A new study conducted by researchers at National Institutes of Health has found that the risk of breast cancer in women taking fertility drugs goes up when they get pregnant.
There have been a number of studies looking into whether fertility drugs play a role in reducing or increasing the risk of breast cancer in women and the conclusions have been mixed with some studies claiming that they do increase the risk and some claiming that they reduce the risk.
Researchers at NIH observed 1,400 women diagnosed with breast cancer before the age of 50 years and compared them with 1,600 of their sisters who had no signs of the disease. Around 288 participants admitted to taking ovulation-stimulating fertility drugs, 141 of whom had pregnancy lasting 10 weeks or more after taking the drugs.
The researchers found that those who took the fertility drugs and did not get pregnant had a lower risk of being diagnosed with breast cancer under 50 years of age compared to those who got pregnant. "Our data suggest that exposure to a stimulated pregnancy is enough to undo the reduction in [breast cancer] risk associated with a history of exposure to ovulation-stimulating drugs", the researchers wrote in the report, published in the Journal of the National Cancer Institute.