Reasons Your Baby Might Need Admitted to the NICU

Most people associate the NICU (neonatal intensive care unit) as a place where premature newborn babies go after birth. Although the majority of newborns admitted to NICUs are premature babies (“preemies”), interestingly enough, if you walk around any NICU you will see plenty of babies who are full-term, and even some who arrived a week or two after their due date! On average, 360,000 newborns in the U.S. need neonatal intensive care after birth each year. Some only need to stay in the NICU for a few days, while others may be admitted for several months based on baby needs.  Level 2 NICUs provide health care for preemies who are about 32 weeks’ gestation or older and do not need a lot of breathing support, Level 3 NICUs can care for all sizes and ages of preemies, and Level 4 NICUS provide care for all preemies, including the smallest and most sick, as well as critically ill full-term newborns who need surgery, have birth defects, and other medical conditions requiring a care team of neonatologists and multiple pediatric subspecialty teams. 

Pregnancy lasts for 40 weeks. Babies born before 37 weeks’ gestation, more than 3 weeks before their due date, are premature. Per the March of Dimes 2002 Report Card, 10.5% of newborns in the U.S. born in 2022 were premature which means that 30,000 preemies are born every month. 

Risk factors for having a preemie include high blood pressure during pregnancy, diabetes, certain infections, multiple gestation (twins or triplets), and having a history of giving birth prematurely in the past.  Pregnant women who experience any of these risk factors for preterm delivery should be followed closely by a perinatologist (“high risk OB”) during pregnancy.

The largest group of premature infants are considered to be “late preterm,” meaning they are born between 34-36 weeks’ gestation. For the most part, newborns who are born at less than 35 weeks will be automatically admitted to a NICU after birth. Some late preemies who are between 35-36 weeks are stable enough to be able to stay in the newborn nursery and may not need NICU care. 

The smallest newborns that survive and can be admitted to NICUs are those born at 22 weeks’ gestation (18 weeks before they are due to be born). Preemies, born between 22-34 weeks are divided into three main categories based on birth weight (BW):

Low birth weight: BW between 1500g-2500g (3.3 to 5.5 lbs)

Very low birth weight: BW between 1000g-1500g (2.2 to 3.3 lbs)

Extremely low birth weight: BW less than 1000g (less than 2.2 lbs)

The smallest preemies who can survive nowadays are around 400g at birth (0.88 lbs)

The earlier that a preemie is born, the longer their expected NICU stay for special care. As a rule of thumb, we estimate that a baby who is admitted to the NICU will be discharged home around their due date. So if a baby is born 12 weeks prematurely (at 28 weeks’ gestation), we’d expect them to spend about 3 months in the NICU. The smallest preemies, born between 22-23 weeks, may need to be hospitalized for more than 6 months (and in the minority of cases for more than one year depending on baby’s condition!) Likewise, the survival of premature newborns is directly correlated with their gestational age at birth. For example, 60-70% of babies born at 24 weeks survive, over 90% of babies born at 27 weeks survive, and over 95% of babies born at 30 weeks survive. The smallest preemies who survive in the NICU and are discharged home have the highest risk of handicaps and long-term medical problems.

The earlier that a preemie is born, the longer their expected NICU stay for special care. As a rule of thumb, we estimate that a baby who is admitted to the NICU will be discharged home around their due date. So if a baby is born 12 weeks prematurely (at 28 weeks’ gestation), we’d expect them to spend about 3 months in the NICU. The smallest preemies, born between 22-23 weeks, may need to be hospitalized for more than 6 months (and in the minority of cases for more than one year depending on baby’s condition!) Likewise, the survival of premature newborns is directly correlated with their gestational age at birth. For example, 60-70% of babies born at 24 weeks survive, over 90% of babies born at 27 weeks survive, and over 95% of babies born at 30 weeks survive. The smallest preemies who survive in the NICU and are discharged home have the highest risk of handicaps and long-term medical problems.

1. Respiratory distress syndrome (RDS). This is the medical term for having immature lungs. Newborns with RDS require help and assistance with breathing so that their bodies can get enough oxygen and get rid of carbon dioxide. Treatments for RDS include getting extra oxygen through a nasal cannula, continuous positive airway pressure (CPAP), and mechanical ventilation (getting help with breathing through a special machine). Although the lungs of most babies with RDS grow and heal, they sometimes develop a chronic condition called bronchopulmonary dysplasia (BPD) and need to be discharged home on oxygen.
2. Infections. Preemies are at a much higher risk of infections, including bacterial sepsis, due to having immature immune systems. Anytime there is a concern for an infection in a NICU patient, a blood culture will be drawn and IV antibiotics will be started as a precaution.
3. Intraventricular hemorrhage (IVH). This is bleeding in the fluid filled spaces of the brain due to immature blood vessels. Most cases of IVH are mild and resolve with no long-term consequences. Preemies with more severe cases of IVH need to be followed closely due to a risk of hydrocephalus and long-term problems with development.
4. Anemia. This occurs when there are not enough red blood cells, the part of the blood that carries oxygen from the lungs to the body. In most cases anemia in preemies is as a result of having immature bone marrow. If anemia is severe enough a blood transfusion may need to be given while in the NICU.
5. Patent ductus arteriosus (PDA). A PDA is when a blood vessel that connects the circulation of the lungs and the heart (ductus arteriosus) stays open. This can lead to problems if too much blood flows into the lungs. PDAs can be treated with medications or surgery, if necessary.
6. Feeding intolerance. The digestive system is one of the last parts of the body to develop, so many preemies in the NICU have slow digestion. As a result of this they may develop symptoms of feeding intolerance which include belly distension, constipation, and/or lots of spitting up or vomiting. The best way to prevent feeding intolerance is to make sure that your preemie gets only breastmilk and not infant formula. If a mother is unable to pump milk to feed her baby, donor breast milk can be given as an alternative or supplement to mothers’ milk. 

NICU patients who receive their mothers’ breast milk have been found to have lower risks of infections, less feeding intolerance, shorter NICU hospital stays, and a lower risk of BPD. Breastfeeding also promotes healthy brain and nerve growth. Initiating breastfeeding in the NICU requires dedication and patience, along with having the proper equipment, skills, and lactation consultant support. For tips on pumping in the NICU please see our previous blog post about initiating breastfeeding in the NICU. 

The most common medical conditions that lead full-term newborns to require neonatal intensive medical care include birth defects, heart problems, infections, hypoglycemia, medication withdrawal, jaundice, dehydration, problems with metabolism, and neurological problems such as seizures or strokes. 

Babies who are discharged home from the NICU usually see their pediatricians for follow-up within a few days of going home. Many preemies will also have outpatient follow-up with healthcare providers within a few months in a NICU follow-up clinic to have their growth and development monitored. Most preemies with delayed developmental milestones during the first 2 years of life will eventually catch up with their peers. All preemies should be assessed to see if they’d benefit from working with physical, occupational, and/or speech therapists as an outpatient after going home.

The best ways to keep your preemie healthy after NICU discharge include avoiding any exposure to tobacco smoke, making sure they stay up to date on their vaccines, being cautious with having visitors in the home and exposing them to crowds (especially during the winter months), and continuing to feed them breastmilk as long as possible, even if it’s just small amounts at a time. 

References

• March of Dimes Report Card 2022. Accessed online 9/17/2023.  
• Pineda, R., Kati Knudsen, Breault, C.C. et al. NICUs in the US: levels of acuity, number of beds, and relationships to population factors. J Perinatol 43, 796–805 (2023).