Can a babies sex change in the womb?

Answer 1

In a mother's egg, she contributes one X chromosome to her new baby. The father's sperm contains either an X chromosome or a Y chromosome. An XX pairing makes the baby a girl, and an XY pairing makes the baby a boy. Thus, a baby's sex is determined from the moment it becomes a baby.

However, in the beginning stages of growth, it is impossible to tell which sex a baby will be. Structures forming sex-specific reproductive organs are neutral in appearance until late in the baby's growth. This is why men have nipples, even though it is extremely rare for them to develop breast tissue without external hormones. Also, what becomes testicles in males becomes ovaries in females; for males a penis, for women a clitoris; for men a prostate, for women a "G-spot." (To the best of my knowledge, men do not have any sort of "male equivalence" of a womb, which is an exception to the sexual homogeneity of unborn infants.)

So while men and women are distinct genetically from the moment of conception, their bodies go through a stage in which they appear androgynous before the organs fully develop into male and female sex organs.

This is also why it is sometimes difficult for doctors to predict the sex of an unborn child. While penises are more prominent than clitorises, it is possible for a doctor to mistake one for the other when doing an ultrasound. This has given rise to the incorrect notion that babies can change sex while still developing in the womb.