The US Supreme Court is wrong to disregard evidence on the harm of banning abortion

Abortion could soon cease to be legal across the United States, according to a leaked draft of a US Supreme Court opinion, published by news outlet Politico on 2 May. The court’s chief justice, John Roberts, confirmed that the 98-page document is authentic, but not necessarily final. If the draft does represent the court’s final position, it will fly in the face of an overwhelming body of evidence from economists and reproductive- and public-health researchers who point to the dire, immediate and unequal impact this ruling will have on hundreds of thousands of people.

The draft, written by justice Samuel Alito on behalf of the majority of the nine-member court, declares a stunning end to the precedent set by a decision in the 1973 case Roe v. Wade, in which the court ruled that abortion rights were protected by the US Constitution. Mississippi’s state government is arguing against that landmark decision in its case against the state’s sole licensed abortion clinic, Jackson Women’s Health Organization.

The Mississippi legislature was emboldened by the latest composition of the Supreme Court when the court agreed to hear this case last year. Former US president Donald Trump shifted the balance when he appointed three justices, giving it a six-to-three conservative majority. All six have said in the past that they disagree with abortion precedents in US law. Notably, justice Amy Coney Barrett vowed in 2006 to end “the barbaric legacy of Roe v. Wade”. This was before she replaced the late justice Ruth Bader Ginsburg, who had fought to protect abortion rights.

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Should the 50-year precedent end, some 25 US states are poised to outlaw most abortions. Some of them have ‘trigger bans’ that go into effect as soon as Roe is overturned, and others have been moving towards prohibition through laws restricting the procedure.

Caitlin Myers, an economist at Middlebury College in Vermont, estimates that abortion bans in these 25 states will close so many clinics that roughly 18 million women of child-bearing age will end up more than 200 miles (322 kilometres) from an abortion provider (see ‘If Roe is overturned’). The Supreme Court might deviate from the leaked draft in its final decision, which is due to be published in the next two months. Even so, analysts expect the ruling to curtail abortion significantly, putting the United States out of line with an overall global trend towards abortion liberalization. Last year, for example, Argentina legalized the procedure, recognizing the public-health consequences of prohibition. Some 32 other countries have expanded abortion access in the past 25 years.

Moving in the opposite direction runs contrary to 50 years of research from around the world showing that abortion access is a crucial component of health care and is important for women’s equal participation in society. After the Supreme Court agreed to hear Mississippi’s case last year, Nature covered some of this evidence, submitted to the court by US scientific societies and more than 800 US researchers in public health, reproductive health, social sciences and economics, to the court in advance of the case’s hearing in December.

Empirical evidence

Some outcomes of outlawing abortion can be predicted by what’s known. Researchers expect overall infant and maternal health to decline in the United States in the wake of abortion bans, because more unintended pregnancies will be brought to term. Unintended pregnancies are associated with an increased risk of health problems for babies¹, and often for mothers², for several reasons — including reduced prenatal care.

Maternal health is also expected to decline overall. One straightforward reason is that the risks of dying from pregnancy-related causes are much greater than the risks of dying because of a legal abortion. A predicted rise in maternal mortality among Black women in the United States is particularly distressing, because the rate is already unacceptably high. In one study³, sociologist Amanda Stevenson at the University of Colorado Boulder modelled a hypothetical situation in which abortions are banned throughout the United States, and found that the lifetime risk of dying from pregnancy-related causes for non-Hispanic Black women would rise from 1 in 1,300 to 1 in 1,000.

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One claim made by abortion opponents in this case is that abortions no longer benefit women and even cause them harm, but dozens of studies contradict this. In just one, health economist Sarah Miller at the University of Michigan in Ann Arbor and her colleagues assessed around 560 women of comparable age and financial standing who sought abortions⁴. They found that, five years after pregnancy, women who were denied the procedure had experienced a substantial increase in debt, bankruptcies, evictions and other dire financial events — whereas the financial standing of women who had received an abortion had remained stable or improved. A primary reason that women give for wanting an abortion is an inability to afford to raise the child, and this study suggests that they understand their own situations.

Abortion bans will extract an unequal toll on society. Some 75% of women who choose to have abortions are in a low income bracket and nearly 60% already have children, according to one court brief submitted ahead of the December hearing and signed by more than 150 economists. Travelling across state lines to receive care will be particularly difficult for people who do not have the funds for flights or the ability to take time off work, or who struggle to find childcare.

Unfortunately, some of the justices seem to be disregarding these data. At the December hearing, Julie Rikelman, a lawyer at the non-profit Center for Reproductive Rights, headquartered in New York City, brought up studies presented in the economists’ brief; Roberts interrupted her and suggested “putting that data aside”. In the leaked draft opinion, Alito also elides a body of research on abortion policy, writing that it’s “hard for anyone — and in particular for a court — to assess” the effect of the right to abortion on women’s lives.

Such an attitude suggests that the justices see research as secondary to the question of whether the US Constitution should protect abortion. But the outcome of this ruling isn’t an academic puzzle. The Supreme Court needs to accept that the consensus of research, knowledge and scholarship — the evidence on which societies must base their laws — shows how real lives hang in the balance. Already, the United States claims the highest rate of maternal and infant mortality among wealthy nations. Should the court overturn Roe v. Wade, these grim statistics will only get worse.