The baby will be the second for Hipkins and partner Jade.
He will also be spending time looking after the couple's first child, Charlie, who turns two in October. He will also be doing most of the cooking, which he loves when he can get the time.
"I do a mean lasagne, I do good smoked salmon fettuccine. I do fish pie," he said.
"Fish pie is quite good because you can get all the cooking done while Charlie is having his mid-afternoon sleep and put it in the oven in the evenings. Slow-cooker meals are quite good because you can bung on early in the day and it is quick and easy to serve up in the evenings. And roasts are always easy."
And he expects to be doing the cleaning and washing, including hand-washing for hand-knitted clothes.
"People do all these hand-knits for you which is great until the baby pukes all over them and you've got to hand wash them."
Hipkins says he already spends quality time with Charlie every morning with him, getting him up, having breakfast together and dropping him at day care.
They garden together, too. Last weekend they went to the garden centre to get strawberry plants for winter planting.
"He loved it. I had to stop him eating topsoil at one point."
So does being a young parent make him a better Minister of Education?
"I feel like being a parent has made me a better person overall but having said that, I don't think having children is a prerequisite to being a good Minister of Education.
"Other people have done it who don't have children or have grown-up children and I think they are just as good at the job. "
The main thing was to listen to people, including parents and teachers.
"I think it has made me a slightly more empathetic person probably than I was before I had kids."
Hipkins, one of the more youthful-looking MPs , will be celebrating his 40th birthday tonight with a dinner out, although the birthday is actually next Wednesday, and Fathers' Day tomorrow is likely to be marked with a family brunch at Mitre 10.
"We are regulars there," he said. "They know us by name, and it has a children's play area too."
The new baby is a girl, says Hipkins. "Perfect arrangement, one of each."
The new baby will be subject to the same publicity regime as Charlie, who has no public photos, including on Face Book.
Hipkins: "I want him to be able to grow up like a normal Kiwi kid and I want him to have his own space to grow up and be a kid and not be public property. I accept that I am public property. That doesn't mean that my family are."
Hipkins will continue to be paid his ministerial salary – as Jacinda Ardern was when she took time off. There is no mechanism to stop MPs' pay and they are not eligible for the ordinary paid parental leave scheme.
Associate Education Minister Tracey Martin will pick up most of Hipkins' education work. Iain lee-Galloway will take over Leader of the House duties. And State Services and Ministerial Services will be farmed out to others.
