Ovarian cancer

Women who have their first child later in life greatly reduce the risk of developing ovarian cancer, researchers believe. The risk falls by 10 per cent for every five year period the woman waits before conceiving.

This discovery, which scientists seem unable to properly explain, was made by researchers in Sweden. The country has the world's highest incidence of ovarian cancer. It tends to strike young women and is usually fatal.

It is the largest study of its type into ovarian cancer and involved the analysis of 4,729 victims. Of those, only 55 cases were reported among women who had their first child when they were over 35 years old. The 30 to 34 year group was the next lowest, with 232 cases reported. The highest was among those women who'd had their first baby when they were aged between 20 and 24; this group had 31 per cent of all cases.

The research team, headed by Prof Hans-Olov Adami of University Hospital in Uppsala, Sweden, conjectures that pregnancy may "drive out" malignant cells from the ovaries. As older women are more likely to have these cells, later pregnancy may offer some protection.