Hello, I want to ask: has anyone had a baby that was small in the womb…

Hello, I want to ask: has anyone had a baby that was small in the womb? My gestational age by my dates is 33 weeks 6 days, but by ultrasound it's 25 weeks 6 days, and the fetal weight is about 850 grams. They said if there is a heartbeat on Sunday they will do a cesarean section. Right now I'm on injections to help mature the lungs. Has anyone had this or knows someone who has? Please advise.