Women at average risk for breast cancer should begin mammogram screening at age 40 instead of 50, according to updated guidelines issued earlier this year by the U.S. Preventive Services Task Force (USPSTF).

Previous guidelines were issued in 2016. Since then, the task force has reviewed more current medical data. It gave the updated recommendation a B grade, meaning there is “high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial.” USPSTF recommendations carry weight because the Affordable Care Act (ACA, or Obamacare) requires health insurance plans to cover preventive health care services that have received an A or B grade from the task force.

The updated guidelines spurred an ongoing discussion about whether too much breast cancer screening can be detrimental, especially because screening people at low risk may lead to false positives, unneeded biopsies and unnecessary treatment of slow-growing tumors that would have remained harmless—not to mention extra costs, time and anxiety.

A study published this summer in the Annals of Internal Medicine makes the case for educating women about the pros and cons of breast cancer screening instead of recommending that all women get mammograms starting at age 40.

The study, which included women ages 39 to 49, found that when participants were informed of the potential benefits and harms of mammograms, many preferred to delay screening. At first, only 8% of the women surveyed said they wanted to wait until they turned 50 to get a mammogram, but once they were informed of the nuances of screening, 18% said they preferred to wait until age 50.

“They had rational, logical reasons for their preferences,” lead author of the study, Laura Scherer, PhD, a social psychologist at the University of Colorado School of Medicine, told STAT News. “Women who wanted to screen earlier, they had higher risk, like a family history, and were less concerned about the downsides.”