(a) The prohibitions and requirements under Sections 171.043, 171.044, and 171.045(b) do not apply to an abortion performed if, in the physician's reasonable medical judgment, the abortion is necessary due to a medical emergency and necessitates, as applicable:
(1) the immediate abortion of her pregnancy without the delay necessary to determine the probable post-fertilization age of the unborn child;
(2) the abortion of her pregnancy even though the post-fertilization age of the unborn child is 20 or more weeks; or
(3) the use of a method of abortion other than a method described by Section 171.045(b).
(b) A physician may not take an action authorized under Subsection (a) if the medical emergency arises from a claim or diagnosis that the woman will engage in conduct that may result in her death or in substantial and irreversible physical impairment of a major bodily function.
(c) The prohibitions and requirements under Sections 171.043, 171.044, and 171.045(b) do not apply to an abortion performed on an unborn child who has a severe fetal abnormality.