Half of women who are recommended to get an annual mammogram do so, even if they have insurance to pay for the procedure, according to a new study.

The results showed that 50 percent of women ages 40 to 85 had a mammogram in a given year, and 60 percent had two or more mammograms over the four-year study period.

Average annual mammography rates were 47 percent for women ages 40 to 49, 54 percent for women ages 50 to 64, and 45 percent for women ages 65 and older, according to the study.

The study was based on medical claims in a database of more than 12 million people, submitted between January 2006 and December 2009. All claims the researchers reviewed were from women had either employer-provided insurance or Medicare.

Researchers did not examine reasons why women were not getting mammograms, said study researcher Dr. Milayna Subar, vice president and national practice leader for oncology at Medco Health Solutions, Inc. in New Jersey, a health care and pharmaceutical services company. But some possible reasons include fear of discomfort from the test, lack of available screening centers and denial.

Last year, the U.S. Preventive Services Task Force, an independent panel of non-federal experts in prevention and evidence-based medicine, recommended that the age of first mammogram be raised from 40 to 50.

"Women reacted strongly to that recommendation, with protests about their right to have an annual mammogram that should not be taken away," Subar said in a statement.

"Interestingly though, we found that a large percentage of women do not get regular mammograms," she said.

Other groups, such as the American Cancer Society, still recommend yearly mammograms starting at age 40.

Previous studies have highlighted the importance of getting mammograms to screen for breast cancer. One study, published last month in the journal Radiology, found that women who started getting mammograms at age 40 could reduce their risk of dying from breast cancer by 24 percent compared with women who don't get mammograms.

The new research was presented today (Dec. 9) at the 33rd annual San Antonio Breast Cancer Symposium.

Pass it on: Half of women don't get recommended mammograms to screen for breast cancer, even if they have health insurance.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.