Labour MP Tāmati Coffey and partner Tim Smith hope to raise more than one child if they "work out how to do it the first time".
The MP for Waiariki, confirmed this afternoon that Smith was the biological father of the baby due in July, and their surrogate mother was "a friend of a friend".
Coffey announced the news at the Big Gay Out in Auckland yesterday and was met with applause and screams of excitement.
Until yesterday Coffey and Smith had only told a few family members, friends, and colleagues.
Not even Prime Minister Jacinda Ardern was in on the secret until Coffey called her yesterday morning, with a spontaneous idea to announce the news to the crowd.
"I called her to check it was okay. I didn't want to steal her thunder, but she said 'I would love to'."
Ardern has not yet given Coffey advice about juggling parenting and Parliament, but he is excited for those conversations tomorrow when he meets with fellow party members.
"No doubt they will be full of advice. Hopefully, they have lots of hand me downs. Kids go through clothes very fast so I really look forward to those!"
Coffey said although their child would have just Smith's genes, they would both be dads.
"We are both in this as parents."
The couple had a civil union in 2011 and had talked about a family for a long time.
They hope to get married in the presence of their future child, or children.
"Even when we got a civil union, we said one day we would work towards parenting. We weren't sure how we were going to but we knew we would do it. Then when the marriage equality bill passed, we said let's going into full marriage when we have kids.
"If we work out how to do it the first time, we would love to raise a couple of kids."
Coffey said finding a surrogate was not a quick task.
"When a friend of a friend put their hand up, that was amazing. It makes the process a whole lot easier. It's not like you can go into a clinic and choose from a list you know."
He said the woman was not based in Rotorua.
Both Smith and Coffey's families have been well involved in the family planning.
"It has been really important for us to take our parents with us through this journey. It is a new thing for both of our families, having conversations around surrogacy."
Coffey told NZME yesterday that he and Smith knew the sex of the baby.