According to the National Institute of Child Health and Human Development, about 12 percent of all births in the United States are premature, taking place before the 37th week of gestation. Premature birth can lead to numerous complications. The severity of these problems is often determined by how far along the pregnancy had progressed before delivery.
Low Birth Weight
Premature babies are smaller than babies born at full term. Low birth weight is typically defined as weighing under 5 1/2 lbs. Some premature babies born extremely early weigh less than 2 lbs. at birth.
Lung Problems
The lungs of a fetus do not complete their development until the end of pregnancy, so babies born prematurely start their lives with immature lung function. Respiratory distress syndrome is a severe complication resulting from immature lungs that don't make the protein required to keep air sacs inflated. It is more common in infants born before the 34th week of gestation, according to the March of Dimes. For premature babies who are placed on supplemental oxygen for long time periods, chronic lung problems similar to asthma may continue for the rest of their lives.
Apnea
While full-term babies sometimes experience short periods during which their breathing stops, this is generally less than 10 seconds at a time. Premature babies may experience apnea of 20 seconds or more.
Intracranial Hemorrhage
Bleeding in the brain, a condition known as intracranial or intraventricular hemorrhage, occurs in some premature babies. This condition is generally seen only in babies born earlier than 32 weeks. Intracranial hemorrhage can be mild or severe. Severe cases may result in permanent brain damage.
Heart Problems
The blood flow in the heart changes immediately after birth, and some premature babies may have difficulty making this transition. Patent ductus arteriosus (PDA) is a condition in which the duct that causes blood to bypass the lungs in a fetus does not close. PDA can lead to heart failure.
Intestinal Problems
Because a premature baby has an immature digestive system, he may have difficulty digesting food properly. A severe intestinal disorder called necrotizing enterocolitis (NEC) may develop three to four weeks after birth in some premature babies.
Vision Loss
Premature babies may experience a loss of vision. This can occur if the blood vessels in the eye begin to grow abnormally, cutting off proper blood flow to the retina.
Jaundice
Babies born prematurely can develop jaundice, a yellowing of the skin and eyes. This happens if the liver of a premature infant is unable to properly process bilirubin, a waste product found in blood.
Infectious Diseases
Because premature babies have immune systems that are not fully developed, they are more susceptible to infections than peers of normal gestation. Pneumonia, meningitis and sepsis are common infections experienced by premature infants.
