A premature birth means a baby is born too early. The birth takes place before the 37th week of pregnancy. A typical pregnancy lasts about 40 weeks.

Premature babies often have serious health problems, especially when they’re born very early. These problems often vary. But the earlier a baby is born, the higher the risk of health challenges.

A newborn can be:

Most premature births happen in the late preterm stage.

Your baby may have very mild symptoms of premature birth or more-serious health problems.

Some signs of being born too early include:

The following tables show the median birth weight, length and head circumference of premature babies at different gestational ages for each sex.

Weight, length and head circumference by gestational age for boys
Gestational age Weight Length Head circumference
40 weeks 7 lbs., 15 oz.
(3.6 kg)
20 in. (51 cm) 13.8 in. (35 cm)
35 weeks 5 lbs., 8 oz.
(2.5 kg)
18.1 in. (46 cm) 12.6 in. (32 cm)
32 weeks 3 lbs., 15.5 oz.
(1.8 kg)
16.5 in. (42 cm) 11.6 in. (29.5 cm)
28 weeks 2 lbs., 6.8 oz.
(1.1 kg)
14.4 in. (36.5 cm) 10.2 in. (26 cm)
24 weeks 1 lb., 6.9 oz.
(0.65 kg)
12.2 in. (31 cm) 8.7 in. (22 cm)
Weight, length and head circumference by gestational age for girls
Gestational age Weight Length Head circumference
40 weeks 7 lbs., 7.9 oz.
(3.4 kg)
20 in. (51 cm) 13.8 in. (35 cm)
35 weeks 5 lbs., 4.7 oz.
(2.4 kg)
17.7 in. (45 cm) 12.4 in. (31.5 cm)
32 weeks 3 lbs., 12 oz.
(1.7 kg)
16.5 in. (42 cm) 11.4 in. (29 cm)
28 weeks 2 lbs., 3.3 oz.
(1.0 kg)
14.1 in. (36 cm) 9.8 in. (25 cm)
24 weeks 1 lb., 5.2 oz.
(0.60 kg)
12.6 in. (32 cm) 8.3 in. (21 cm)

Special care

If you give birth to a preterm baby, your baby will likely need to stay in a special nursery unit at the hospital. Some infants need to spend time in a unit that cares for them and closely tracks their health day and night. This is called a neonatal intensive care unit (NICU).

A step down from the NICU is an intermediate care nursery, which provides less intensive care. Special nursery units are staffed with health care providers and a team that’s trained to help preterm babies.

Your baby may need extra help feeding and adapting right after delivery. Your health care team can help you understand what’s needed and what your baby’s care plan will be. Feel free to ask them questions.

Often, the exact cause of premature birth isn’t clear. But certain things can raise the risk.

Some risk factors linked to past and present pregnancies include:

Some health problems can raise the risk of premature birth, such as:

Lifestyle choices also can raise the risk of a preterm pregnancy, such as:

For unknown reasons, Black and Native people in the United States are more likely to have premature births than are women of other races. But premature birth can happen to anyone. In fact, many preterm births have no known risk factors.

Not all premature babies have health complications. But being born too early can cause short-term and long-term medical problems. In general, the earlier a baby is born, the higher the risk of complications. Birth weight plays a key role too.

Some problems may be clear at birth. Others may not show up until later.

Short-term complications

In the first weeks, the complications of premature birth may include:

Long-term complications

Over the long term, premature birth may lead to health problems such as:

The exact cause of preterm birth is often unknown. But some things can be done to help lower the risk of preterm birth, including:

One thing that doesn’t help prevent preterm birth is staying in bed. Bed rest can raise the risk of blood clots, weaker bones and less muscle strength. It might even make preterm birth more likely.

A premature baby in the NICU may need to have many tests. Some tests are ongoing. Other exams may be done only if the NICU staff thinks the baby might have a certain health problem.

Tests your premature baby may need include:

More tests may be needed if your baby has other health problems.

The neonatal intensive care unit (NICU) or special care nursery closely tracks your premature baby’s health.

Supportive care

This type of care for your baby may include:

Medications

Medicines may be given to your baby for different reasons. For instance, some medicines help the lungs and heart work better. Depending on your baby’s health, the medicines they receive may include:

Surgery

Sometimes surgery is needed to treat a premature baby’s health problems. Talk with your baby’s health care team to understand which complications may lead to surgery. Learn about the types of surgery that might be needed to treat these problems too.

Taking your baby home

The following signs mean your baby is ready to go home:

The hospital may let a baby go home before meeting one of these requirements. But the baby’s medical team and family first need to set up and agree on a plan for home care and follow-up health care.

Your baby’s health care team will help you learn how to care for your baby at home. Before your baby can leave the hospital, your baby’s nurse or a hospital discharge planner may ask you questions about:

The thought of bringing your baby home from the hospital might make you feel relieved, excited and nervous. You can do some things ahead of time to prepare for life at home:

Caring for a premature baby can be very tiring. You may be anxious about your baby’s health. You also might feel angry, guilty or overwhelmed.

Some of these tips may help during this hard time:

Caring for a premature baby is a great challenge. Take it one day at a time. Despite the worries and setbacks, celebrate your preemie’s strength and ability to adapt. Cherish the time you can spend getting to know your child.

As the parent of a premature baby in the neonatal intensive care unit (NICU), you’ll talk with many care providers for your baby. Members of the NICU team caring for your infant may include:

You also might meet with a pediatric social worker. This professional can help you find services that might be useful during and after your baby’s hospital stay.

Ideally, you’ll work together with your baby’s care providers. Over time, they can show you how to hold, feed and care for your baby.

What you can do

It’s OK to ask the NICU care team any questions you have about your baby’s condition. Or you can write down your questions and get answers when you’re ready.

For instance, you could ask:

You also can ask how to help care for your baby:

You may have questions about taking your baby home too:

During your baby’s time in the NICU, feel free to ask the staff how you can become more involved in your baby’s care. It can give you confidence as a new parent. It also can make life easier once you bring your child home.

© 1998-2024 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.

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