Christina Aguilera has put Britney Spears and Lindsay Lohan’s troubles down to lack of self control.

The singer – who recently confirmed her pregnancy – claims that Hollywood’s most troubled twosome lack the discipline necessary to shun drugs and alcohol.

She tells Glamour magazine, "When you hit 20 or 21 and you're around drugs and alcohol, everyone has a moment when they like to dabble in it and express themselves. It's called being young but there is a boundary.

"You see all of these horror stories about people that have died of drug overdoses, people that have taken it too far and ruined their lives, and for me, I had so many things that I had yet to accomplish. It was just a matter of thinking, I don't want to waste any time, and sticking to the plan."

The 25-year-old – who unlike Spears and Lohan has managed to avoid drug and alcohol related meltdowns – also discussed the controversy surrounding Brintey’s lacklustre MTV VMA comeback performance.

She adds: "Everyone has their own ways of choosing what's best for them. I have no problem with telling someone, 'Hey, I have to do a show tomorrow. I want to do a good job and be on my game'.

"Sometimes I wish I could go out to a party or a club and just be able to be free, but there's a consequence with the temptation. You know you'll feel it the next day when you wake up. There are too many things I have to accomplish."