As well as responding to the Roe v. Wade precedent review, regarding abortion access in the United States, the gatherings have been organized to draw attention to how expensive and difficult abortions can be in Australia, ABC reported.
Demonstrations were held in Melbourne, Sydney, Canberra, Perth and Hobart, the news outlet added.
According to Sky News Australia, nearly 5,000 demonstrators have gathered in Adelaide, and almost 1,000 in Brisbane.
Earlier in June, the US Supreme Court overturned the precedent established in the 1973 Roe v. Wade decision and ruled that states may regulate the practice of abortion. Some US states already have so-called "trigger laws" that would outlaw or restrict the practice of abortion, but allow exceptions such as in cases when the life of the mother is in danger.