Fertility drug labels in the US are to carry ovarian cancer warnings following reports of a possible link between such hormonal treatment and the disease.
The American Collaborative Ovarian Cancer Group, based at Stanford University, California, reviewed the findings of 12 major studies of ovarian cancer and concludes that fertility drugs may triple the risk of women developing the disease.
Earlier this year, The Lancet published a study from the Netherlands which cited 12 cases of ovarian cell tumour in women undergoing fertility treatment.
The authors concluded that drugs to stimulate ovulation should only be given after "proper assessment" of the ovaries.
Some observers believe that the chemicals produced naturally by the body during ovulation may somehow cause ovarian cancer. Where hormonal fertility drugs are given to women having difficulty conceiving these act to stimulate egg production and so may possibly increase the risk of cancer by this means. Dr Simon Fishel, scientific director of Nurture, the infertility clinic at Nottingham University, estimates that one cycle of fertility drugs may be the equivalent of up to two years' natural egg production. Some women, in an attempt to become pregnant, may have as many as 20 such treatments.
Another unsolved question around prolonged fertility treatment is whether it brings on an early menopause because, quite simply, all the body's eggs are used up.