Updated

Over one-third of women in the United States have limited or no access to medical centers that treat fertility problems, according to a new study.

After examining data from the Centers for Disease Control and Prevention (CDC), researchers found fertility centers are mainly located in heavily populated areas in the U.S.

"About 40 percent of women between age 20 and 50 are living in areas where there are either limited or no options for them," said Dr. John Harris, of the University of Pittsburgh's School of Medicine and Magee-Womens Hospital of UPMC.

Harris and his colleagues write in Fertility and Sterility that lack of geographic access to assisted reproductive technology (ART) is common and a significant obstacle for patients with infertility.

Using census data and information from the CDC, the researchers evaluated geographic access to ART clinics in the U.S. - where, they say, an estimated 7.5 million women face difficulty in having children.

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They identified a total of 510 ART clinics in 144 census areas, which are geographic regions drawn by similarities to nearby urban centers.

Overall, clinics tended to cluster near population centers like Boston, Los Angeles, New York and Philadelphia. About 60 percent of women ages 20 to 49 lived in areas with multiple ART clinics.

About 29 percent lived in areas with no clinics, however. Another 11 percent of women in that age group lived in areas with only one clinic, which means they didn't have a choice of providers.

In addition to geographic obstacles, cost is also a significant burden since people often pay for fertility treatments out of pocket, Harris said.

Long distances to ART clinics means more costs for travel, lodging and days off work.

"There is already a significant cost burden," he said. "Whenever you increase the cost, that only increases the barriers."

The expenses can add up, because in vitro fertilization may require several repeat visits to ART clinics over a short period, according to Dr. Kara Goldman, a reproductive endocrinologist and assistant professor at NYU Langone Medical Center's Fertility Center in New York.

"This helps to demonstrate the geographic barriers are significant for patients," said Goldman, who wasn't involved in the new study. "This is something we have to address in our field."

Harris said large medical centers can help by operating satellite ART clinics. Business and employers can also help by allowing people additional time off for fertility treatments.