Birth size predicts breast cancer risks

Women born bigger and longer are more likely to develop breast cancer later in life than others.

Breast cancer is the leading cause of cancer deaths among women worldwide. Previous studies regarding birth size and the related breast cancer risk have yielded inconsistent results. To study the association between the size at birth and the risk of developing breast cancer, researchers from America examined 32 studies comprising 600,000 women, out of which 22,000 women had breast cancer.

After considering established risk factors such as age and late menopause, the researchers found a strong association between breast cancer risk and birth size, birth length and head circumference. Of the three, birth length showed the strongest link. It was noted that the women with recorded birth weights of 4 kg or more had a 12 percent higher chance of breast cancer than those weighing 3 to 3.5 kilograms at birth.

The researchers estimated that birth size might be responsible for up to 5 percent of all breast cancers in women up to the age of 80. The findings add to the evidence that, at least in some cases, something that happens in the womb may cause cancer later in life.