Johnny Galecki would "prefer" to have a baby girl.

Johnny Galecki

Johnny Galecki

The 'Big Bang Theory' actor and his partner Alaina Meyer revealed last week they are expecting their first child together and the 43-year-old star has admitted he is hoping for a daughter.

Asked if he had painted his nails bright pink as a hint he knows Alaina is carrying a girl, he explained on 'The Talk': "I get a little bored looking exactly the same way for nine and a half months every year playing Leonard.

"So we wrapped and I threw some blue in my hair, then I got superstitious that I was manifesting a boy, when I kind of prefer a girl...Don't play this tape for my child years from now!

"So, I painted my nails pink to try to even out the energy there."

During Johnny's appearance, show co-host Sara Gilbert revealed she'd burst into tears when her friend told her his happy news at the 'Big Bang Theory' finale wrap party - but had to pretend she was distraught about the show ending when she was asked about her display of emotion.

She recalled: "I'm sitting with Johnny and his girlfriend ... and he's like, 'I gotta tell you, we're expecting a baby.

"When he said that, I burst into tears, so tears are coming down my face ... and Stephanie, [make-up artist on 'The Talk'] sees me and she walks up and says, 'I know, isn't it so sad that the show is ending?'

"And I couldn't say anything, so I was like, 'Oh yes, yes.' "

Johnny and Alaina, 21, announced on Instagram that they were expecting a baby.

In identical posts shared on both their accounts, they posted two pictures of them together and wrote: "We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world.

"We ask that you please respect our privacy during this celebratory time for us and our families. There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."