Dear Clarke,

First of all, congratulations. I watched you standing next to Jacinda as she said that she and you were “really excited that in June our team will expand from two to three, and that we’ll be joining the many parents out there who wear two hats”. You looked seriously chuffed alongside your partner, our progressive new prime minister, as she announced that you two would be having your first baby in June and you would be a stay-at-home dad. And so you should. I know the feeling. I left my magazine literary editor job to look after our daughter when my partner had to go back to work after six months.

But ditch the idea that you’ll only need two hats. Some days it seems more like 10. Gather your extended families, your finest whanau, around you. You might not struggle to pay the bills but you’ll need all the help – the cheer and succour, the hard-won wisdom, the babysitting – you can muster. Of course, you’ll have the country behind you too, as your partner said: “New Zealand is going to help us raise our first child.”

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I heard your news a couple of hours after everyone else, because my partner and I were on a date. Our child, Gala, has been doing three mornings at daycare while I freelance, and that day was the first full one she was in. We had a leisurely lunch, Brazilian. DEE-licious, as Peppa Pig says (you’ll learn). But it was a rare occasion, Clarke: only our third date in two years. I know you won’t be like us. You’ll be flying around to launches and speeches with your baby momma PM, your child clocking up the air miles, before long filling up a third passport with stamps of all shapes and colours.

We know Jacinda found out just six days before becoming prime minister-elect. I had a dad feeling it would happen sooner rather than later. It was the way she was talking about it, the way she clearly adores kids, as you appear to. It was still a surprise, she said, because you had been told you’d “need some help”. At least you don’t have to ride that rollercoaster.

Play Video 1:48 New Zealand PM Jacinda Ardern announces she's pregnant with first child – video

To be honest, Clarke, my first three months at home were a shock – and our child was six months old by then. If you think you might get time during the day to do some voiceovers or check edits of your fishing show, think again. It’s a non-stop whirl of dressing, feeding, changing, strolling, singing, washing, cleaning, playing, soothing, sleeping. Deep rinse and repeat.

But you get efficient, fast, and it’s lovely being a stay-at-home dad. Total strangers smile at you. When you have a stroller, cars that would normally try to run you down at stop signs and zebra crossings wave you across. And when your child smiles for the first time, your heart will jiggle a little in your chest. Later, she or he will give a tiny chuckle, and soon, sigh with happiness. And you will think: we made that, aren’t we clever. And lucky.

It won’t always be easy. You’ll lose so much sleep you’ll think a good part of your brain has slid out your ears. You won’t believe how alert you will be to every snatched breath, every pained squawk. You’ll worry about everything your child does and doesn’t do, and you’ll praise the wisdom of whichever government instituted free doctor visits and prescriptions for young ones. But the best things usually aren’t easy.

You’ll be a great dad, Clarke. You look like a man who loves not just his partner but her life project, a man completely at ease with her power and pay packet. As all men should be.

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Don’t worry about Winston Peters running the country for six weeks. Jacinda said she intends to be “fully contactable” during her truncated period of maternity leave (which her government has increased to 22 weeks from July). “Instead of being out of the country, I’ll be in Point Chev,” she said.

It’s good that you know the sex of your baby so early. It’ll give you time to agree on a shortlist of names and to buy some of the roomfuls of baby stuff you’ll probably never use. Our wily older ultrasounder said around the three- or four-month mark that our little bundle looked a picture, chromosomes and nuchal fold all in order, and he was pretty sure it was a girl. Lots of fathers tell you they’d just love a boy, but I know you will not give a fig. (Girls are great.)

Here’s what to do, Clarke. Go for lots of walks, in nature. Give your partner back massages on demand. Listen to her – the country’s – woes. Make her laugh. And when the big day comes, grip her hand, not too tight. Stroke her hair. Whatever she asks.

And when you hold that little puffing nugget in your shaking hands, you’ll both know something you never did before.