Noadiah the prophetess (Nehemiah 6:14) was a false prophet hired against Nehemiah — she should not be used to establish frequency of female prophets.

Nehemiah 6:14 mentions Noadiah as a prophetess, but she was a false prophet hired to intimidate Nehemiah and oppose his reforms. Some use her to establish frequency of female prophets, but including false prophets in that count is problematic since that represents the enemy's work, not God's calling.