Nutrition and Fluids

March 21, 2017

Nutrition and Fluids

Nutrition for babies in the NICU

Feeding babies in the NICU is quite different from feeding healthy babies. When babies are sick or premature, they are often not well enough to breastfeed or take a bottle. Premature babies may not be able to suck effectively, or their GI (gastrointestinal) tracts may not be mature enough to digest feedings. Babies who are medically unstable are often unable to take regular feedings. Babies with umbilical catheters and those who need help breathing, such as with a mechanical ventilator, may not be able to be fed because of the risk of problems such as aspiration (breathing food into the lungs).

IV fluids and parenteral nutrition

Many babies in the NICU receive essential fluids and electrolytes through an IV (intravenous) tube in a vein. Some babies may need a special preparation called parenteral nutrition (PN) or hyperalimentation, which has nutrients they need until they are able to take milk feedings.

The contents of IV fluids and PN are carefully calculated for each baby. Calories, protein, fats, and electrolytes including sodium, potassium, chloride, magnesium, and calcium are all important components. Babies need calories, protein, and fats for adequate growth and development. Fluids, electrolytes, and vitamins are needed for proper functioning of the body's systems.

Blood tests help determine how much of each component a baby needs and the amount of each nutrient can be increased or decreased accordingly. Daily weights and keeping track of a baby's urine output also help monitor fluid needs.

Monitoring your baby's electrolyte and blood levels

Some babies have too much or too little of certain electrolytes or other components in the blood. As a result, some common problems include the following:

  • Hypernatremia. High amounts of sodium (salt) in the blood.

  • Hyperkalemia. High amounts of potassium in the blood; can be diagnosed by blood test, or by changes in the baby's heart rate pattern.

  • Hyperglycemia. High amounts of glucose (sugar) in the blood; diagnosed by blood tests, often done by heel stick; some babies may need insulin to control high glucose levels.

  • Hypoglycemia. Low blood sugar; usually treated with IV fluids containing dextrose (another form of sugar).

  • Hypocalcemia. Low calcium levels in the blood; usually treated with calcium in IV fluids.

Is your baby ready for milk feedings?

Even babies younger than 28 weeks gestation can benefit from milk feedings. Very early preterm infants are given trophic feedings in very small amounts by tube feeding. Trophic means that these feedings help the digestive tract mature and grow. The amount of milk is very slowly increased over days to weeks. Once your baby is able to handle large enough amounts of milk feedings, IV fluids and PN can be slowly decreased.

Sick babies may not be strong enough to suck effectively. Premature babies may not be physically mature enough to coordinate sucking, swallowing, and breathing. Or they may be too weak to suck for long periods of time. Sucking is the earliest sign that a baby is getting ready to practice feeding by mouth. It also has a calming effect. The best place for the baby to practice sucking and learn to feed is at the mother’s breast. However small pacifiers designed for premature babies may be used for comfort and practice when mothers aren't available. It also seems to be helpful for premature babies to have drops of their mother's colostrum by mouth even if they aren't mature enough to feed by mouth.

Feeding your baby in the NICU

The following are some ways babies may be fed in the NICU:

  • Gavage or tube feedings. Premature babies, especially those younger than 32 to 36 weeks gestation, often can’t be fed from the breast or bottle. Gavage or tube feedings may be needed until the baby learns to suck well. For gavage feedings, a small flexible tube is placed into a baby's nostril or mouth and passed down into the stomach. The tube is usually left in place until the baby is consistently able to feed by mouth. At first, tiny amounts of breastmilk or formula are given through the feeding tube. Because of their small stomach size, very tiny babies may be fed using a pump that slowly delivers the milk in small amounts. As the babies grow, they are able to slowly take larger amounts at each feeding. Before each tube feeding, a baby may be checked for residual. This is the amount of milk in the stomach left over from the last feeding. If the amount of residual is higher than expected, it may mean the baby is not digesting food well.

  • Cup or spoon feedings. Some NICUs use soft flexible feeding cups or shallow feeding spoons instead of bottles for babies who are learning to breastfeed.

  • Nipple feedings. Feeding practice from breast or bottle can begin as soon as babies are stable and are able to suck well. Your baby will probably begin to practice feeding by mouth while still being tube fed. Even if a baby shows interest and participates in a feeding, it can be tiring. It is always important to pay attention to behavioral cues that show tiredness. If you are using a bottle, it’s important to help your baby pace the feeding. Learning to feed by mouth is a gradual developmental process that can take several weeks for premature babies. So it’s normal to take only occasional small amounts by bottle or at the breast. To find out how much milk a baby is transferring at the breast, he or she can be weighed before and after the feed using a special scale. As your baby increases the amount he or she can safely and comfortably take by nipple, the amount in the tube feedings can be decreased. 

Why breastmilk is important and how lactation consultants can help

A mother's milk is the preferred milk for all babies, especially the most premature babies. Breastmilk contains all the nutrients needed for growth and development. Although commercial formulas are designed to be close to human milk, most are based on cow's milk protein. This is different from human protein. The proteins and fats in breastmilk are more easily digested. Because of these differences in digestion, formula may not be as well tolerated. In addition, breastmilk contains antibodies and other immune factors from the mother to help protect babies from infection. This is something that commercial formulas don’t have. This protection is especially important when babies are sick or premature and have higher chances of developing an infection. Necrotizing enterocolitis, an especially dangerous condition in very premature infants, is more common in babies who don't receive breastmilk. In the longer term, more breastmilk feedings seem to lead to more brain growth for premature babies.

Very premature babies may need supplements added to breastmilk to meet their increased needs for protein, calcium, and phosphorus. Even if your baby can’t breastfeed, you can pump your breastmilk and it can be stored for gavage or nipple feedings. Depending on the amount of milk needed for feedings, donor milk or formula may need to be given temporarily in addition to a baby's own mother's milk. Donor milk is pasteurized before it is given and may lose some nutritional value. But it is more beneficial for premature infants than formula. It is an important option when the mother's breastmilk is not available.

Certified lactation consultants (IBCLC) are nurses or other healthcare providers who are specially trained and certified to help women with breastfeeding. In the NICU, these professionals can help you and your baby become comfortable nursing. They can also teach you about pumping and storing your breastmilk for your baby. Because learning to feed by mouth is a process that can take babies several weeks, you will likely need to keep expressing milk even after leaving the NICU.


March 21, 2017


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Reviewed By:  

Freeborn, Donna, PhD, CNM, FNP,Lee, Kimberly G., MD, MSc, IBCLC