Acting Prime Minister Winston Peters says Opposition Leader Simon Bridges made a fool of himself by labelling Prime Minister Jacinda Ardern and partner Clarke Gayford "pinkos", and said the baby would be going to school in boys' clothes because of its parents' politics.
"I think the Latin phrase would be that's a res ipsa loquitur situation - the thing speaks for itself," he told journalists at Monday's post-Cabinet news conference.
"When someone makes a fool of themselves? Do you want me to elaborate my views? I think the thing speaks for itself," Mr Peters said.
Res ipsa loquitur is a doctrine in the law of torts that says the incident was of a type that doesn't generally happen without negligence.
Mr Bridges has been under fire for a series of comments made on Radio Hauraki on Friday morning.
When the hosts asked Mr Bridges if it's politically correct to have a female baby and if it should be considered gender-fluid instead, Mr Bridges said, "Only under a Labour government... She should be going to school like in boys' clothes right?"
Appearing on The AM Show on Monday, Mr Bridges said the comments had been light-hearted.
"I wish Jacinda, her partner and little Neve all the very best. Just absolute happiness," he said.
In the interview on Radio Hauraki, Mr Bridges also said Ms Ardern got "some funny ideas" going to university.
Mr Peters doesn't entirely disagree with that sentiment.
"Separate from the thing on Radio Hauraki, yeah I've seen people get funny ideas when they go to university. They get to be snobbish, arrogant, a lot of them go into the written professions - present company excepted," Mr Peters told the room full of journalists.
When asked whether he also went to university, Mr Peters answered, "Yes, I did" - though with a characteristic twinkle in his eye.