Johanna, 33, was 17 when doctors told her she had premature ovarian failure (POF).
It's thought that one in a hundred women go through the menopause when they're under 40, and one in 10 of these are under 30.
The "normal" age for menopause is debatable, but most doctors consider menopause to be early if a woman's periods stop before she is 45.
Johanna, a teacher from Clitheroe in Lancashire, had one period when she was 13, "and that was it," she says.
"I went back to the doctors a few times. They said it was normal for things to settle into some sort of pattern. I had the mood swings and the hot flushes but I put that down to puberty and being a moody teenager rather than the menopause. I started having a series of blood tests at 16 and, when I was 17, I was diagnosed.
"I had two great aunts and neither of them were able to have children, so I wondered whether it might be the same thing."
The causes of POF are described as primary or secondary.
Ovaries just stop working
Primary premature ovarian failure is when a woman's ovaries stop working. It's usually not possible to explain why this happens, but the reasons can include:
- chromosome abnormalities, such as in women with Down's syndrome
- enzyme deficiencies, where enzymes in the body affect the ovaries by damaging the eggs and preventing the production of oestrogen
- autoimmune diseases, where the body's natural defence mechanisms start producing antibodies that destroy its own tissues
Medical treatments that damage egg production
Secondary premature ovarian failure can be due to cancer treatments such as radiotherapy or chemotherapy. The risk of POF depends on the type of treatment given and the age of the patient.
Girls who have'nt reached puberty can tolerate stronger treatment than older women without losing their fertility. It might be possible to remove eggs for storage before treatment.
Surgery that triggers menopause
Other causes of secondary POF include surgical menopause, which is an operation to remove both ovaries, or having a hysterectomy, which is surgery to remove the womb.
Infections, such as tuberculosis and mumps, can also cause POF, though this is rare. Other infections linked to POF include malaria and chickenpox.
Risks of premature menopause
Women who have an early menopause have an increased risk of osteoporosis due to reduced oestrogen levels. Because of this, most doctors recommend HRT until a woman reaches the normal age of natural menopause (which is around 52).
Though she isn't on HRT, Johanna has been on the pill since her diagnosis. "It was ironic really, given that it is a contraceptive, but it balanced my oestrogen levels and I still take it now. I was also on calcium tablets."
However, the calcium hasn't been sufficient to protect Johanna's bones, which were affected from an early age. "I had various scans at 21. When the results came back, they revealed my hip bone was the same as that of a 65-year-old woman," she says.
"I've got very osteoporotic bones but it hasn't affected me a great deal. I haven't had any fractures but I have to be careful."
Coping with infertility
Women who experience an early menopause before they've been able to have children may find it hard to deal with.
Although women who have gone through early menopause can have children, it involves undergoing IVF using eggs donated by another woman.
The reality of having gone through the menopause didn't really hit Johanna initially. "At 17, you're not really thinking about having children. I didn't think a huge amount about it until I was getting to the end of university and the reality of my infertility sunk in. I became really quite depressed and was on medication for a few years."
Johanna's outlook now varies. "I can feel quite philosophical and I can think, 'What's happened, happened'. But sometimes it hits me very hard, expecially as a lot of my friends are having children or have had children. I try to cope with it by spoiling my godchildren rotten.
Support for premature menopause
Counselling or support groups may be helpful if you have had or are experiencing POF. The Daisy Network is a charity dedicated to POF, and runs self-help groups for women.
"The Daisy Network is a huge source of support," says Johanna. "It's not something that people tend to talk about much, but it really helps to know there are other people out there who have gone through the same sort of thing.
"They have regular support meetings and a quarterly newsletter, which is informative and always has news of the latest research, which makes me think there's always hope. There's also a telephone network, which I haven't used that much but I know it's always there."