The plaintiffs, known as the Alliance for Hippocratic Medicine, had argued that federal approval for the commonly used drug should be withdrawn.

The court struck down the nationwide guarantee, known as Roe v Wade, in 2022. Since then, 21 states have moved to restrict abortion earlier in pregnancy than the standard it set. Seventeen of those have barred the procedure at six weeks or earlier.

Medication abortion – using pills sent by mail – has quickly become an effective workaround to those bans.

The two-drug regimen was approved for use up to 10 weeks of pregnancy by the Food and Drug Administration (FDA) in 2000. A patient is first given mifepristone to induce an abortion and then misoprostol to empty the uterus.

Since 2016, the FDA has eased access to the drug and has allowed doctors to hold virtual appointments with patients and for prescriptions to be sent by mail.

Throughout two decades of use, the FDA, the American College of Obstetrics and Gynaecologists (ACOG) and other mainstream medical organisations have maintained that both mifepristone and misoprostol are safe for use.

US studies say medication abortion is about 95% effective in ending pregnancy and requires further medical follow-up less than 1% of the time.