A Polish law limiting abortion to cases of rape, incest and when the mother's health or life is at risk was expected to go into effect Wednesday following an October court decision deeming abortions due to fetal defects illegal.
The court's decision set off protests across the mostly Roman Catholic country.
More protests were expected as the law goes into effect.
"See you in front of the Constitutional Tribunal today at 6:30 p.m.," the Women's Strike protest group, which organized many of the October protests, said on Facebook, according to Bloomberg News.
Opponents of the ruling allege the conservative Law and Justice (PiS) Party, which took power in 2015, influenced the court. The party denies the charge.
"No law-abiding government should respect this ruling," Borys Budka, leader of Poland's largest opposition party, the centrist Civic Platform, told reporters, according to Reuters.
Polish President Andrzej Duda said he supports the decision.
"I have said it many times, and I have never concealed it, that abortion for so-called eugenic reasons should not be allowed in Poland. I believed and believe that every child has a right to life," he said in an interview last October with Dziennik Gazeta Prawna.
Legal abortions have reportedly been declining in Poland, as some doctors are refusing to perform the procedure based on religious grounds, Reuters reported.