I found out at week 20 that I'm expecting triplets, but on the last ul…

I found out at week 20 that I'm expecting triplets, but on the last ultrasound they said the third baby is poorly developing, weight 290g, height 21cm (other two babies weigh 350g, 23cm and 360g, 23cm). I don't know what to do. The doctor says it's better to remove the child, and I don't want them to perform a Cesarean section... But they also say this could cause premature births and other children. I don't know what to do. Maybe someone has had a similar situation? Tell me how it went for you, what did you do?