Ms Ardern, who is expecting her first child in June, held discussions with Obama after he received a traditional Maori welcome at Government House.
"I asked him about parenthood and he had tips that I will probably long remember," the centre-left leader told reporters, without giving further details.
Obama and his wife Michelle have two children, Malia and Sasha.
Ardern said they also discussed the state of progressive climate change and engaging young people in politics.
Obama is in New Zealand for a three-day trip centred on a corporate speaking function on Thursday night organised by the NZ-US Council.
He has also played golf with former prime minister John Key.
Obama's corporate-sponsored speech, for which is reportedly being paid NZ$400,000 (US$290,000), is being held behind closed doors and he has largely avoided the media during his trip.
