https://www.whitehouse.gov/presidential-actions/2025/01/defending-women-from-gender-ideology- extremism-and-restoring-biological-truth-to-the-federal-government/
(d) Female means a person belonging, at conception, to the sex that produces the large reproductive cell.
(e) Male means a person belonging, at conception, to the sex that produces the small reproductive cell.
https://www.ncbi.nlm.nih.gov/books/NBK222286/
All human individualswhether they have an XX, an XY, or an atypical sex chromosome combinationbegin development from the same starting point. During early development the gonads of the fetus remain undifferentiated; that is, all fetal genitalia are the same and are phenotypically female. After approximately 6 to 7 weeks of gestation, however, the expression of a gene on the Y chromosome induces changes that result in the development of the testes
Fetuses are female until the Y chromosome begins to express about two months into development... but this executive order defines sex from conception.