Labour MP Tāmati Coffey and partner Tim Smith expecting a baby

Labour MP Tamati Coffey and his partner Tim Smith announced at the 20th anniversary of the Big Gay Out that they were going to have a baby. Photo / Peter Meecham

Labour MP Tāmati Coffey and his partner are expecting a baby.

The MP for Waiariki made the announcement today at the Big Gay Out on the main stage alongside Prime Minister Jacinda Ardern.

"I wanted to seize the opportunity at the biggest gay event in the country right now to share the news me and my partner over there are expecting a baby in July," Coffey said.

His words were met with huge cheers and applause from the packed audience.

Coffey said he "applauded" the modern families out under the "rainbow umbrella".

"What I love about this, is it is a day to all come together, all types of people under the rainbow umbrella, it is a beautiful thing, there are all kinds of modern families going on today, and I applaud that."

The former TV host and his partner Tim Smith have been together for over a decade, and had a civil union in 2011.

"It has been a long time coming," Coffey said.

Tamati Coffey, Prime Minister Jacinda Ardern and Grant Robertson onstage at the 20th anniversary of the Big Gay Out. Photo / Peter Meecham

"I turn 40 this year and if ever there was a perfect time it is now."

"What better announcement is there than that?" Ardern said following his speech, to further cheers.

Coffey told the Herald the surrogate mother was a "friend of a friend", and she was about 20 weeks along.

"It has been getting hard keeping it a secret, especially with some family knowing about it, but we wanted to wait for a safe time to make the announcement.

"It has been hard for [the surrogate mother] too [not telling anyone], and she can make her announcements as she feels comfortable."

They knew the sex of the baby, but would be keeping it secret "for a little longer"," Coffey said.

"We actually just decided this morning to make the [baby] announcement, the time just felt right.

"We are hoping to celebrate with all the different kinds of modern families here today."