Sec. 171.042. DEFINITIONS. In this subchapter: (1) "Post-fertilization age" means the age of the unborn child as calculated from the fusion of a human spermatozoon with a human ovum. (2) "Severe fetal abnormality" has the meaning assigned by Section 285.202. Added by Acts 2013, 83rd Leg., 2nd C.S., Ch. 1, Sec. 3, eff. October 29, 2013.