The Australian House of Representatives has changed its rules to allow lawmakers to breastfeed and bottle-feed in the chamber.
Under the old rules, MPs could only take babies into the public galleries or offices of the parliament building.
The leader of the house welcomed the changes to "antiquated" practices.
Breastfeeding in parliament is a controversial issue in many countries, and lawmakers have been criticised for taking their babies to sessions.
The new regulations in Australia mean MPs' infants will no longer be considered as "visitors", banned from entering the chamber of the lower house.
The changes were approved after a recommendation from a parliamentary committee.
"No member male or female will ever be prevented from participating fully in the operation of the parliament by reason of having the care of a baby," House Leader Christopher Pyne said.
"There is absolutely no reason that rules should remain in place which make life in politics and the parliament more difficult for women."
Forty of the 150 members of the House of Representatives are women, and three have had babies since March, the Associated Press news agency said. Four other MPs are reportedly due to become fathers.
Last year, Assistant Treasurer Kelly O'Dwyer was reportedly advised to express more milk in order to not miss sessions in parliament.
The subject is a sensitive issue in many parliaments around the world. In January, Spanish MP Carolina Bescansa, from the Podemos (We Can) party, was both criticised and commended for by taking her baby into parliament and breastfeeding him.
Iolanda Pineda, of the Socialists' Party of Catalonia (PSC), also took her baby into Spain's upper house of parliament in 2012.
Italian politician Licia Ronzulli was first pictured with her baby in the European parliament in September 2010 when the child was six weeks old.
Last year a group of MPs in the UK called for a ban on new mothers breastfeeding their babies in the House of Commons chamber to be overturned.
However others warned it would risk ridicule from the tabloid press.