Pregnancy normally lasts about 40 weeks. A baby born 3 or more weeks early is premature.
When a baby is born too early, he or she may have health problems. Any premature baby can have medical problems. But those who are born before 32 weeks are more likely to have serious problems.
Babies who are premature may not be able to eat, breathe, or stay warm on their own. Their bodies need more time to fully form. After they outgrow the problems caused by being born too soon, most babies can safely go home from the hospital.
WebMD Medical Reference from Healthwise