The Scream star reveals Christina MCLarty hasn't had as smooth a pregnancy as she did with their son Charlie, and having to keep an eye on the now-two-year-old boy is proving to be a tough task.

"I think the second pregnancy is a little harder than the first," David told "She's got morning sickness on this one."

He continued, "Being pregnant and watching a little rascal that's firmly in his terrible twos is pretty difficult. She's a trouper, she's doing great. She's my hero."

The couple is currently preparing Charlie for life as a big brother, but David worries he will act up when the new baby arrives.

"Charlie is really cute about it," he explained. "We have little books that prepare him. We'll see how it goes when it all goes down. He's a tricky little bugger."

David and Christina, who wed last year (15), announced their baby news in October (16) by sharing a video of Charlie kissing a sonogram photo and saying "hi" to his unborn brother.

"So incredibly blessed and honoured that my wife @christinaarquette is pregnant with a baby boy!" the actor captioned the Instagram post. "Thank you Christina and humbled gratitude to G-D (God) for this tremendous gift! Charlie and Coco are so excited and I am over the moon!!!"

Coco is David's 12-year-old daughter with his ex-wife Courteney Cox, who he separated from in 2010 after 11 years of marriage. They finalised their divorce in 2013.