Premature Baby

When a baby arrives before completing 37 weeks in the womb, they need special attention and care to grow and thrive. These tiny fighters face unique challenges, but with modern medical care and dedicated support, most can overcome early obstacles and develop into healthy children.

Table of contents

• What is a premature baby?
• Why are babies born premature?
• How common is premature birth?
• How premature babies look and act
• Health challenges and complications
• Special care and treatment
• Feeding premature babies
• Going home and ongoing care
• Reducing the risk of premature birth

What is a premature baby?

A premature baby, also called a preterm baby or “preemie,” is a baby born too early, before 37 completed weeks of pregnancy.^[1] A typical pregnancy lasts about 40 weeks, so premature babies are born at least three weeks before their expected due date.^[2]

Doctors group premature births into different categories based on when the baby is born. These groupings help medical teams understand what kind of special care each baby might need.^[1]

The categories are:

• Late preterm: babies born between 34 and 36 completed weeks of pregnancy. Most premature births happen during this time.^[2]
• Moderately preterm: babies born between 32 and 34 weeks of pregnancy.^[1]
• Very preterm: babies born before 32 weeks of pregnancy.^[2]
• Extremely preterm: babies born before 25 to 28 weeks of pregnancy.^[1]

The earlier a baby is born, the higher the chance of health problems. Babies born before 23 weeks probably will not survive.^[5] However, thanks to medical advances, children born after 28 weeks of pregnancy and weighing more than 2 pounds 3 ounces have almost a full chance of survival. Eight out of ten babies born after the 30th week have minimal long-term health or developmental problems.^[3]

Why are babies born premature?

Most of the time, doctors don’t know the exact reason why a baby is born too early.^[5] Preterm birth can happen for many reasons. Most premature births happen spontaneously, but some are due to medical reasons that require the baby to be delivered early.^[4]

Some health conditions during pregnancy can lead to premature birth. These include gestational diabetes (high blood sugar during pregnancy), hypertension (high blood pressure), heart or kidney problems, and infections of the amniotic membranes or vaginal or urinary tracts.^[10] Problems with the placenta (the organ that nourishes the baby in the womb), such as placenta previa or placental abruption, can also cause early delivery.^[2]

Other factors that may contribute to premature birth include carrying twins, triplets or more babies, problems with the shape of the uterus, smoking cigarettes, using drugs or drinking alcohol during pregnancy, being underweight before pregnancy, and not getting good prenatal care.^[5]

Women are at higher risk of having a premature baby if they are Black or Hispanic, are expecting multiples, are under age 17 or over age 35, have had a previous preterm birth, smoke or use substances while pregnant, or don’t gain enough weight during pregnancy.^[2]

How common is premature birth?

About 1 out of every 10 babies in the United States is born premature.^[2] Globally, an estimated 13.4 million babies were born preterm in 2020, which is more than 1 in 10 babies.^[4]

Premature birth occurs in about 11 to 13 percent of pregnancies in the United States. Almost 60 percent of twins, triplets and other multiple deliveries result in preterm births.^[3] Rates of premature birth are increasing as more women become pregnant after age 35 and as assisted reproductive technologies like IVF more often result in multiple pregnancies.^[2]

Preterm birth complications are the leading cause of death among children under 5 years of age, responsible for approximately 900,000 deaths in 2019. However, three-quarters of these deaths could be prevented with current, cost-effective care.^[4]

How premature babies look and act

Premature babies look and act different from full-term babies. The earlier a baby arrives, the more noticeable these differences are. As premature babies grow and get closer to what would have been their full-term age, they start to look and act more like typical newborns.^[6]

Premature babies are usually much smaller than full-term babies. While the average full-term baby weighs about 7 pounds at birth, a premature newborn might weigh 5 pounds or even considerably less. Many preemies are considered low birth weight, weighing less than 5 and a half pounds.^[3]

Physical features that premature babies often share include:

