Understanding Premature Infant Development

The birth of a baby can be a joyful time for families. It can also be a time of questions and concerns. When babies are born too soon (premature), parents may worry about how their infant will grow and develop.

Premature (“preemie”) babies may differ in their growth and development compared to full-term babies. But every baby, whether premature or full-term, follows their own developmental timeline, says Liz Smith, APRN-NP, neonatal nurse practitioner at Lurie Children’s.

Here, Smith explains what parents and caregivers need to know about how premature babies grow and develop.

What is a premature baby?

A premature, or preterm, baby is an infant born before 37 full weeks of pregnancy. A typical pregnancy progresses to about 40 weeks. 

Are there different types of prematurity?

Healthcare providers classify prematurity by how early an infant arrives. Preterm babies may be:

• Late premature babies: born between 34 and 36 to 37 weeks
• Moderately premature: born between 32 and 34 weeks
• Very premature: born between 28 and 32 weeks
• Extremely premature: born at 28 weeks of pregnancy or earlier

Babies born very early have the highest risk of experiencing complications. Babies who stay in the uterus (in utero) longer have more time to grow and develop.

Do premature infants have health problems? 

Your baby continues to grow and develop as pregnancy progresses. Their heart and blood vessels are usually fully developed between 35 and 37 weeks of pregnancy. Their lungs continue to mature, and bones and muscles develop during the final weeks in utero. 

Babies born prematurely don’t have the time they need in the uterus to develop fully. They may experience physical and developmental differences that can cause complications. But it’s important to note that not all premature babies experience health issues. 

Physical Differences

Many premature infants have organs that haven’t fully developed. This is especially true if a baby is extremely premature or very premature. These newborns may have underdeveloped:

• Brain
• Eyes
• Heart
• Kidneys
• Liver
• Lungs
• Skin

Babies born prematurely are at higher risk for certain complications, including:

• Difficulty breathing (respiratory distress syndrome)
• Feeding problems 
• Trouble maintaining healthy body temperature (98.6 F)
• Vision and hearing problems

Developmental Differences

While many preterm babies catch up to their peers developmentally, some infants may develop health conditions as they get older. Preterm babies can be at higher risk for developmental differences. These can include:

• Cerebral palsy, a brain condition that affects balance and movement
• Developmental delays, such as trouble with language or movement
• Learning disorders, such as difficulty with reading, math or writing

Tests Premature Babies May Have

Healthcare providers may diagnose some health conditions right away. “A specialized provider team examines preterm infants after birth to assess for health conditions related to prematurity,” Smith says. “We assess how all of their systems are responding to their new environment.”  

Healthcare providers may want to do certain tests to learn more about your baby’s health. Your baby may have:

• Blood tests: Your baby’s care team takes a small sample of their blood to make sure their organs are functioning as they should. 
• X-rays: Providers use X-rays to assess the anatomy of your baby’s bones and organs. These images can help identify problems with these organs.
• Ultrasound: Specialists use a machine that uses sound waves to create images of your baby’s organs (ultrasound). They do this to identify potential problems with the organs. 

What is the NICU?

The neonatal intensive care unit (NICU) is a special area in the hospital. Healthcare providers who are experts in caring for very small or sick babies work in the NICU. These specialists care for your baby around the clock. They monitor your baby’s:

• Breathing
• Feeding
• Temperature
• Heart rate

What does it mean if my baby must go to the NICU?

All babies born before 35 weeks and who weigh less than 2,000 grams (about 4.5 pounds) go to the NICU. They get specialized infant care even if they appear well during an exam, Smith says. This care helps make sure your baby is safe while they continue to mature. 

Smith says parents are encouraged to hold their baby in the NICU. “We try to promote infant holding as early and often as the baby’s condition allows,” she says.

You may wonder how long your baby will stay in the NICU. Depending on their health needs, they may stay in the NICU for a few days, weeks or months. “Some babies have no complications at all and go home as soon as a week after birth, and some take a little longer,” Smith says. 

When your baby meets certain goals related to maintaining adequate nutrition, body temperature, and breathing, they can go home. “We make sure your baby meets all care goals, so you don’t have to worry when you take them home.”

As Your Premature Baby Grows

Your baby may have a team of healthcare providers who work together to keep them as healthy as possible as they grow. Depending on their needs, some children may receive care from a:

• Dietitian
• Respiratory therapist
• Occupational therapist (helps kids achieve developmental milestones)
• Neonatologist and neonatal nurse practitioner
• Pharmacist
• Physical therapist
• Speech therapist

“We work together to advance your baby’s growth and development and monitor their progress,” Smith says. “Rapid growth happens over the first months to years of life. Early intervention and monitoring is key to successful progress.”

Will my premature baby catch up in development and growth?

Early intervention and therapy play an important role in how a premature baby grows and develops. Premature babies may experience behavior differences and language and learning delays as they grow into childhood.

“If preterm care is needed, a dedicated team of specialists is committed to the overall health and development of your baby. The majority of preterm babies catch up with growth and development, especially with early intervention,” Smith says.

Learn more about the NICU-Cardiac Neurodevelopmental Program’s Early Childhood Clinic at Lurie Children’s.

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