Women who give birth LATER have lower risk of womb cancer



14:40 GMT, 26 July 2012

Pregnancy protects against womb cancer later in life

Pregnancy protects against womb cancer later in life

Mothers who have their children earlier are less likely to suffer from complications during the pregnancy. However, a new study has found giving birth later has its advantages.

Researchers found women who have their last baby when they are 40 or older have a 44 per cent decreased risk of developing womb cancer than those who have their children by the age of 25. They added that this protective effect continued for decades after.

Womb or endometrial cancer strikes the endometrium, the tissue lining the womb and is the most common gynecological cancer in the U.S and UK. Most cases affect women in their fifties and sixties.

A team from the University of Southern California found the risk begins to decrease after age 30 by around 13
per cent for each five-year delay in last births.

Compared to
women who last give birth before age 25, those who have their last child
between age 30 and 34 reduce their risk by 17 per cent and those between
age 35 and 39 reduce their risk by 32 per cent.

Study leader Dr Veronica Setiawan said: 'The size of this study definitively shows that late age at last birth is
a significant protective factor after taking into account other factors
known to influence the disease – body weight, number of kids and oral
contraceptive use.'

The study, believed to be the largest of its kind, examined pooled data from four cohort studies and 13 case-control studies. Funded by the National Cancer Institute, the research examined a total of 8,671 cases of endometrial (womb) cancer and around twice as many control subjects.

Dr Setiawan said: 'We found that the lower risk of endometrial cancer continued for older mothers across different age-at-diagnosis groups, including under 50, 50-59, 60-69, and over 70 – which shows that the protection persists for many years.

'Protection also did not vary by the two types of the disease: the more common Type 1, which we think is related to estrogen exposure; and the more rare, but more aggressive and deadly, Type 2, which have been thought to develop independent of hormones.'

Endometrial cancer is the fourth most commonly occurring cancer in women. In 2007 in the UK, 7,536 new cases were diagnosed.

More research is necessary to determine why late age at last birth might protect against endometrial cancer.

However Dr Setiawan said several potential mechanisms are being considered. It may be that women capable of becoming pregnant at an older age may possess a healthy endometrium or experience fewer menstrual cycles without ovulation. Another possibility is prolonged exposure to the hormone progesterone during pregnancy may be especially beneficial at older ages.

She concluded: 'This study shows an important protective factor for endometrial cancer, and when the exact mechanism by which it protects women from getting the disease is known, it can help our understanding of how endometrial cancer develops and thus how to prevent it.'

The study results are now available online in the American Journal of Epidemiology.