Tex. Health and Safety Code § 170.002

(a) Except as provided by Subsection (b), a person may not intentionally or knowingly perform an abortion on a woman who is pregnant with a viable unborn child during the third trimester of the pregnancy.

(b) Subsection (a) does not prohibit a person from performing an abortion if at the time of the abortion the person is a physician and concludes in good faith according to the physician's best medical judgment that:

(1) the fetus is not a viable fetus and the pregnancy is not in the third trimester;

(2) the abortion is necessary to prevent the death or a substantial risk of serious impairment to the physical or mental health of the woman; or

(3) the fetus has a severe and irreversible abnormality, identified by reliable diagnostic procedures.

(c) A physician who performs an abortion that, according to the physician's best medical judgment at the time of the abortion, is to abort a viable unborn child during the third trimester of the pregnancy shall certify in writing to the commission, on a form prescribed by the commission, the medical indications supporting the physician's judgment that the abortion was authorized by Subsection (b)(2) or (3). If the physician certifies the abortion was authorized by Subsection (b)(3), the physician shall certify in writing on the form the fetal abnormality identified by the physician. The certification must be made not later than the 30th day after the date the abortion was performed.