Study: New mothers may have higher cancer risk

Childbirth ‘protection’ can take about 20 years

Women who recently gave birth might have a higher risk of developing breast cancer, a new study says.

Past research suggests women who have children tend to have a lower breast cancer risk than those who do not. But a research group led by the University of North Carolina Lineberger Comprehensive Cancer Center found that the “protection” from cancer can take more than 20 years after women give birth to take effect.

In an analysis of 15 prospective studies from around the world, the researchers suggest women who have recently had a child are more at risk for breast cancer than their childless counterparts, according to the report published in the peer-reviewed medical journal Annals of Internal Medicine.

In women 55 and younger, breast cancer risk was highest about five years after giving birth, according to the study. The risk for those mothers was 80 percent higher than women who did not give birth. Cancer risk after giving birth was higher for women who had a family history of breast cancer. Childbirth became protective only after 23 years.

Overall, younger women are still less at risk for developing breast cancer than women over 50. Researchers found no increased risk for women who had their first child before age 25.

“This is one piece of evidence that can be considered for building new prediction models. … We want women and their doctors not to assume that recently having a child is always protective for breast cancer,” said Hazel Nichols, a member of the Lineberger Comprehensive Cancer Center who was involved in the study.