It’s a healthy discussion, lets take it like that and no need to feel guilty or anything of that sort as i understand what you are trying to say and that you don’t mean any disrespect to the adopted parents.
And i am sure when a women gives birth to a child, its the most special moment hence the significance of it in our religion too :). So nobody can deny that! Let’s pray that every women who is willing for it, gets her chance to experience it. InshaAllah.