A premature baby is one who is born too early, before 37 completed weeks of pregnancy. Premature babies can have more health problems and may need to stay in the hospital longer than babies born later. Nearly half a million babies are born prematurely each year in the United States.
Premature babies may need to stay in the hospital longer or have more health problems than babies born later. Some have to spend time in a hospital’s neonatal intensive care unit (NICU). This is the part of the hospital that takes care of sick newborns.
The earlier in pregnancy a baby is born, the more likely he is to have health problems. But thanks to advances in medical care, even babies born very premature are more likely to survive today than ever before.
Health problems that may affect premature babies include:
- Apnea. This is a pause in breathing for 20 seconds or more. Premature babies sometimes have apnea. It may happen together with a slow heart rate.
- Respiratory distress syndrome (RDS). This is a breathing problem most common in babies born before 34 weeks of pregnancy. Babies with RDS don’t have a protein called surfactant that keeps small air sacs in the lungs from collapsing.
- Intraventricular hemorrhage (IVH). This is bleeding in the brain. It usually happens near the ventricles in the center of the brain. A ventricles is a space in the brain that’s filled with fluid.
- Patent ductus arteriosis (PDA). This is a heart problem that happens in the connection (called the ductus ateriosus) between two major blood vessels near the heart. If the ductus doesn’t close properly after birth, a baby can have breathing problems or heart failure. Heart failure is when the heart can’t pump enough blood.
- Necrotizing enterocolitis (NEC). This is a problem with a baby’s intestines. It can cause feeding problems, a swollen belly and diarrhea. It sometimes happens 2 to 3 weeks after a premature birth.
- Retinopathy of prematurity (ROP). This is an abnormal growth of blood vessels in the eye. ROP can lead to vision loss.
- Jaundice. This is when a baby's eyes and skin look yellow. A baby has jaundice when his liver isn't fully developed or isn't working well.
- Anemia. This is when a baby doesn’t have enough healthy red blood cells to carry oxygen to the rest of the body.
- Bronchopulmonary dysplasia (BPD). This is a lung condition that can develop in premature babies as well as babies who have treatment with a breathing machine. Babies with BPD sometimes develop fluid in the lungs, scarring and lung damage.
- Infections. Premature babies often have trouble fighting off germs because their immune systems are not fully formed. Infections that may affect a premature baby include pneumonia, a lung infection; sepsis, a blood infection; and meningitis, an infection in the fluid around the brain and spinal cord.
Premature babies sometimes face health problems throughout their life, including:
- Autism, a group of disorders that affect a child’s speech, social skills and behavior
- Intellectual disabilities
- Cerebral palsy, a group of conditions that affect movement, balance and posture
- Lung problems
- Vision and hearing loss
Talk to your baby’s health care providers about any health conditions your baby has. He may be healthy enough to go home soon after birth, or he may need to stay in the NICU for special care. Your baby can probably go home from the hospital when he:
- Weighs at least 4 pounds
- Can keep warm on his own, without the help of an incubator. An incubator is an enclosed unit that helps premature babies stay warm.
- Can breastfeed or bottle-feed
- Gains weight steadily (1/2 to 1 ounce each day)
- Can breathe on his own
Your baby may need special equipment, treatment or medicine after he leaves the hospital. Your baby’s provider and the staff at the hospital can help you with these things and teach you how to take care of your baby. They also can help you find parent support groups and other resources in your area that may be able to help you care for your baby.
Last reviewed September 2012
See also: Babies born 3 to 6 weeks early, The premature infant: how old is my baby?, Understanding your premature infant, The NICU experience, Preterm labor and birth, March of Dimes Prematurity Campaign, The NICU Family Support program
Most common questions
How do I calculate adjusted age for preemies?
Chronological age is the age of a baby from the day of birth. Adjusted age is the age of the baby based on his due date. To calculate adjusted age, take your baby's chronological age (for example, 20 weeks) and subtract the number of weeks premature the baby was (6 weeks). This baby's adjusted age (20 - 6) is 14 weeks. Health care providers may use this age when they evaluate the baby's growth and development. Most premature babies catch up to their peers developmentally in 2 to 3 years. After that, differences in size or development are most likely due to individual differences, rather than to premature birth. Some very small babies take longer to catch up.
What does it mean if a baby is born “late preterm?”
Late preterm means that a baby is born after 34 weeks but before 37 weeks of pregnancy. It's important to try to have your baby as close to 39 weeks of pregnancy as possible. In the last few weeks of pregnancy, your baby's organs, like his brains, lungs and liver, are still growing. Waiting until you're at least 39 weeks also gives your baby time to gain more weight and makes him less likely to have vision and hearing problems after birth. Your baby will also be better able to suck and swallow and stay awake long enough to eat after he's born. Babies born early sometimes can't do these things.