Offspring's Kat Stewart has given birth to a baby girl.

Kat Stewart has a new baby in the house!

In an interview with The Daily Telegraph, actress Kat Stewart, has announced she has given birth to a baby girl.

Except, there’s a catch (isn’t there always?).

Stewart welcomed her darling daughter into the world more than five weeks ago and up until now, barely anyone knew.

On March 16, Stewart had baby, Georgia – or Gigi for short.

“It wasn’t a conscious thing (to keep Gigi’s birth secret),” Stewart told the paper. “I haven’t been hiding her. I’ve just been pottering around at home.”

Gigi was born just before the filming of the sixth season of Offspring was set to begin, and Stewart confirmed she’ll be bringing her baby onto the set.

Billie (Stewart) and Nina (Keddie) on Offspring. Image via Facebook.

"Gigi is a very pleasant surprise. I'm only five weeks in. I wouldn't normally go back to work this early but Offspring is a family," she said.

"Archie [her four-year-old son] was on set with me when he was really little and I'm doing the same with Gigi."

Stewart also said that Asher Keddie, who plays the role of Nina on the show, will be bringing her one-year-old son, Valentino, along, too.

"We'll have Asher's little boy here too. It is a family-friendly atmosphere. It feel really right and really nice. I think it will only enrich the experience of doing the show having them around.

"It is so lovely to be spending time with Asher again," Stewart said. "We haven't seen much of each other since the last series and Valentino is a gorgeous little boy.

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"We said 'how much sleep did you get' and we both looked at each other and said 'not much'.

"I'm going to be doing [Billie] on less sleep [but] as soon as you let go of the idea of getting enough sleep it is quite liberating," Stewart said.

As the countdown for Offspring begins, everyone is still wondering where the story line will lead after it appeared to finish up last season.

"There is always the element of surprise with Offspring," Stewart admitted. "I've read the first couple of episodes. I feel like the characters are going deeper. There is more stuff to discover."

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"I really didn't think it would happen," Stewart said about the renewal of Offspring. "It was the best experience I've had in a show. You form such deep relationships with the people and also the characters."

Despite falling in love with the show, many fans have shared their concerns about the sixth season, but Stewart has tried to reassure them.

"I feel really confident we'll be able to deliver something great. I don't think we're going to coast on some sort of legacy. We're really aware of that and all want it to be as fantastic and awesome as it can be."

We can't wait to get a glimpse of the new season of the show - and baby Gigi.