(CNN)Thousands of people marched in cities across Poland on Friday in demonstrations against plans to tighten the country's already restrictive abortion laws.
Protesters in Warsaw, many dressed in black, gathered outside parliament before marching through the capital to the headquarters of the ruling right-wing Law and Jusice (PiS) party, which is attempting to enact a staunchly anti-abortion bill for the second time in less than two years.
Poland is home to the toughest abortion laws in Europe. The procedure is only legal in three cases: if the pregnancy is the result of rape or incest, or if it endangers the life of the mother, or if the fetus is damaged. It is this third reason -- the most commonly cited -- that is the target of the latest proposals.
In 2016, urged on by Catholic groups, PiS lawmakers attempted to impose a total ban on abortion. But the law, which threatened to imprison women seeking the procedure, and any doctor who performed it, was scrapped after tens of thousands of people took to the streets in protest.
The same women's groups that rallied then were back out in force on Friday, protesting as lawmakers debated the revised bill entitled "Stop Abortion."
Crowds in Warsaw were scattered with placards reading: "Girl Power," "My body, my choice," and "#CzarnyPiątek" -- the hashtag for the movement: "Black Friday." Organizers with the Polish Women's Strike group estimated that some 55,000 people attended protests in the capital.
Over 200 nongovernmental organizations signed a public appeal to Polish lawmakers to reject the bill that they say "will place women's health and lives at risk and violate Poland's international human rights obligations."
"If adopted, this legislation will further limit the already restricted grounds on which women can lawfully access abortion in Poland," the letter read.
The Council of Europe's human rights commissioner Nils Muiznieks issued a similar warning to Warsaw on Friday.
Lawmaker Kaja Godek, a member of the committee that spearheaded the bill, claims that the legislation would halt abortions for malformed fetuses, and "represent the lives of three human beings every day," Agence France-Presse reported.
Now, she wants doctors to stop prenatal screening to prevent what she calls "eugenic abortion."
"The original idea behind prenatal tests has been completely distorted," she told lawmakers in January. "Instead of treating and preparing parents and doctors to receive a child and help him, it makes it easier to choose extermination."
More than 96% of Poles identify as Catholic and the issue of abortion is tied not only to religion and the country's resurgent nationalist politics, but also to its history as a formerly communist country.
"Under communism, due to a lack of access to contraception, abortion was widely practiced in Poland as a real means of contraception," said women's rights activist and former politician Barbara Nowacka. "After the fall of communism, the law was tightened and now we face even more draconian measures."
Critics of the bill, like Nowacka, are concerned what the bill will mean for women in Poland, many of whom are already traveling elsewhere in Europe for abortions.
"The underground will grow," she told CNN from her office in Warsaw.
"Abortion tourism. Women traveling to Czech Republic, Germany, UK and Ukraine, will grow again."