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A typical pregnancy lasts 40 weeks, but about 10 percent of babies in the U.S. are born preterm (before 37 weeks’ gestation) or premature. Less time in the womb means the infants’ organs are immature and not yet ready to function on their own. Generally, the earlier a preterm birth happens, the more likely it is that complications will occur. Most premature infants, or preemies, spend some time in the hospital in a special nursery called the neonatal intensive care unit, or NICU.

Preterm birth has occurred throughout history, but the issue did not catch the public’s attention until the death of President Kennedy’s son in 1963. Baby Kennedy was only 37 weeks’ gestation and died of respiratory distress. This increased focus on prematurity led to more funding to research ways to treat premature infants. Advances in medical treatment have dramatically increased the survival of preemies since the 1960s. By the 1980s, babies as young as 21 weeks’ gestation were surviving to adulthood.

Prematurity affects every organ system. Complications can be treated more successfully now than in the past. Some common issues include:

• Digestive problems: When the cells lining the digestive tract are immature, babies may develop necrotizing enterocolitis (NEC). NEC is inflammation or infection of the intestine that can cause intestinal tissue to die. Doctors recommend breast milk for premature infants because babies who drink breast milk exclusively have a lower risk of NEC.
• Breathing problems: Immature lungs do not produce a substance called surfactant, which helps the air sacs in the lungs stay open. Without surfactant, preemies may struggle to breathe and go into respiratory distress. Doctors first gave surfactant to premature infants in 1980. Death rates from respiratory distress in premature babies have dropped from over 90 percent in the 1950s to less than 5 percent today.
• Vision problems: When a premature infant is born, their eyes are still developing. Blood vessels in the retina—the light-sensitive tissue in the back of the eye—can grow too much and pull it away from the rest of the eye. The detachment can lead to a type of vision impairment called retinopathy of prematurity (ROP). Doctors discovered that decreasing the concentration of supplemental oxygen given to preemies could actually help decrease the chances of developing ROP.

While treatment for premature infants continues to improve, the cause of preterm birth is still unknown. Doctors have identified some risk factors, including:

• age—women over 35 have a higher risk;
• alcohol or drug use;
• intrauterine infection;
• being pregnant with multiples;
• spacing pregnancies very close together;
• having a previous preterm birth; and
• stress.

Both physicians and patients hope that more research and education will lead to fewer preterm births and improve health outcomes for preemies. November is Prematurity Awareness Month. Read more about ongoing research efforts on the March of Dimes website.

Rebekah Morrow, PhD, is an assistant professor of immunology and microbiology at the Alabama College of Osteopathic Medicine.