A fetus born at 5 months gestation is not capable of surviving outside the womb according to the American Pregnancy Association. In order to be considered viable and have a chance at survival, a fetus must be at least 24 weeks old.
The earliest born fetus that survived was born at 21 weeks and 5 days gestation, a figure equal to approximately 6 months of pregnancy. A fetus born before 24 weeks of pregnancy has a low chance of survival, and those that do survive often suffer from some type of disability.
Doctors do try to save some babies that are born before 24 weeks of pregnancy, depending on the baby's condition and weight. Some require a baby younger than 24 weeks gestation to be a minimum of 1 pound in weight for the baby to receive medical care to prolong his or her life.