The `Homeland` star gave birth to her first son, Cyrus, on December 17, but doesn`t plan to stay at home with him for too long.
She told Us Weekly magazine: "I`ve always wanted to have kids, but I`m glad I didn`t until now. When I was thinking about [working and being a mother] originally, I was really nervous about it.
"I think I would make a lousy stay-at-home mom. It just wouldn`t suit me. I feel so fortunate, in that I`ve had this arrow-straight focus that I wanted to act."
Claire who is married to fellow actor Hugh Dancy, 37, added she feels "lucky" to have such a great partner who helped guide her through her pregnancy.
The 33-year-old actress - who was in a six-year relationship with Australian musician Ben Lee and dated actor Billy Crudup before she met Hugh - added: "Hugh was just the right partner for me. I got very, very lucky.
"There`s only so much credit you can take when it just sort of works, you know? And obviously we work hard at maintaining our relationship - that is central to both our lives - but at the same time, it`s just this kind of ease that I can`t really account for."