Protesters in Warsaw marched from the office of Ordo Iuris, a conservative group that has pushed for a full abortion ban, to the parliament building, which was surrounded by police officers in riot gear.
Large crowds also filled the streets in other major cities, including Krakow, Wroclaw, Szczecin and Lodz.
In parliament, Poland’s most powerful politician, ruling party leader Jaroslaw Kaczynski, lashed out at opposition legislators, accusing them of inciting people to protest during the pandemic.
“You are destroying Poland,” Mr Kaczynski told them. “You are exposing a lot of people to death, you are criminals.”
The nationwide strike and protests came amid a deepening stand-off between angry demonstrators and Poland’s deeply conservative government, which pushed for last Thursday’s court ruling and has vowed not to back down.
Daily protests since Poland’s constitutional court issued its decision have exposed deep divisions in a country long a bastion of conservative Catholicism and now undergoing rapid social transformation.
Anger over the ruling, which would deny legal abortions to women even in cases of fatal birth defects, has been directed at the Roman Catholic Church and ruling party leader Mr Kaczynski.
He said in the past that pregnancies involving even foetuses that are badly damaged and have no chance of survival outside the womb should “still end up in a birth, so that the child can be baptized, buried, have a name”.
On Sunday, women entered Polish churches on Sunday to disrupt Masses, confronted priests with obscenities and spray-painted church buildings.
Mr Kaczynski accused protesters of seeking “to destroy Poland” late on Tuesday and called on his party’s supporters to defend churches “at any cost”.
He spoke to a camera backed by Polish flags in an announcement that some critics compared to a notorious announcement of martial law in 1981 by communist leader Wojciech Jaruzelski to crack down on anti-regime protests.
Some saw Mr Kaczynski’s words as an incitement to violence.
On Sunday, members of some far-right groups and football fans surrounded churches to defend them, in some cases provoking skirmishes with protesters and police.
Interior Minister Mariusz Kaminski said 76 people have been detained in connection with the protests at churches and prosecutors are carrying out proceedings in 101 cases.
Polish President Andrzej Duda, who is in isolation after testing positive for Covid-19, said last week that he supported the court ruling.
His daughter Kinga Duda, appointed as an unpaid advisor to her father on social issues, said on Wednesday that she could not accept it.
Kinga Duda said that any woman carrying a foetus that could die within moments of birth should be allowed to decide what to do since she will be the one “to face the consequences of her decision for the rest of her life”.