• Small size with a head that looks large compared to the rest of the body^[1]
• Sharp, less rounded features due to lack of fat cells under the skin^[1]
• Thin, shiny, pink or red skin that may be transparent-looking, allowing you to see veins beneath it^[5]
• Little body fat and little or no hair on the head^[1]
• Fine body hair called lanugo on the back and shoulders^[3]
• Eyelids that may stay closed until about 30 weeks of age^[6]
• Genitals that are small and not yet fully developed^[6]

Premature babies often behave differently than full-term babies. They may sleep more than other newborns but don’t sleep for very long each time.^[10] Their cry may be weak-sounding, and they may have trouble staying awake for feeding.^[6]

Common behaviors in premature babies include breathing quickly with pauses for seconds at a time (called apnea), having trouble keeping their body temperature stable, and difficulty coordinating sucking, swallowing and breathing during feeding.^[5]

Health challenges and complications

Premature babies face health challenges because their organs didn’t have enough time to fully develop before birth. The earlier they are born, the more complications they tend to have.^[5] These babies often need care in a neonatal intensive care unit or NICU, which is a special nursery in a hospital where sick newborns get medical care.^[7]

The most common problems premature babies experience include:

Breathing problems: Premature babies may have trouble breathing because their lungs are not fully developed. They may develop respiratory distress syndrome, a condition where the air sacs in the lungs cannot stay open due to lack of a substance called surfactant.^[5] Some babies need help breathing through a tube connected to a breathing machine called a ventilator.^[8]

Temperature control: Preemies don’t have enough body fat to hold their body temperature, so they get cold easily in normal room temperatures. This is why they are placed in an incubator (a small bed enclosed by clear plastic) or under a radiant warmer (an electrically warmed bed open to the air) to keep them warm.^[10]

Feeding difficulties: Most premature babies cannot feed directly from the breast or bottle at first because they are too immature to coordinate sucking, swallowing and breathing. They are fed slowly through a tube that goes through the nose or mouth into the stomach.^[10]

Heart problems: A common heart condition called patent ductus arteriosus (PDA) causes blood to flow away from the lungs. Premature babies may also have blood pressure that is too low or too high.^[17]

Brain complications: These include bleeding in the brain, trouble breathing, and difficulty with sucking and swallowing.^[5]

Digestive problems: Premature babies can get necrotizing enterocolitis (NEC), a serious intestinal problem that primarily affects preemies. They may also have problems with spitting up too much or yellow skin called jaundice.^[5]

Eye problems: A condition called retinopathy of prematurity involves bleeding and scarring in the retina, the seeing part of the eye.^[5]

Infections: Because their immune systems are still developing, preemies are more likely to get infections in their bloodstream (called sepsis) or around their brain (called meningitis).^[5]

Most complications go away after a while. However, babies who had severe complications may continue having problems with their breathing or vision. Babies born very early have a higher chance of long-term health problems such as cerebral palsy (a disorder affecting movement and muscle tone), hearing problems or learning disorders, but many preterm babies have no long-term problems.^[5]

Special care and treatment

Premature babies receive special medical care in the hospital’s neonatal intensive care unit (NICU). The NICU creates an environment that limits stress to the infant and meets basic needs of warmth, nutrition and protection to ensure proper growth and development.^[10]

The care premature babies receive includes:

Temperature support: Babies are placed in an incubator or under a radiant warmer to help keep them warm. A tiny thermometer taped to the baby’s skin senses their body temperature and regulates the heat.^[10]

Breathing support: Doctors may give medicine into the baby’s lungs to help them breathe. Some babies need oxygen given by mask or through a tube in the mouth attached to a breathing machine (ventilator).^[5]

Feeding support: Babies are fed through a tube until they can suck and swallow on their own. Some babies who cannot be fed through the stomach receive nutrition through an IV in the vein.^[5]

Treatment for jaundice: Babies with yellow skin are put under special ultraviolet lights to treat jaundice.^[5]

