Often, the exact cause of a preterm birth isn't clear. Many things can raise the risk though. These include being pregnant with more than one baby, or having had a previous preterm birth. Long-term health problems such as diabetes also can raise the risk. Unhealthy choices such as smoking cigarettes or using illegal drugs can be risk factors, too.

Some preterm babies have mild symptoms, such as being smaller in size or having less-rounded features than full-term infants. Other preterm babies have major health problems, such as trouble breathing, heart defects or bleeding in the brain. The earlier a baby is born, the higher the risk of serious health problems.

Preterm babies get treatment in a special nursery department at the hospital. They often receive help to feed and stay warm. Infants with more-serious health problems may need medicines or surgery. A team of health care professionals closely tracks the health of preterm babies. Parents can ask the team what their baby's care plan will be.