A bill advancing through the Texas Legislature could drastically decrease the number of legal abortion facilities in the state.

Supporters of Senate Bill 537, which would increase regulations for abortion facilities, say it will improve women’s safety. But abortion rights advocates say that the bill is a thinly veiled effort to close 37 of the state’s 42 abortion facilities, and that it would reduce women’s access to legal abortion.

“I understand the suspicion, but this really is about improving health care for women getting abortions,” said the bill’s author, State Senator Bob Deuell, a Republican from Greenville who is a primary care physician.

The bill would require abortions, including those induced by drugs, to be performed in so-called ambulatory surgical centers. The regulations for such facilities include specific sizes for rooms and doorways, and additional infrastructure like pipelines for general anesthesia and large sterilization equipment.