There's a Valentine's Day bombshell on the way in The Big Bang Theory

The episode saw Howard and Bernadette opt to spend Valentine's Day together at home in their new hot tub, but their plans changed when they found a rabbit fighting for its life in the water. The pair named him, rather fittingly, Valentino and spent the day looking after the furball.

Bernadette became somewhat smitten with the rabbit and Valentino became the sole the recipient of a Big secret: Bernadette is pregnant.

If the news feels a little unexpected, there's a good reason why... "We've touched on the idea of Bernadette and Howard and children here and there but we didn't really have plans to pull the trigger at any point," reveals showrunner Steve Molaro. "It wasn't even part of the outline for the episode."

"We were writing it and getting toward the end of the story and I guess maternity was in the air because Bernadette was holding this wrapped up bunny and they named it and we were writing the final page of that storyline. Half-kidding, I said, "What if Bernadette tells the rabbit, 'We'll find another time to tell him I'm pregnant.' " The room had such a strong, positive reaction to it. We thought it seemed like an organic moment and we decided to put it in."

"Part of what makes the time right is that it maybe doesn't feel completely right — and that's what we 're attracted to," he continues to the Hollywood Reporter. "If it seemed like the obvious time, it wouldn't be exciting for us to do it. Babies take a long time to come. This baby wouldn't be due until halfway through season 10 of the show. We're in the middle of our ninth year, why not now?!"

"Many emotions were felt" when stars Melissa Rauch and Simon Helberg were told the news. And we won't have to wait long to see how the news plays out on camera.

For now only Valentino the rabbit knows, but that'll change in the next episode, says Molaro.

"You get to see her tell him right at the beginning of the episode and it turned out beautifully. He will experience many emotions! We really dig into the entire group and everybody's reactions to it. They're mostly positive but obviously with some surprise and concern about what this means for the future."

The Big Bang Theory airs on E4 in the UK