There are two chromosomal human genders: male and female. You are female if you are born with a vagina and male if you are born with a penis. If you were born with a penis, only extensive surgery and intensive hormone treatment can make you appear to be female. And if you are female and want to become a male, the surgery is more extensive. The point is you are what you were born as and just deciding you are a member of the opposite sex doesn’t make you one.
Human females are the ones meant to give birth. Males have not been designed to get pregnant and give birth. A male that gets pregnant would be the result of a genetic fluke or of surgical intervention. Nature meant for the female of the human species to be the one who becomes pregnant, carries the developing child, and gives birth.