Recent research has shown connection between fertility drugs and increased risk of womb cancer in women. A research team led by Dr Ronit Calderon-Margalit at Hadassah-Hebrew University in Jerusalem studied the effects of these drugs by comparing cancer incidence in 15,000 Israeli women 30 years after they gave birth.

The study revealed that five out of 567 women given drugs to induce ovulation developed womb cancer, this number was three times the incidence level for women who were not given such drugs. Researchers also found that intake of the drug clomiphene by 362 women increased the risk more than four times. Clomiphene tricks the body into making extra eggs by blocking hormone activity. Study showed smaller but significant increases in rates of breast cancer, malignant skin cancer, and non-Hodgkin's lymphoma linked to the drugs.

Some previous studies have linked ovarian cancer to fertility treatments but the recent study indicated no connection.

Jodie Moffat, health information officer at the charity Cancer Research UK, said it was difficult to draw any firm conclusions from the results.

Dr Calderon-Margalit said that the numbers are small, but says they carry extra weight because they make "biological sense" as tamoxifen, a breast cancer treatment which, like clomiphene, reduces sensitivity to oestrogen, was known to increase the risk of womb cancer.