A pregnancy that runs its full term lasts 40 weeks, calculated from the start of the mother’s last menstrual cycle. Babies born before the beginning of the 37th week are considered premature. Crucial development continues to occur those last few weeks of pregnancy, including lung growth that ensures adequate breathing and maturation of the digestive system, to ensure proper digestion of nutrients.
Babies born prematurely may face medical and developmental complications but, with time and care, usually grow into happy, healthy children, says Mark R. Mercurio, MD, MA, chief of Yale Medicine Neonatal-Perinatal Medicine.
“Some children born prematurely may have troubles, ranging from mild to severe,” he says. “But most are not going to have severe long-term disabilities. The vast majority of babies born under 28 weeks now leave our unit alive, and most will not have severe long term problems associated with preterm birth.”