Texas Estates Code - EST § 201.056. Persons Not in Being

(1) considered to be in gestation at the time of the intestate's death if insemination or implantation occurs at or before the time of the intestate's death; and

(2) presumed to be in gestation at the time of the intestate's death if the person is born before the 301st day after the date of the intestate's death.