Sandra Bullock feels under pressure to get pregnant.

'The Proposal' actress - who married motorbike enthusiast Jesse James in 2005 and is step-mother to his three children, Chandler, 15, Jesse Jr, 12 and Sunny, five - is frustrated people keep asking why she hasn't had children of her own.

She said: "It always seems that people want to talk about my uterus. I'm not talking about their vagina or their penis. Why are they talking about my innards?"

The 44-year-old star avoided falling pregnant earlier in her life because she didn't want to be a selfish mother.

She explained: "I didn't want to have a child without a partner and I loved kids too much to have them right then, because I knew that the minute I have children my life would change.

"And then I met Jesse and I went, 'Wow! There's that feeling of wanting to procreate because I love someone and I see him to be a good father.' "

Despite not giving birth herself, Sandra enjoys the challenges of looking after her step-children and loves them as if they are her own.

She explained to Britain's The Times newspaper: "A life is a life. Whether or not it came from your body should be secondary, in my opinion. If tomorrow I got home and went, 'Oh my gosh, I'm pregnant,' I'd be like, 'Wow! Isn't the universe amazing?' But what I learnt was that it's being more of a parent to care for a child that's not yours. It's harder."