The 33-year-old actress who announced in May that she was expecting her first child with actor husband Daniel Gillies' has become a first-time mother after giving birth to a son according to a US report, reported E!Online.
The couple exchanged vows in 2004.
Cook had previously expressed astonishment over the constant compliments she got for her looks during her pregnancy.
"One of the best things about gestation is that people tell you that you look great, even when it is far from true. I don't turn down a compliment, so thank you!," Cook had said.