What Is a Premature Baby?

Medically Reviewed by Poonam Sachdev on October 03, 2022
10 min read

Doctors call a baby "premature" if they're born more than 3 weeks before the due date. If your baby is a preemie, you'll have plenty of questions about how to give them the extra care they need. Since preemies haven't had as long to develop inside the womb, some may have health problems and need to stay in the hospital longer than babies born on time. A lot depends on how many weeks before your due date your baby is born. The earlier the birth, the more complications an infant is likely to have.


Doctors divide preemies into groups depending on how old they are at birth:

  • Late preterm: Between 34 weeks and 37 weeks
  • Moderately preterm: Between 32 and 34 weeks
  • Very preterm: Between 28 and 32 weeks
  • Extremely preterm: 28 weeks or less

At first, your baby may look different from other newborns you've seen:

  • Premature babies are smaller than those born closer to their due date, with less fat.
  • Your baby's head might look a little large for their body.
  • Their skin might seem thin, and it could be covered in a fine hair called lanugo.
  • Their features may look less rounded than those of full-term babies.

You may notice some other differences, too:

  • Your preemie may cry softly or not at all, at first, since their breathing system isn't fully developed. They may also have breathing problems.
  • They may have trouble feeding because they don't have reflexes for sucking and swallowing.
  • Your baby's temperature might be low, since they don't have much body fat to keep them warm.

As the baby grows and gains weight, they'll start to look and act more like other infants.

Doctors don't always know why a baby is born prematurely. But you may be more likely to have a premature baby if you:

  • Are expecting twins or other multiples
  • Had a preemie before
  • Have problems with your uterus, cervix, or placenta
  • Are under 17 or over 35
  • Were underweight or overweight before pregnancy
  • Smoke or use illegal drugs
  • Conceived with in vitro fertilization
  • Have had multiple miscarriages or abortions
  • Got pregnant less than 6 months after an earlier pregnancy
  • Have a health condition like diabetes or high blood pressure
  • Had an infection or injury during pregnancy
  • Went through a stressful situation, like the death of a loved one

There's no foolproof way to prevent a preterm delivery. But if you're planning a pregnancy, take these steps to stay healthy:

  • Wait at least 18 months between pregnancies.
  • Maintain a healthy weight.
  • Don’t smoke, drink, or use drugs.
  • Start seeing a doctor for prenatal care as soon as you think you're pregnant.
  • Get treatment for any health conditions you have.
  • Get any vaccines you need, and take care to avoid infections.
  • Try to reduce your stress levels.
  • If you have depression, get treatment for it.

If you're pregnant and at high risk of preterm labor, your doctor may give you:

  • Progesterone supplements. This hormone may help if you have cervical problems or a history of premature births.
  • An operation called cervical cerclage. If you have a "short" cervix, your doctor can stitch it closed to help support your uterus. They'll remove the stitches when you're ready to give birth.

Premature babies are at risk of complications because their organs didn't have as much time to develop in the womb. When babies are born very prematurely, they are at higher risk for some health problems.

Some short-term issues that can happen are:

Loss of body heat. Lack of body fat makes preemies likely to lose body heat quickly. If their temperature gets too low, they can have breathing problems and low blood sugar.

Breathing problems. Some preemies have apnea, long pauses in their breathing. Another condition, called respiratory distress syndrome, happens when your baby's lungs don't make enough of a liquid called surfactant. If this happens, doctors will treat the baby with an artificial version of the liquid, which helps the lungs expand. They may need to put the baby on a ventilator.

If your baby is on a ventilator, there is a chance that the high oxygen levels and pressure inside it can damage the tiny air sacs in their lungs. This is called bronchopulmonary dysplasia. If this happens, your baby will need oxygen for several weeks or months. Preemies often outgrow this as their lungs mature.

Heart problems. Patent ductus arteriosus is when your baby has an opening between two major blood vessels leading from their heart. It often closes on its own. Preemies also may have low blood pressure. That could mean they need IV fluids, medicines, or maybe a blood transfusion.

Brain problems. Very early birth makes a baby more likely to have bleeding in the brain, called intraventricular hemorrhage. These often go away without doing much harm.

Digestive problems. After they start feeding, some preemies can get a condition called necrotizing enterocolitis. It happens when tissues in their intestines get inflamed. The risk is lower in babies who are only breastfed.

Blood problems. Anemia, in which your baby's body doesn't make enough red blood cells, can keep your baby from gaining weight and being active. Doctors treat it with iron supplements, medicine, or blood transfusions.

When your baby has jaundice, their skin turns a yellowish color. It happens because a chemical called bilirubin builds up in their blood. Your baby may need treatment with special lights.

Possible long-term complications include:

Vision problems. Retinopathy of prematurity happens when the baby's retina – a layer of nerve cells at the back of the eye that senses light – isn't fully developed. It can lead to scars on the retina. In rare cases, the retina can get detached.

Hearing problems. Preemies are at increased risk for hearing loss. They are usually tested in the neonatal nursery. Your pediatrician can follow up with care.

Dental problems. Preemies may teethe late, or have teeth that are discolored or not aligned properly.

Cerebral palsy. This is a disability that affects movement and muscle tone. While most people who have it were not born prematurely, premature birth is a risk factor. Occupational and physical therapy can help babies and kids who have cerebral palsy.

Learning and behavior problems. Premature babies are often slower to hit development milestones than full-term infants. They may have learning disabilities and behavior issues later on. Talk to your doctor if you're concerned.

