A ruling by Poland's Constitutional Tribunal that abortion on the grounds of foetal defects contravened the constitution came into effect in January, triggering a near total ban on pregnancy terminations and widespread protests.
People holding candles and carrying banners saying 'not one more' and 'indifference is complicity', marched through dozens of towns and cities on Saturday, according to organisers, including Pszczyna, southern Poland, where the woman lived.
Activists say the death of Izabela, a 30-year-old woman in the 22nd week of pregnancy whose family said died of septic shock, as a result of the ruling.
"The anti-abortion law in Poland kills Polish women. It is cruel, it is terrifying," a woman attending a protest in Pszczyna said in a comment aired by a private broadcaster TVN24. "It is inhuman and I hope that this situation will contribute in some way so that Polish women will not have to die," she added.
The government says the court ruling was not to blame for Izabela's death, rather an error by doctors. Poland's health minister Adam Niedzielski pledged to issue guidelines to make it clear when terminations were legal.