Bava Batra 141 - Gifts to Unborn Children
If one whose wife is pregnant says, "If my wife gives birth to a boy, he takes a hundred zuz ($5,000) and if to a girl, she takes two hundred zuz - the infants acquire the money. If she gives birth to a tumtum (a person of indeterminate gender), he does not get anything, but if he is the only child - he inherits all.
So the man prefers a daughter? But we learned that one should leave a son ! Either he realizes that a daughter needs more, or he follows the opinion of Rabbi Yehudah that a daughter is a blessing .
But how can an unborn child acquire a gift? This follows the opinion of Rabbi Yossi that a fetus inherits, and the opinion of Rabbi Yochanan ben Berokah that a will made to the one who inherits is valid .
Art: Henri-François Riesener - Mother and Her Daughter