Childbirth is a complex process. There are numerous physical changes that occur in babies as they adjust to life outside of the womb. Leaving the womb means they can no longer depend on the mother’s placenta for critical body functions, such as breathing, eating, and eliminating waste. As soon as babies enter the world, their body systems must change dramatically and work together in a new way. Some of the major changes that need to take place include the following:

  • The lungs must fill with air and provide the cells with oxygen.
  • The circulatory system must change so blood and nutrients can be distributed.
  • The digestive system must begin processing food and excreting waste.
  • The liver and immune system must start working independently.

Some babies have difficulty making these adjustments. This is more likely to happen if they’re born prematurely, which means before 37 weeks, they have a low birth weight, or they have a condition that requires immediate medical attention. When babies need special care after delivery, they’re often admitted to an area of the hospital known as the neonatal intensive care unit (NICU). The NICU has advanced technology and has teams of different healthcare professionals to provide specialized care for struggling newborns. Not all hospitals have a NICU and babies who need intensive care may need to be transferred to another hospital.

Giving birth to a premature or sick infant can be unexpected for any parent. The unfamiliar sounds, sights, and equipment in the NICU can also contribute to feelings of anxiety. Knowing the types of procedures that are done in the NICU may provide you with some peace of mind as your little one receives care for their specific needs.

Nutritional support is needed when a baby has difficulty swallowing or has a condition that interferes with eating. To ensure the baby still receives vital nutrients, the NICU staff will feed them through an intravenous line, which is called an IV, or a feeding tube.

Feeding Through an Intravenous Line (IV)

Not many premature or low birth weight babies can be fed during the first few hours in the NICU, and many sick babies are unable to take anything by mouth for several days. To make sure your baby is getting adequate nutrition, the NICU staff starts an IV to administer fluids containing:

  • water
  • glucose
  • sodium
  • potassium
  • chloride
  • calcium
  • magnesium
  • phosphorus

This type of nutrition support is called total parenteral nutrition (TPN). A healthcare provider will place an IV in a vein located in your baby’s head, hand, or lower leg. A single IV typically lasts for less than one day, so the staff may place several IVs during the first few days. However, most babies eventually need more nutrition than these small IV lines can supply. After several days, the staff inserts a catheter, which is a long IV line, into a larger vein so your baby can get higher amounts of nutrients.

Catheters may also be placed in both the umbilical artery and vein if your baby is very small or sick. Fluids and medications can be given through the catheters and blood can be drawn for laboratory tests. More concentrated IV fluids can also be given through these umbilical lines, allowing the baby to obtain better nutrition. Additionally, umbilical lines last at least one week longer that smaller IVs. Umbilical arterial lines can also be connected to a machine that continuously measures the baby’s blood pressure.

If your baby needs TPN for longer than one week, doctors often insert another type of line, called a central line. A central line can remain in place for several weeks until your baby no longer needs TPN.

Feeding by Mouth

Feeding by mouth, also known as enteral nutrition, should be started as soon as possible. This type of nutritional support encourages your baby’s gastrointestinal (GI) tract to grow and begin functioning. A very small baby may first need to be fed through a small plastic tube that goes through the mouth or nose and into the stomach. A small amount of breast milk or formula is given through this tube. In most cases, the baby is given a combination of TPN and enteral nutrition at first, as it can take awhile for the GI tract to become accustomed to enteral feedings.

A baby needs approximately 120 calories per day for every 2.2 pounds, or 1 kilogram, of weight. Regular formula and breast milk contain 20 calories per ounce. A baby of extremely low birth weight should receive special formula or fortified breast milk containing at least 24 calories per ounce to ensure adequate growth. The fortified breast milk and formula contain more nutrients that can be digested easily by a low birth weight baby.

It can take some time before all of a baby’s nutritional needs can be met through enteral nutrition. The intestines of a small baby usually aren’t able to tolerate rapid increases in the amount of milk or formula, so increases in feedings must be done cautiously and gradually.

The NICU staff may also perform various other procedures and tests to ensure the baby’s care stays on track.


X-rays are one of the most commonly performed imaging tests in the NICU. They allow doctors to see the inside of the body without having to make an incision. In the NICU, X-rays are most often done to examine the baby’s chest and evaluate lung function. An X-ray of the abdomen may also be performed if the baby is having difficulty with enteral feedings.


Ultrasound is another type of imaging test that may be performed by the NICU staff. It uses high-frequency sound waves to produce detailed images of various body structures, such as organs, blood vessels, and tissues. The test is harmless and doesn’t cause any pain. All premature and low birth weight babies are routinely evaluated using an ultrasound test. It’s often used to check for brain damage or bleeding in the skull.

Blood and Urine Tests

The NICU staff may order blood and urine tests to evaluate:

Blood Gases

Gases in the blood include oxygen, carbon dioxide, and acid. Blood gas levels can help the staff assess how well the lungs are functioning and how much breathing assistance may be needed. A blood gas test usually involves taking blood from the arterial catheter. If the baby doesn’t have an arterial catheter in place, a blood sample can be obtained by pricking the baby’s heel.

Hematocrit and Hemoglobin

These blood tests can provide information on how well oxygen and nutrients are being distributed throughout the body. Hematocrit and hemoglobin tests require a small sample of blood. This sample may be obtained by pricking the baby’s heel or by removing blood from the arterial catheter.

Blood Urea Nitrogen (BUN) and Creatinine

Blood urea nitrogen and creatinine levels indicate how well the kidneys are functioning. BUN and creatinine measurements can be obtained through either a blood test or urine test.

Chemical Salts

These salts include sodium, glucose, and potassium, among others. Measuring the levels of chemical salts can provide comprehensive information about a baby’s overall health.

Blood and Urine Tests

These blood and urine tests may be performed every few hours to ensure the baby’s body systems and functions are steadily improving.

Procedures to Measure Fluids

The NICU staff measures all the fluids a baby takes in and all the fluids a baby excretes. This helps them determine whether fluid levels are in balance. They also weigh the baby frequently to assess how much fluid the baby needs. Weighing the baby daily also allows the staff to evaluate how well the baby is doing.

Blood Transfusions

Babies in the NICU often require blood transfusions either because their blood-forming organs are immature and aren’t producing enough red blood cells or because they may be losing a lot of blood due to the number of blood tests that need to be performed

Blood transfusions replenish the blood and help ensure the baby stays healthy. The blood is given to the baby through an IV line.

It’s normal to feel concerned about your baby while they’re in the NICU. Know that they’re in safe hands and that the staff is doing all they can to improve your child’s outlook. Don’t be afraid to voice your concerns or to ask questions about the procedures being performed. Becoming involved in your baby’s care can help ease any anxiety you may be feeling. It may also help to have friends and loved ones with you while your baby is in the NICU. They can provide support and guidance when you need it.