Halle Berry mistook her pregnancy for kidney stones.

The 46-year-old actress is expecting a baby with her fiancé Olivier Martinez and she admits the news initially came as a total ''shock'' to her as she had no inkling she was with child.

She said: ''I was at the doctor's when they told me and I was completely shocked ... I didn't see it coming. I went to the doctor because I thought I had kidney stones or something. So it was a massive surprise.''

Halle's five-year-old daughter Nahla - her child with ex-boyfriend Gabriel Aubry - is as excited as her mother and Olivier about the baby, and the Oscar winner is thankful to God for the ''amazing gift'' of a second child.

She added to the new UK issue of HELLO! magazine: ''[Nahla's] really happy. Not long ago she asked God for a little sister, but I tried not to get her hopes up. At 46, I didn't know if I'd be able to get pregnant again.

''Olivier and I have always wanted to be parents. But I didn't want to get my hopes up ... God made the dream come true. This pregnancy is like a miracle for me, an amazing gift, because this child was as wished for as it was expected.

''It's like a renewal of life ... Good things happen too.''

Despite two divorces and a bitter split from Nahla's father Gabriel - with whom she still has a difficult relationship - Halle can't wait to tie the knot again with Olivier and she won't let her past romantic woes affect her future.

When asked whether she still believes in life-long love, she insisted: ''Absolutely. I'm an incurable romantic - that's the only reason I'm marrying again. Just because things haven't gone well in my past doesn't mean that I've given up.''