A US federal judge has temporarily blocked Missouri from enforcing a law banning nearly all abortions in the state after eight weeks of pregnancy.
The law was set to take effect on Wednesday.
It would ban abortions after eight weeks except in cases of medical emergency.
US District Judge Howard Sachs said it was not to be enforced, "pending litigation or further order of the court".
The decision to block the law's enforcement followed a legal challenge by Planned Parenthood and the American Civil Liberties Union. They sued Missouri last month, arguing that the law was unconstitutional and went against the Supreme Court's landmark 1973 Roe v Wade ruling, which legalised abortion nationwide.
A number of US states have introduced or proposed restrictive abortion regulations this year in an effort to challenge the ruling.
"While federal courts should generally be very cautious before delaying the effect of State laws, the sense of caution may be mitigated when the legislation seems designed, as here, as a protest against Supreme Court decisions," Mr Sachs wrote in his opinion on Tuesday.
A portion of the legislation prohibiting abortions based solely on race, sex or a diagnosis indicating the potential for Down syndrome was permitted to take effect.
Planned Parenthood said it would continue fighting to oppose that section of the law, too. "Every reason to have an abortion is a valid reason," Dr Colleen McNicholas, a chief medical officer with the organisation, said.
Attorneys for the state can now appeal against the ruling.
A spokesman for Missouri Attorney General Eric Schmitt said his office was reviewing the ruling before deciding what steps to take next.
What does the legislation say?
The law, dubbed Missouri Stands With The Unborn, would outlaw performing an abortion in nearly all cases.
Exemptions would be made for medical emergencies, but not pregnancies caused by rape or incest.
Doctors who performed abortions more than eight weeks into pregnancy would face five to 15 years in prison.
A woman who had an abortion would not be held criminally liable.
Republican Governor Mike Parson said it would allow Missouri to become "one of the strongest pro-life states in the country".
What is the background?
Abortion is one of the most divisive political issues in the US.
Missouri already has some of the nation's most restrictive regulations, with just one clinic in the state currently performing abortions.
Why is this happening now?
The Missouri bill was approved amid a nationwide push for new restrictions by opponents of abortions.
They have been emboldened by the addition of two conservative justices nominated by President Donald Trump, Neil Gorsuch and Brett Kavanaugh, who give the nine-member court a conservative majority.
Their aim, they say, is for the landmark 1973 Roe v Wade ruling to be undermined or overturned completely.