Monitoring: Healthcare providers watch the baby’s temperature, blood pressure, heart rate, breathing rate and oxygen levels closely.^[11]

Skin-to-skin contact: Parents are encouraged to hold their baby skin-to-skin, which is called kangaroo care. This helps babies stay calm and supports bonding.^[11]

Premature babies stay in the hospital until they can eat normally, are gaining weight, can maintain their body temperature in an open crib, and no longer need special medical support. This can take weeks or months, depending on how early they were born and whether they had health problems.^[5]

Feeding premature babies

Breast milk is the best nutrition for all babies, especially preemies. It has proteins that help fight infection.^[10] Premature babies have special nutritional needs because they grow at a faster rate than full-term babies and their digestive systems are immature.^[10]

Most premature babies cannot feed straight from the breast or bottle at first. Mothers can pump their milk and it is given to babies through a tube that goes through the nose or mouth into the stomach.^[10] If breast milk is not available, doctors may suggest giving the baby donor milk from a milk bank, which is safe. If breast feeding or pumping is not an option, the baby will get formula.^[10]

Preemies need more calories, proteins and other nutrients than full-term babies do. Extra nutrients called fortifiers may be added to pumped milk, or specially designed preterm formulas may be used to help the baby grow.^[10]

Babies are fed slowly because of their risk for necrotizing enterocolitis (NEC), a serious intestinal infection that primarily affects preemies.^[10] Some babies who are very small or sick receive all their nutrition through an IV. This is called total parenteral nutrition or TPN.^[15]

Going home and ongoing care

When a premature baby is ready to go home, parents need to learn how to care for their baby’s special needs. The baby’s basic needs are the same as those of any newborn baby, but there are some extra considerations.^[15]

Before leaving the hospital, parents should learn about any needed tests, including blood, hearing and vision tests, and schedule follow-up appointments.^[15] The baby should see a pediatrician within 2 to 4 days of discharge from the hospital.^[15]

Many former preemies continue to see specialists, including early-intervention specialists, neurologists, eye doctors and physical therapists, for several years to measure their vision, hearing, speech and motor skills.^[15]

Parents can expect their preemie to be smaller than average for up to 2 years or more. In time, most premature babies will have caught up to full-term babies.^[21] When tracking a premature baby’s development, it’s important to remember that their age should be adjusted based on the expected due date, not the actual birth date. Some people call this the “corrected age.”^[25]

Important care at home includes:

• Following the feeding schedule and not going longer than 4 hours between feedings^[21]
• Putting the baby to sleep on their back to reduce the risk of sudden infant death syndrome (SIDS)^[15]
• Protecting the baby from infections by washing hands often, limiting outings for the first several weeks, keeping the baby away from crowds and sick people, and ensuring all visitors are up-to-date with their vaccinations^[15]
• Not smoking or exposing the baby to smoke^[21]
• Giving iron, vitamins and other supplements the doctor recommends^[21]
• Making sure the baby gets immunizations against childhood diseases on the same schedule as full-term babies^[21]
• Holding the baby as much as possible^[21]

Reducing the risk of premature birth

While the exact cause of premature birth is often unknown, there are steps women can take to lower the chance of their baby being born too early.^[5]

Important prevention steps include:

• Going to all prenatal doctor visits^[5]
• Following a healthy diet and gaining appropriate weight during pregnancy^[2]
• Not drinking alcohol^[5]
• Not smoking or using tobacco^[5]
• Not using drugs^[5]
• Managing chronic health conditions like diabetes or high blood pressure with help from a healthcare provider^[2]
• Getting treatment for infections during pregnancy^[2]

If a woman goes into labor early, doctors may give her medicine to slow down labor or to help the baby’s lungs develop faster before birth.^[5] Women who have had a previous preterm birth should talk with their healthcare provider about their risk and what can be done to prevent another early delivery.