SÃO PAULO — Thousands of demonstrators took to the streets of São Paulo on Saturday as protests sweep across Brazil in opposition to a bill that would further criminalize abortions. If passed, the law would equate the termination of a pregnancy after 22 weeks with homicide.

The bill, proposed by conservative lawmakers and heading for a vote in the lower house, would also apply in cases of rape. Critics say those who seek an abortion so late are mostly child rape victims, as their…