Huh?
Nobody at all is suggesting that new-born babies should not be sexed/gendered in the way that they always have been.
The issue is around people who come to realise that the gender they were assigned at birth is not in alignment with their true gender identity.
OK, regardless of which side I look at this from, and I'm sympathetic to both sides, this is so wrong it bothers me. It's a grossly inaccurate use of language.
Doctors do not "gender" babies at birth. At least not on official documents. They "sex" babies at birth.
One of the key components of this discussion has been that sex and gender are no longer considered synonymous. While some debate that change in language usage, this does not give me any problems. Except when the people pushing that change, forget about it when it is convenient for them.
Doctors do not "assign" a gender to a newborn. They make an
observation of sex. There is no observation they can make of that time of gender, as gender is now defined as something akin to a personality trait or self-image. Something internal.
The sex they observe is not "assigned," it is observed. This is no different than the other observations they make at birth: birth weight, number of fingers and toes, etc. It is not an assignation or a judgment, it is an empirical (*) observation.
At birth, the doctor has no way to determine gender. The only thing that is noted on official documents is "sex." (Granted, there may be some forms that use the term "gender," but this is not because they are collecting something different, it's because usage is changing or has changed and the forms do not reflect the change.)
If the doctor does
any gendering at birth, it would be in informing the parents of the sex with the phrase "It's a boy/girl," but that's pretty nit-picky. Knowing the sex, of course, can lead parents to make assumptions about gender. If anyone's assigning a gender at birth, it's parents by choosing clothes and painting the nursery.
But sex, is
not assigned. It is observed and noted. Can that observation be incorrect? Sure. There are a
very few intersex conditions that may result in a misleading phenotype at birth. These are not "mis-assigned." they are erroneous observations due to the absence of data that is not normally needed or collected.
* For those who aren't familiar with the term, "empirical" means:
1 : originating in or based on observation or experience empirical data
2 : relying on experience or observation alone often without due regard for system and theory an empirical basis for the theory
3 : capable of being verified or disproved by observation or experiment empirical laws
4 : of or relating to empiricism
https://www.merriam-webster.com/dictionary/empirical