(CNN) The group that operates an Arizona health care facility where a severely disabled woman was impregnated last year will close the unit, Hacienda HealthCare said Thursday.

"It is simply not sustainable to continue to operate our intermediate care facility for the intellectually disabled," it said.

There are 37 patients at the facility, the company said.

Hacienda said its board voted last week on the change and it has been working with state agencies on a transition plan.