Creating user and profile with single rest_framework endpoint

I have a task that involves creating a doctor user endpoint, the basic user auth fields and doctor specific profile info has to be provided during signup.
In the 6 chapter of Django series part 2, a similar serializer was used but no explanation on how to create views for the particular scenario.

class UserCreateSerializer(BaseUserCreateSerializer): 
    birth_date = serializers.DateField(read_only=True)

    class Meta (BaseUserCreateSerializer.Meta): 
        fields = ['id', 'username', 'password', 'email', 'first_name', 'last_name', 'birth_date']

In the above scenario how do I save birth_date to the user profile after the user has been created.