What’s wrong referring to the relevant sex characteristics? Why change language for the exceptional and small population? A man who gives birth is still the mother even if they take a social role of a father later in the child’s development.
Because their sex characteristics aren't the relevant thing, the fact that they are pregnant is. The medical field prefers precise terminology. It's only when it comes to trans people that people get weird about it, because they're really using it as an excuse to argue about something else
