A premature baby is one that is born before 37 weeks’ gestation (the length of a pregnancy from conception to birth). The normal period of gestation in humans is 40 weeks. If your baby is premature, it may need to be cared for in a specialised unit, called a neonatal unit, until his or her internal systems are more fully developed. The length of time your baby will stay in the neonatal unit will generally depend on how early it was born.