Birth Size May be Linked to Breast Cancer

Recent studies suggest that what happens in the womb may cause cancer later in life, particularly in larger women who give birth to longer babies. Further research, published in the Public Library of Science journal PloS Medicine, indicates links between birth size and breast cancer.

According to the American Cancer Society, breast cancer is the leading cause of cancer deaths among women worldwide. The organization estimates about 465,000 women died of breast cancer globally in 2007, and 1.3 million new cases were diagnosed.

Declining death rates from breast cancer in developed countries are also attributed to early detection through mammography screening.

The research was comprised of 32 studies of more than 600,000 women, mainly in developed countries. The analysis included more than 22,000 women who had breast cancer. The researchers also found a strong correlation with birth size, birth length, and head circumference, with birth length demonstrating the strongest link. Women with recorded birth weights of 4 kilograms or more had a 12 percent higher chance of breast cancer than babies weighing 3 to 3.5 kilograms at birth. They also estimated that birth size may be responsible for up to 5 percent of all breast cancers in women up to the age of 80.

Partially responsible for the link are estrogen and human growth hormone, which further exacerbate the prevalence of the disease. Only further research can determine the extent of the incidence.