Judith Collins' 'motherly advice' for Jacinda Ardern

Judith Collins has some advice for Prime Minister and mum-to-be Jacinda Ardern: take help when it's offered, because you're going to need it.

Ms Ardern is due in June, and will become the second world leader in modern times to give birth while in office.

Ms Collins, who has one adult son, told The AM Show while the Prime Minister will be "constantly striving to be perfect", she doesn't have to be.

"Jacinda, you're going to get a lot of advice from people. You should just only listen to whatever suits you or your family," said the former Minister for Corrections, Justice, Police and Revenue.

"The other thing is, don't think you have to be perfect on everything. Whatever it is, you'll get through, in terms of family and everything else. You've just got to do your best.

"Every time anyone offers you help, take it. I have experience running a law firm and having a baby and doing study."

Sleep deprivation will be a hazard she'll have to deal with too.

"You've just got to be a bit nice to yourself sometimes," Ms Collins said.

Ms Ardern's pregnancy made headlines around the world. Since her announcement US Senator Tammy Duckworth has revealed she'll be giving birth in April - the first US Senator to do so while in office.

Ms Duckworth has been touted as a potential Democratic nominee to run against Donald Trump in 2020 for the presidency.

Newshub.