Dieting destroyed my fertility

Kimberley Willmott, 35, is an office manager and lives in Cheam, Surrey with her husband John, a designer. Here she reveals with candour just how her fixation with weight meant that she could not get pregnant.

Staying slim has always been important for me but I never dreamed that exercising would leave me with a body that couldn't produce a baby. I'm not fat, but I have a natural tendency to be a bit plump if I don't watch what I eat. In my twenties, I was always a reasonable size, but I always thought I had a fat bottom and before my 30th birthday I resolved to do something about it. Little did I realise then just what the devastating effects of my quest for the perfect bottom would be.

I'm 5ft 2in, and at that time weighed about 8st 4lb. I aimed to lose about a stone but, as the pounds disappeared, I wondered what I'd look like if I just lost a little more and, after 18 months, I was down to just under seven stone. I loved my slim body and the exercise - I was going to the gym five times a week - and making sure my diet was as healthy and low-fat as possible.

Friends started saying that I was too thin, but I thought they were just jealous. I felt fantastic, but all the time I was destroying my fertility. And I didn't even realise, until we started trying for a baby when I turned 32 and I stopped taking the Pill.

I didn't get pregnant, but what was more of a surprise was that my periods didn't come back. While I was losing weight my periods must have ceased, but because I was on the Pill, I had no idea - because with that form of contraception, you get a "withdrawal bleed" every month. I knew that your periods could stop if you were underweight, but because I was still having a monthly bleed, I didn't realise it was happening to me.

I went to see my GP, who suggested it might have happened because I'd been on the Pill for so long, and I should give my system a few months to sort itself out. I've known my husband since my teens, and have been on the Pill from when I was 18, so this seemed a reasonable explanation and at first I wasn't unduly bothered. But then the doctor suggested I give it another six months, and I began to feel panicky, because I know how fertility declines as you get older.

Still, I kept on exercising. Friends who saw holiday photographs of me in a swimsuit were appalled at how skinny I looked. " Look at your arms!" they said. But all I could see was that my bum wasn't fat any more, and that was what mattered. My brother told me off, too. "You'll never have a baby," he said. "There's no flesh on you." But it didn't matter who told me, I didn't listen - my desire to stay slim was stronger than my desire for a baby.

The turning point came for me a few weeks later. I went to a shop near work where I hadn't been for a while, and the man behind the counter took one look at me and asked if I'd been ill. "Have you had cancer?" he said. I was shocked - I thought I looked fine, but obviously others didn't.

All the tests I had showed I was physically fine, just a little underweight, but eventually I was referred to Geeta Nargund, the medical director of the Diana, Princess of Wales Centre for Reproductive Medicine at St George's Hospital. By then, I hadn't had a period for two years, even though I was off the Pill. She felt my problem was weight related, and encouraged me to gain a little more - by then, I weighed almost eight stone. The levels of reproductive hormones are affected by body weight, and because mine were so low, my periods had stopped.

Blood tests showed that my oestrogen levels were postmenopausal, and ultrasound scans suggested that I had a very thin lining in my womb. If the lining of the womb isn't thickening up each month, there's nothing for a fertilised egg to be implanted into - and of course then it isn't shed, so there is no period.

I began eating things I hadn't touched for years, such as butter and peanut butter, but even though I got my weight up to eight and a half stone, my periods didn't come back. I thought I was never going to be able to become pregnant. I thought I'd mucked my body up for good. Even when I had put on more weight, and my oestrogen levels had begun to rise, I didn't get my periods back, which shows just how much damage I had done to my body.

My body image became an obsession, just like it is for millions of young women who want the impossibly slim bodies of models and film stars. Well, as far as I'm concerned, it's better to keep your chances of conceiving than doing all you can to lose weight.

Teenage girls desperate to lose weight simply don't understand the potential consequences. We're born with the shape we are, and there's only so much you can do to change it. By eating less and less and exercising more and more, you can do so much harm. All this damage is going on inside and you simply can't see what's happening - I certainly didn't.

What I did was so stupid. When I look back, I can see it was stupid, but at the time it seemed perfectly logical. I just wanted to be slim. We all want to be slim. And I still don't see anything wrong with that. But there's slim and healthy, and slim and unhealthy, and, as I found out, there is a very fine line between the two.

But now I am 12 weeks' pregnant, against all the odds - thanks to the follicle-stimulating hormone treatment I have undergone.

It has been expensive, but it's been worth every penny. Even now, when I say to people, "I'm pregnant," I can't believe it. But I also can't believe that I ever allowed myself to get into a state that jeopardised my chances of having a baby.