Refusing Babies Treatment?

Tay ❤️
*posting in CC because this might be a sensitive topic for some mothers even though I'm sure most of us will agree*
why is it that doctors will not give any medical treatment to babies born before 22 weeks? I understand that there is a very low chance of the baby surviving but why would they not even try? I believe they should change whatever policy they have and give babies whatever treatment they can rather than just watching them die. I saw a post from a mother on here and her baby was born at 21 weeks and they refused to treat her. She passed away 2 hours later. Who knows whether she would have survived if they had done something