Why Do Babies Go to the NICU?

Hearing that your baby needs to spend time in the NICU can feel overwhelming and bring many questions. The NICU (Neonatal Intensive Care Unit) is designed to provide specialized medical care and support for newborns who need extra attention after birth.

Some babies stay in the NICU for only a few days, while others need a longer stay depending on their medical needs and the type of care they require. While many infants admitted for neonatal intensive care are born prematurely, full-term infants may also need NICU care. A NICU admission does not always mean a baby is seriously ill—sometimes they simply need extra monitoring, more time to grow, or special care as they adjust to life outside the womb.

No matter the reason for admission, the goal is always the same: to help your baby grow stronger and safely transition home.

Babies may be admitted to the NICU for a variety of reasons. Some newborns need extra monitoring after birth, while others need advanced medical care for health problems requiring closer observation or treatment. A NICU admission may happen because of something identified during pregnancy, challenges during birth, or health concerns that develop after delivery.

The most common reasons babies spend time in the NICU include:

• Prematurity

• Breathing problems

• Jaundice (yellowing of the skin)

• Low blood sugar

• Infections

• Birth complications

• Birth defects or congenital conditions

Pregnancy normally lasts about 40 weeks. Babies born before 37 weeks of pregnancy are considered premature or preterm. According to the March of Dimes 2025 Report Card, about 380,000 babies in the United States were born prematurely, meaning approximately one in ten were born early.

Some pregnancies have known risk factors for preterm birth, including high blood pressure during pregnancy, diabetes, certain infections, multiple gestation (twins or triplets), or a history of previous preterm birth. Pregnant women with these risk factors may receive additional monitoring from their health care providers, including a perinatologist (high-risk OB).

No. While premature birth is one of the most common reasons for NICU admission, not every premature baby needs intensive care. Whether a baby needs NICU support depends on several factors, including gestational age, birth weight, breathing, ability to maintain body temperature, feeding ability, and overall health.

Late preterm babies are born between 34 weeks and 36 weeks, 6 days of pregnancy. These babies are often healthy overall, but because they are born before the 37th week of pregnancy, they may need additional support, especially with feeding, as they continue developing outside the womb.

Some late preterm babies may spend time in the NICU or a special care nursery, while others may be able to remain with their mothers after birth depending on their individual needs and the care available at their hospital. With appropriate support, many late preterm babies continue to grow stronger and are able to discharge home with their families.

Because preemies are born before they have had time to fully develop, they may need additional support during the newborn period. Many of these challenges improve as babies continue to grow and mature, although some babies may need ongoing follow-up care after discharge.

Babies born early may need extra support with breathing because their lungs and nervous system are still developing. Some premature babies experience pauses in breathing (called apnea), while others may have immature lungs or respiratory problems such as respiratory distress syndrome (RDS) or transient tachypnea of the newborn (TTN).

Depending on your baby’s needs, the NICU team may provide support such as supplemental oxygen, a nasal cannula, CPAP, or other breathing assistance to help maintain a healthy blood oxygen level while your baby’s lungs continue to develop.

Premature babies may have difficulty regulating their body temperature because they have less body fat and immature temperature control systems. Some babies spend time in an incubator (isolette) or warmer until they are able to maintain a stable body temperature without additional support.

Some premature babies have difficulty maintaining stable blood sugar levels after birth. Treatment may include more frequent feedings, hand expression or pumping to provide additional breast milk, glucose gel, or supplementation with expressed colostrum, donor milk, or formula when needed.

Jaundice, or yellowing of the skin, is common in newborns—including full-term babies—and is usually temporary. It occurs when a baby has higher levels of bilirubin, a substance produced when red blood cells are broken down. Because premature babies’ livers are still developing, they may have a harder time processing bilirubin and are more likely to need treatment for jaundice.

If bilirubin levels become too high, babies may receive phototherapy lights to help their bodies process and eliminate extra bilirubin. The NICU team will monitor your baby’s bilirubin levels to determine whether additional treatment is needed.

Many premature babies need extra time to develop the strength and coordination needed for feeding. Some may experience feeding issues at first because they become tired easily while breastfeeding or bottle-feeding.

Some babies receive temporary nutrition through a feeding tube until they are strong enough to safely take full feedings by mouth. Breast milk, including expressed milk or donor milk when available, provides important nutrition and immune support during this time.

For mothers who plan to breastfeed, early and ongoing lactation support can help with pumping, milk supply, and reaching breastfeeding goals throughout their baby’s NICU journey.

Advances in neonatal care have made it possible for some babies born extremely early to receive life-saving advanced medical care in the NICU. Preemies born extremely early, especially those born before 28 weeks, often need more intensive monitoring and treatment because their organs, including their lungs, brain, and digestive system, are still developing.

