Your baby is developing
Once the sperm has fertilised the egg, your baby is officially developing. Did you know that the sperm determines the sex of your baby at the moment of conception? The mother’s egg carries an X chromosome, while the father’s sperm carries an X or a Y. If the sperm that carries an X fertilises the egg, then the child will be female; if it carries a Y (to make the combination XY), the baby will be male.