Two separate marches merged into a demonstration of 4,000 people in front of parliament, where lawmakers were debating amending the constitution to tighten Poland's anti-abortion law, already among the most restrictive in the EU.
"I am for life," said Miroslawa Kledzinska, 64. "God gives life and only he has the right to take life away."
Poland's abortion law allows termination of a pregnancy until the 12th week if the mother's life is in danger, the fetus is irreparably damaged or the pregnancy is the result of rape or incest.
President Lech Kaczynski has put forward one of three separate proposals to amend the constitution to prohibit abortion completely.