Premature babies are sometimes grouped into categories based on birth weight:

• Low birth weight: 1,500g–2,500g (3.3 to 5.5 lbs)

• Very low birth weight: 1,000g–1,500g (2.2 to 3.3 lbs)

• Extremely low birth weight: Less than 1,000g (less than 2.2 lbs)

The earlier and smaller a baby is born, the more specialized support they may need with breathing, feeding, temperature regulation, growth, and other areas of development.

Although the NICU is often associated with premature babies, full-term newborns may also need specialized care after birth. Some babies require closer monitoring or temporary support for health concerns that develop during pregnancy, delivery, or the first days after birth.

Common reasons a full-term baby may be admitted to the NICU include breathing problems, infections, jaundice, low blood sugar, excessive weight loss, congenital conditions, heart defects, or other concerns that require additional observation or treatment.

A NICU stay does not always mean a baby is critically ill. Some full-term babies simply need extra support from the neonatal team before they are ready to transition home.

The NICU cares for newborns with a wide range of medical needs. Some babies need short-term monitoring and support, while others require advanced medical care for more complex conditions.

NICUs are classified into different levels based on the care they provide. Level II NICUs care for babies who need short-term specialized support, often including help with feeding, temperature regulation, or growth. Higher-level NICUs (Level III and IV) care for very premature babies and newborns with more complex medical needs, including breathing problems, serious infections, congenital conditions, heart defects, or conditions that require surgery or care from pediatric specialists.

Providing breast milk can offer important benefits for premature and medically fragile newborns. Babies who receive their mother's own milk (sometimes called "MOM" in the hospital) have been found to have lower risks of infections and feeding intolerance, and shorter hospital stays. Breast milk also provides nutrients and bioactive components that support healthy brain, nerve, and digestive development.

For many mothers, breastfeeding in the NICU looks different than expected. Some babies are able to begin nursing right away, while others need time to develop the strength and coordination needed to breastfeed. Pumping and providing expressed breast milk is an important way mothers can provide nutrition for their baby while they continue to grow. Lactation consultant support can help mothers establish milk supply, navigate pumping, and work toward their feeding goals.

Many NICUs encourage families to participate in their baby's care as much as possible. When medically appropriate, skin-to-skin contact (often called kangaroo care) can help regulate a baby's heart rate, breathing, temperature, and stress levels while supporting bonding and breastfeeding. Even babies receiving milk through a feeding tube can often benefit from skin-to-skin care and opportunities to practice breastfeeding as they become stronger.

Your healthcare team—including nurses, neonatologists, respiratory therapists, lactation consultants, and other specialists—works together to provide care, monitor your baby’s progress, support feeding and growth, and help your family prepare for a safe transition home.

Every baby’s journey is unique. The length of a NICU stay depends on many factors, including a baby’s gestational age, medical needs, feeding ability, breathing, and overall progress.

For premature babies, those born earlier in pregnancy often need a longer stay because they need more time to grow and develop before going home. Many preemies are discharged around their original due date, although some may be ready sooner while others may need additional time and support.

The average hospital stay for a NICU baby varies widely. Some need special care for only a few days, while others may require weeks or months of advanced medical care. Your baby’s healthcare team will monitor your baby’s progress and help determine when your baby is ready to transition home safely.

While seeing your baby in the NICU can be emotional, remember that the NICU was designed to provide the extra time, monitoring, and treatment they need to grow stronger. Many babies who spend time in the NICU go on to continue growing, developing, and thriving at home.

Leaving the NICU is an exciting milestone, but it can also bring a mix of emotions as families transition from a highly supported hospital environment to caring for their baby at home. Before discharge, families receive education from their healthcare providers about feeding, medications, follow-up appointments, safe sleep, and signs to watch for at home.

The goal is to help families feel confident caring for their baby and understand how to continue meeting their baby’s needs after leaving the hospital.

Babies discharged from the NICU typically have follow-up appointments with their pediatrician within a few days of going home. Many preemies also receive ongoing monitoring through follow-up clinics to track growth, development, and their overall progress. Some may benefit from additional support from specialists such as physical, occupational, or speech therapists.

Ways to keep your baby healthy after discharge include keeping up with recommended vaccinations, avoiding exposure to tobacco smoke, being mindful of illness exposure (especially during respiratory illness season), and continuing to provide breast milk whenever possible. Even small amounts of breast milk can provide valuable nutrition and immune support for your baby.

A NICU stay may not have been part of the birth experience you imagined, but it does not define your baby’s future. You are an important part of your baby’s care team, and your healthcare providers and lactation consultants are there to guide you throughout this journey.

Whether you are preparing for a possible NICU stay or currently providing milk for your baby in the NICU, resources are available. Aeroflow Breastpumps offers a NICU Feeding Prep & Support Class to help families understand what to expect, learn strategies for providing breast milk, and prepare for common feeding challenges.

Our lactation consultants can also provide ongoing support with pumping, milk supply, and feeding goals throughout your journey. From your first pumping session to transitioning home, you do not have to navigate your NICU experience alone.