Jennifer Lopez compared pregnancy to "an invasion of the body snatchers".

The US singer and actress - who is mother to two year old twins Max and Emme with husband Marc Anthony - found the way her babies took over her body during their birthing "weird" and wanted her latest role in the 'The Backup Plan', about a pregnant woman finding love, to accurately reflect this.

She said: "I wanted to put as much in as we could that was real: the overeating, the burping. Why not? It's funny too.

"Pregnancy and giving birth are weird, strange. The growing life inside you - it's like an invasion of the body snatchers."

Jennifer, 40, also learned much about the differing attitudes of men and women through observing how her young twins act around each other.

She added: "Max is always climbing out of his cot to get in Emme's. But then they fight like cat and dog.

"I've figured out the difference between men and women by seeing their innate characteristics. She is very careful, and you can see her thinking; men don't think, they attack and deal with the consequences.

"We approach life and love in different ways."

'The Backup Plan' featuring Jennifer and Alex O'Loughlin is released in Europe this May.