Sex determination in an unborn baby is determined by the combination of sex chromosomes inherited from the parents.

Typically, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). During fertilization, danh bom lieu chet the father’s sperm can contribute either an X or a Y chromosome, determining the genetic sex of the offspring. This process occurs at the moment of conception and is responsible for the development of the baby’s sex characteristics.