A "Premature Birth" is defined as a birth that occurs before the 37th week of pregnancy.
Survival Rates:
Babies born at 23 weeks have a 17% chance of survival.
Babies born at 24 weeks have a 39% chance of survival.
Babies born at 25 weeks have a 50% chance of survival.
From 31-36 weeks, almost is about 95-100% of babies are able to survive with the help of medical technology.
I would say anywhere from 26 to 36 weeks would be the range of higher percentage at which the infant would have a better chance of survival with medical treatment.
-Medical Student (College Level)