Josh Duhamel is a ''little bit terrified'' about becoming a dad.

The 40-year-old actor is expecting his first child with his wife Fergie and their baby boy is due any day now.

Although he is very excited to meet his son, the 'Safe Haven' star is also nervous because once he becomes a dad he knows his life is going to change forever.

During an appearance on 'The Tonight Show with Jay Leno', he revealed: ''I got to tell you, I'm a little bit nervous. I thought I was going to be good, I thought I was ready for this and I'm a little bit terrified. I'm excited and terrified because I'm responsible for this little thing forever. I just got that.''

The couple have been preparing for the imminent birth of their son and have a bag ready for when they have to dash to the hospital.

As they wait for the Black Eyed Peas singer - who officially changed her name from Stacy Ann Ferguson to Fergie Duhamel earlier this month - to go into labour the couple have been enjoying spending some quiet time together.

Josh recently admitted he has been very impressed by 38-year-old Fergie's calmness during the pregnancy and her readiness for motherhood.

He said: ''[She's] unbelievable. The girl is so impressive.

''You never know how it's going to go. Some girls have a tougher time, some a little easier ... She's been happy, in good spirits, she looks great. Even at 8 and 3/4 months, she's still in great spirits and looking beautiful.''