Her favorite part of caring for her son thus far is "probably the moment when he wakes up from a nap."
"He's sort of looking around and you kind of creep up and look over the crib and he looks up and he goes [Biel lets out a big sighing sound]. Just a gummy mouth, no teeth, just a big smile, happy that you're alive and you're just looking at him. That's probably the most magical," she told E! News in an exclusive interview.
Even though she loves those moments, she joked about what comes next.
"You quickly move on from it because there is a dirty diaper in your palm," she said, joking.
"Thank you EVERYONE for the Bday wishes! This year, I'm getting the GREATEST GIFT EVER. CAN'T WAIT. #BoyOrGirl #YouNeverKnow #WeDontEvenKnow #WeAreTakingBets," he wrote next to a pic of him kissing her stomach.