Actress Megan Fox has vowed to be "more cautious" about the roles she accepts now she is a mother, because she is worried her son will be embarrassed by her past choices.

The Transformers star and her husband Brian Austin Green became parents to Noah in September (12), and Fox admits her outlook on life has altered now she has a baby in her life - and she is convinced motherhood will affect the movie parts she takes on.

In her first interview since giving birth, Fox tells Britain's Daily Mirror newspaper, "It changes your perspective about being overly sexual in a film when you have a baby.

"I'm going to be more cautious about choosing films because I'm already thinking about when he's in school and his friends are going to be showing him my photo shoots with me in a bikini and he's going to be horrified. So that will deter me from making some of the choices I made before."

However, the 26 year old reveals she worries about her future in Hollywood, adding, "It's scary because unfortunately women in the film industry don't seem to hold their value as they get older so it's scary for all of us.

"I relate it to being like a basketball player who is only 33 or 34 but people say he is geriatric because you top-out young. It's the same thing for actresses. I'm 26 but already time is a tickin'.

"I've only got a few years left being so good but I'm thankful for having the marriage that I have and having a best friend and partner because that makes me feel safe and comforted in knowing that he's going to grow old with me and love me no matter what and value me no matter how old I get."

Opening up about her life as a new mother, Fox insists she has no imminent plans to slim down following the birth of Noah - because she only gained 23 pounds (10 kilograms) during her pregnancy.

She explains, "I'm still 10 pounds heavier than I was but I don't want to kill myself trying to get back into shape because it's not a priority right now. I'm too in love with Noah and I don't want to be away from him. I don't want to be at the gym, I just want to be home."