Geri Halliwell has told how she believed she had destroyed her chances of having children - and regards her unborn baby after a short-lived romance as 'quite a miracle'.

With a long history of an eating disorder that reduced her from buxom Ginger Spice to stick-thin waif, Miss Halliwell even considered adoption because she feared she would not be able to conceive.

Speaking for the first time about her surprise pregnancy, the 33-year-old - whose baby is due at the end of May - told of her years of suffering from bulimia.

'It's a particular joy to share my news as it's widely known that I had a raging eating disorder for many years,' she told Hello! magazine at her home in Los Angeles.

'This affected my menstrual cycle so I felt very worried that my fertility could be affected, because I'd screwed around with my body shape so much.

'When, finally, I did get my periods back, they were very erratic, so I feel this baby is quite a miracle - a completely happy accident.' She said that while on holiday with friends in the South of France she told them she was thinking about adopting as she was so desperate for a child. 'Pregnancy, unlike my music career and business affairs, was something I could not control,' she said. 'I confided that I now felt I had enough heart to love a child that I did not actually give birth to. And I was genuinely considering adoption.'

Just two months later, she discovered she was pregnant after starting a romance with British scriptwriter Sacha Gervasi, who has been a friend for years. 'It seemed to me like the immaculate conception because I'd given up on the idea,' she admitted.

Fertility problems are a common side effect of eating disorders such as bulimia and anorexia nervosa.

Lack of nutrition and unhealthy weight can damage the major organs and cause hormonal imbalances which interfere with ovulation.

Although 75 per cent of women who get over disorders can go on to have children, many never get their bodies back to normal.

Miss Halliwell first suffered from bulimia as a teenager and, again, while in the Spice Girls. When she left the group, her weight dropped even further after she became obsessed with dieting.

After seeking therapy, she has managed to overcome her problems in the last three years. But Miss Halliwell admitted her system was still so erratic that it was not until she was seven weeks pregnant that she realised she was expecting.

She said: 'Absolutely my first reaction, way before fear and practicality set in, was to say "Thank you, God". My instinct was just pure gratitude. I jumped for joy. Mine may not have been perfect circumstances for a child, but whose ever are? I just felt so lucky.'

She says she plans to be a single mother as she and Gervasi are no longer together, although they remain good friends and he will play a part in bringing up the child.