The head of the World Health Organisation on Wednesday criticised the US Supreme Court decision to overturn Roe v. Wade. calling the decision to no longer recognize a constitutional right to abortion “a setback” that would ultimately cost lives.

WHO Director-General Tedros Adhanom Ghebreyesus said during a media briefing that decades of scientific data prove that access to safe and legal abortion saves lives.

Also read: Roe v Wade: Hillary Clinton calls Justice Thomas ‘person of grievance‘

“The evidence is irrefutable,” Tedros said. “Restricting (abortion) drives women and girls toward unsafe abortions resulting in complications, even death.”

He said safe abortion should be understood as health care and warned that limiting its access would disproportionately hit women from the poorest and most marginalised communities.

“We hadn’t really expected this from the US,” Tedros said, adding that he was concerned the Supreme Court’s decision was a move “backwards.”

Also read: Why US drug store chains are rationing contraceptives

In recent years, the US has supported numerous maternal health care programs in developing countries, including access to reproductive health care.

“We had really hoped the US would lead on this issue,” Tedros said.

WHO’s chief scientist, Dr. Soumya Swaminathan, said the UN health agency’s position on abortion was based on decades of data from numerous countries.

Also read: US pharma retailers ration contraceptive pills after Roe v Wade overturned

“I know from own experience, working in India, that having access to safe abortion is a life-saving measure,” Swaminathan said. She said denying a woman access to abortion was “like denying someone a life-saving drug.”

She said bans on abortion would do little to reduce the number of procedures while people who undergo unsafe abortions are at risk of developing fatal blood infections.

Also read: How Silicon Valley responded to Roe v Wade overturning

“What these bans do… is it drives women into the hands of people who are there to exploit the situation, performing unsafe abortion and very often resulting in a huge amount of damage to their health and sometimes death,” Swaminathan said.

In recent years, the trend among countries has been to increase access to abortion, including regions where there was staunch opposition, like Latin America, she said.

“It’s unfortunate to see some countries going backward,” Swaminathan said, citing the US decision.

Also read: Instagram, Facebook remove abortion pill posts after Roe v Wade reversal

WHO chief Tedros said he feared many other countries might not understand the implications of the US Supreme Court ruling and could take similar measures to restrict abortions.

“The global impact is also a concern,” he said. “This is about the life of a mother,” he said.

“If safe abortion is illegal, then women will definitely resort to unsafe ways of doing it. And that means it could cost them their lives.”