Jennifer Lopez secretly suffered from post-partum depression aftergiving birth to twins in 2008.

The On the Floor hitmaker became a mum to son Max and daughter Emme, with her then-husband Marc Anthony, in February that year, but she initially feared she was incapable of forging a bond with the babies and her self-doubt sent her into a dark place.

Lopez credits parenting guidebook What to Expect When You're Expecting with helping her to compartmentalise her feelings, and it was her own reliance on the book which inspired her to sign up for the new big screen adaptation.

She tells Redbook magazine, "I remember after the babies were born, about seven to 10 days in, I was like, 'What is going on with me?' I felt sad and depressed and thought the babies didn't love me.

"I actually remember picking up the book (What to Expect When You're Expecting) to try to see what was happening to me, and it said how you have this huge hormonal drop about seven to 10 days after you give birth.

"It's called the 'baby blues.' But I just thought they didn't like me!"