterm deliveries. By banning abortions, we would enshrine in law serious discrepancies in risk based on race, region, and health.
We choose to avoid risky activities all the time out of concern for our own health. We eat less sugar, drink less alcohol, decline to go downhill skiing. Or maybe we indulge in those things, because we have weighed the risks and opted to take them. It is up to us, in consultation with our doctors. For someone who does not wish to be a parent, the health risks of pregnancy—which are far greater than those for everyday activities—may not be worth it.
If we ban abortion, we are forcing people to embrace serious physical risks that last beyond the nine months of pregnancy. Pregnancy risks are fundamental, written into our genes and our evolutionary history, and they are not going away anytime soon. While adoption can theoretically erase the burden of unwanted parenthood, we cannot erase the burden of unwanted, lifelong health risks from pregnancy. And unlike pregnancy, abortion has no long-term negative consequences on mental and physical health; in fact, abortion is significantly safer than childbirth. Access to this medical service preserves the right to protect one’s health, both immediately and into the future.