U.S. Sens. Brian Schatz and Mazie Hirono joined 37 fellow Democratic senators Tuesday in prodding the Obama administration to take a stronger stance to ensure the Affordable Care Act’s birth-control mandate is being followed.

In a letter to Sylvia Burwell, the secretary of the U.S. Department of Health and Human Services, the senators voiced their concerns over findings in a pair of studies that insurers are providing women inaccurate information about the required birth-control coverage.

Senators Brian Schatz and Mazie Hirono.

Courtesy of Sen. Mazie Hirono

The standards issued in 2011 require health insurers to cover all government-approved contraceptives for women, without co-payments or other charges. Insurers are also mandated to provide the coverage for sterilization procedures and “patient education and counseling for all women with reproductive capacity.”

“In the 21st century, women should have access to affordable, comprehensive healthcare services, like birth control, that empower them to make their own healthcare decisions and provide economic security for their families,” the Senators wrote. “Unfortunately, we write with serious concerns that some insurers are failing to uphold the standards set in the Affordable Care Act and as a result leaving women without the health care services they are entitled to under the law.”

The senators are asking Burwell to issue a new written guidance to make sure that insurers comply with the contraceptive mandate. They are also calling for consumer education efforts and a push for the states to develop their “plan of action” for proper enforcement.