It is unconstitutional for the government to single out businesses for "unequal" treatment - unless the same standard applies to fertility clinics (invitro), plastic surgeons and other similar style clinics. 

Not only does it violate the Equal Protection Clause of the U.S. Constitution but also the Supremacy Clause (Article VI, section 2) that essentially states that the U.S. Constitution (as interpreted by the U.S. Supreme Court) is the "Supreme Law of the Land" for the entire United States (local, state, federal).  In the Supreme Court case of "Roe v. Wade" the board is duty-bound to follow the law. 

In section 3 of Article VI, each and every board member has sworn (or affirmed) to upold the "Supreme Law of the Land" as a condition of holding public office. If board members want to remain on the board they have a duty to honor their oath of office.