Work times should not be cut for nursing mums, Key says after baby out until midnight.
Prime Minister John Key does not believe Parliament's hours should be reduced to make it more "family friendly", saying having children while in Parliament was "challenging but do-able" and it was up to each party to ensure nursing mothers had the support and time out needed.
Speaker David Carter is considering introducing special leave provisions for nursing mothers after Labour MP Nanaia Mahuta was in Parliament with her baby until midnight on Friday because of urgency.
She told the Speaker it was unfair to expect nursing mothers to be in Parliament late into the night.
Mr Key said it was up to the Speaker to decide on any new rules, but it was possible for parties to arrange leave to give priority to those who most needed it, such as nursing mothers.
Parties can have one quarter of their MPs away at any time without losing votes in Parliament.
He said it was up to the Speaker to decide whether to formally allow women to take babies into the House.
"There has to be a practicality about the way the House works. Without doubt, a mother who is also an MP has to balance some real challenges from time to time, but I think it is actually the whips and the Labour Party's responsibility to acknowledge those challenges and prioritise leave for that person."
Labour whip Chris Hipkins said Ms Mahuta had been given significant amounts of leave but there was extra pressure on leave during urgency. Ms Mahuta had agreed to work on Friday night after she was given leave for Thursday.
He had taken her off the speaking roster after she told him she had to bring the baby to Parliament.
Ms Mahuta has also called for more formal guidelines for those with young children, including whether they can be in the debating chamber while Parliament is sitting.
Mr Key said Parliament had become "increasingly friendly" for family life compared with the past. Parliament sits for three days a week on about 33 weeks a year, and the recesses were aligned with school holidays.
"So it's pretty accessible. It's better than it was."
Mr Key said he would not discourage anyone who wanted to stand for Parliament but also hoped to have children.
Green MP Holly Walker is expecting her first child in September, and said while any changes that made that easier were welcome she was hopeful that in the long term Parliament would reduce its hours and make Parliament a more realistic option for women.
In sitting weeks, Parliament sits until 10pm on Tuesdays and Wednesdays and ends at 6pm on Thursdays. MPs have caucus meetings and select committee meetings in the mornings.