Women who give birth to large infants may have a more than twofold increased risk of developing breast cancer, according to a new study.
Having a large baby may be associated with higher concentrations of certain pregnancy hormones that boost the chances of breast cancer development and progression, the researchers at the University of Texas Medical Branch at Galveston suggested.
How the study was done
The team analysed data from two long-term US studies and found that women who gave birth to the largest babies were 2.5 times more likely to develop breast cancer than those who gave birth to the smallest babies.
The increased risk associated with a baby's weight was independent of the mother's birth weight and traditional breast cancer risk factors, the investigators found.
In addition, the study authors noted, women who gave birth to the largest babies were 25% more likely to have higher concentrations of hormones that affect infant birth weight and breast cancer risk.
What the findings mean
The news from the study, which is published in the journal PLoS One, may help improve prediction and prevention of breast cancer decades before it appears, the researchers said.
"Women can't alter their pregnancy hormones, but can take steps to increase their general protection against breast cancer," study lead author Dr Radek Bukowski, a professor of obstetrics and gynecology, said in a university news release.
Breast-feeding, having more than one child, healthy eating and exercising have been shown to reduce breast cancer risk, Bukowski noted.
The researchers pointed out that while the study found an association between hormonal levels and infant birth weight and maternal breast cancer risk, it did not prove a cause-and-effect relationship. They added that more study is needed.
Warning signs of breast cancer
The U.S. National Cancer Institute has more about breast cancer prevention.
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