The demonstration in the capital violates pandemic restrictions which limit public gatherings to five people, with participants disregarding government appeals for people to stay home due to rocketing coronavirus infections.
Poland has hit new records for confirmed cases almost daily this week, including 21,600 confirmed cases reported on Friday.
Rallies are also being held in other Polish cities.
The national public prosecutor promised to file criminal charges against protest organisers for “causing an epidemiological threat”, a charge that carries a prison sentence of up to eight years.
Klementyna Suchanow, one of the key organisers with the Poland’s Women’s Strike initiative, said she and many others refused to be deterred by the virus or the authorities because they believe they are fighting for a fundamental right.
“This is about the freedom and dignity of people,” Ms Suchanow said. “The will of people to protest should be a lesson for anyone who wants to impose authoritarian ways.”
Security forces are out in large numbers, including military officers deployed by the government amid the recent street protests.
The past week of social upheaval followed an October 22 ruling by Poland’s constitutional court, which held that abortion in cases of severe foetal deformities was unconstitutional.
Poland already had one of Europe’s most restrictive laws. Forged by political and Catholic Church leaders in 1993, it allowed abortion only in the cases of foetal defects, risk to the woman’s health and pregnancies resulting from crimes — incest or rape.
The law has been often described as a compromise between those seeking liberal abortion regulations and the church, which favours a total ban. However, neither side has ever been satisfied with the 1993 law, and women’s groups demanding greater reproductive rights say it struck no balance at all.
Last week’s constitutional court ruling leaves only the woman’s health or pregnancy resulting from crimes as legal reasons for abortion.