The U.S. Supreme Court on Thursday blocked Louisiana from enforcing a law that women's groups said would leave only a single doctor legally allowed to perform abortions in the state.

By a 5-4 vote, the court said the restrictions must remain on hold while challengers appeal a lower court decision in favor of the law.

It was the Supreme Court's first significant action on the hot-button issue of abortion since President Donald Trump's nominee, Brett Kavanaugh, replaced Anthony Kennedy, who generally voted with the court's liberals to uphold abortion rights, NBC News reported.

The vote was not a ruling on the legal merits of the Louisiana restriction, but the decision to keep the law on hold signals that a majority of the justices have doubts about its constitutionality.