Mont. Code Ann. § 33-22-1906

A health benefit plan may not deny payment for covered services provided to a covered person under 33-22-1903 and 33-22-1904 by a certified advanced practice registered nurse practicing in collaboration with the participating obstetrician or gynecologist. This section may not be construed to expand the definitions of participating obstetrician or gynecologist or primary care physician in 33-22-1902 to include certified advanced practice registered nurses.