The 40-year-old singer-and-actress, who has twins Max and Emme with husband Marc Anthony, doesn't believe she would be able to look after her children alone because the stresses of motherhood are so demanding.

She said: 'I know a couple of people, both people I work with and friends, who have done it.

'I just don't know if I could do this, honestly. Now I know how much I rely on my partner.'

However the star - who plays a woman who is artificially inseminated just as she meets 'Mr. Right' in new romantic comedy 'The Back-Up Plan' - has a lot of admiration for mothers who do go it alone.

Jennifer added to the USA Today newspaper: 'I think it takes such an amazing person to do that. You get to a point in your life and you think about it, and I think it's a beautiful thing to be able to find the strength to do that on your own.

'That child will enrich your life. It's a beautiful thing to think that option is there.'

Despite taking a break from her career after the birth of her children in 2008, Jennifer knew she was ready to return when she saw 'The Back-Up Plan' script.

She said: 'I'd had the babies, so I was waiting for the right thing and I knew I wanted to do a romantic comedy.

'I felt like when I read the script, it was at the right place for me. It was the kind of romantic comedy that didn't feel typical, and the script was so funny."