Other health problems. Preemies are more likely to end up with long-lasting conditions like infections, asthma, and problems with feeding.

How early they were born. In general, the earlier your baby was born, the more likely they are to have lasting problems that affect their growth and development.

Late preterm babies tend to catch up to full-term babies quickly. Babies who were born earlier than that may develop more slowly and have setbacks. Extremely preterm babies are more likely to have serious, lasting disabilities.

Birth weight. The less your baby weighed when they were born, the more likely they are to have health problems that could affect how they grow.

Whether they have other health conditions. Preemies are more likely to have medical issues like infections or heart, lung, or intestinal conditions. Doctors can treat these problems, and some go away as your baby gets older. They may still slow down your child's growth and development. Your baby may need extra time to build up their strength.

How complicated treatment was in the hospital. If your baby spent a long time in the neonatal intensive care unit (NICU) and needed a lot of special care, they are likely to need extra time to develop.

Premature babies get extra care as soon as they're born. Your baby may need to see a neonatologist, a pediatrician who treats preemies.

Your doctor may suggest your baby get special care in a neonatal intensive care unit (NICU). NICU staff may use several devices or machines as they help you take care of your baby. Each piece of equipment plays an important role in getting an infant ready to go home.

For example, nurses may place your baby in an incubator, a plastic bassinet that keeps them warm. They may put sensors on their body to keep tabs on their heart rate, blood pressure, and temperature.

Your preemie may also need a machine called a ventilator to help them breathe. They could get fluids and nutrients through an IV. Nurses may put a feeding tube into your baby's nose to feed them breast milk or formula.

Even though your little one is in the NICU, you'll still get your chance to bond. Once your doctor gives the OK, you'll be able to touch, hold, and breastfeed or bottle-feed your baby. You may be encouraged to pump breast milk until your baby learns to nurse to help them grow and fight infection.  

Many NICUs have moms and dads give skin-to-skin care for preemies. You may hear them call it kangaroo care. You place your infant against your bare chest, which helps them stay warm, breathe easier, and sleep more deeply. Some babies nap on their parents' skin. Others simply enjoy the close contact.

Not all premature babies have complications. And for those who do, today's advanced medical care means babies born very early are more likely to survive – and thrive – than ever before.

How long until your baby goes home varies. It could be a few days or weeks after birth.

Your baby's doctor will clear them to head home once your baby:

  • Breathes on their own
  • Can breastfeed or bottle-feed
  • Weighs at least 4 pounds
  • Gains weight steadily
  • Stays warm without help

Your baby might need special equipment even once they're settled in at home. Some babies use monitors, like those for sleep apnea, or continue to get oxygen. No matter what your baby needs, your nurses and doctors will teach you how to use the equipment before you leave. They should train you in infant CPR, too. And remember to get your baby any vaccines that the doctor recommends before leaving the hospital.

Taking care of your preemie will likely take up much of your time and attention, but don't forget to take care of yourself, too. Get rest, eat healthy food, and accept help from friends and family.

It's normal to feel like you're on an emotional roller coaster. Think about joining a support group where you can talk to other parents who are going through the same things you are. You can also meet with a counselor to discuss the challenges you face.

Doctors and parents track development by noting when babies learn key skills, like smiling, rolling over, or crawling. You and your doctor can compare this with the average age that babies reach these milestones.

Keep in mind that the ages that babies are supposed to meet milestones are always rough estimates, even for full-term babies. And when you're looking at a chart of developmental milestones, you need to use your baby's "corrected age" – also called adjusted age – instead of their actual age. Your baby's corrected age is based on your due date – the age your baby would be if they had been born full-term.

If you want to do the math yourself, subtract the number of weeks they were born early from their current age. For example, if your baby is 18 weeks old but was born 8 weeks early, their corrected age would be 10 weeks.

If you want to keep tabs on your preemie's development, always use your baby's corrected age for milestones at least until age 2 or so. Around then, most preemies have caught up, so it's usually OK to use their real age instead.

Watching your baby develop and grow over the next 2 years is going to be exciting – and maybe a bit stressful too. Follow some simple tips that can keep you from getting overanxious.

Remember that preemies are different from full-term babies. Your baby may be fussier and not respond to you in the same way as a full-term baby. They may have more trouble sleeping through the night. Most preemies grow out of these problems during their first year.

Don't worry too much about milestones. No baby – whether they're full-term or premature – develops on an exact schedule. If your child doesn't meet a milestone right on time, it's not usually something to worry about. If you have concerns, discuss them with your pediatrician. They can validate your concerns and discuss strategies to promote your baby's development.

Focus more on progress than specific targets. Don't get hung up on the exact age your baby reaches this or that milestone. Look at the advances they make instead. All babies babble before they say their first word. They'll stand before they can walk. For the first 6 months, they gain about 1 pound per month. As long as your baby is moving forward in their development, that's what's important.

Keep your own notes. While your doctor will be paying close attention to your baby's growth, it's smart to keep your own written records. It's a good way to catch anything unusual early. You'll also like being able to look back and see how far you've come.

Team up with your child's medical team. Preemies need extra care, especially in their first few years. The best way to make sure your baby is on track is to keep regular appointments with your child's doctor and other specialists. They can catch any issues as they develop, so your baby can get the care they need.

Get help if you need it. Talk to your child's doctor about a state program called Early Intervention. It offers special services to help babies and toddlers (up to age 3) with a higher risk of developmental delays or disabilities. Ask your doctor if there is a need for speech therapy, physical therapy, or occupational therapy.