Your Preemie's Development: Birth to Age 2

Reviewed by Renee A. Alli, MD on June 16, 2021
photo of premature baby

If you're the new parent of a preemie -- a baby born earlier than 37 weeks -- you may have spent the last few days, weeks, or even months living minute-to-minute, focused on weights, measurements, and tests.

But as things settle down, you may start thinking more about what you and your child can expect in the next couple of years.

Most preemies grow up to be healthy kids. They tend to be on track with full-term babies in their growth and development by age 3 or so.

Your baby's early years, though, may be more complicated than a full-term baby's. Because they're born before they're ready, almost all preemies need extra care. They're more likely to have health issues and delays in development during their early years, and sometimes beyond.

What Affects Growth and Development?

How early they were born. In general, the earlier your baby was born, the more likely they are to have lasting problems that affect their growth and development.

Doctors divide preemies into groups depending on how old they are at birth:

  • Late preterm: Between 34 weeks and less than 37 weeks
  • Moderately preterm: Between 32 and 34 weeks
  • Very preterm: Less than 32 weeks
  • Extremely preterm: 25 weeks or less

Late preterm babies tend to catch up to full-term babies quickly. Babies who were born earlier than that may develop more slowly and have setbacks. Extremely preterm babies are more likely to have serious, lasting disabilities.

Birth weight. The less your baby weighed when they were born, the more likely they are to have health problems that could affect how they grow.

Whether they have other health conditions. Preemies are more likely to have medical issues like infections or heart, lung, or intestinal conditions. Doctors can treat these problems, and some go away as your baby gets older. They may still slow down your child's growth and development. Your baby may need extra time to build up their strength.

How complicated treatment was in the hospital. If your baby spent a long time in the neonatal intensive care unit (NICU) and needed a lot of special care, they are likely to need extra time to develop.

Developmental Milestones

Doctors and parents track development by noting when babies learn key skills, like smiling, rolling over, or crawling. You and your doctor can compare this with the average age that babies reach these milestones.

Keep in mind that the ages that babies are supposed to meet milestones are always rough estimates, even for full-term babies. And when you're looking at a chart of developmental milestones, you need to use your baby's "corrected age"-- also called adjusted age -- instead of their actual age. Your baby's corrected age is based on your due date -- the age your baby would be if they had been born full-term.

If you want to do the math yourself, subtract the number of weeks they were born early from their current age. For example, if your baby is 18 weeks old but was born 8 weeks early, their corrected age would be 10 weeks.

If you want to keep tabs on your preemie's development, always use your baby's corrected age for milestones at least until age 2 or so. Around then, most preemies have caught up, so it's usually OK to use their real age instead.

As Your Baby Grows: Tips for Parents

Watching your baby develop and grow over the next 2 years is going to be exciting -- and maybe a bit stressful too. Follow some simple tips that can keep you from getting overanxious.

Remember that preemies are different from full-term babies. Your baby may be fussier and not respond to you in the same way as a full-term baby. They may have more trouble sleeping through the night. Most preemies grow out of these problems during their first year.

Don't worry too much about milestones. No baby -- whether they're full-term or premature -- develops on an exact schedule. If your child doesn't meet a milestone right on time, it's not usually something to worry about. If you have concerns, discuss with your pediatrician. They can validate your concerns and discuss strategies to promote your baby's development.

Focus more on progress than specific targets. Don't get hung up on the exact age your baby reaches this or that milestone. Look at the advances they make instead. All babies babble before they say their first word. They'll stand before they can walk. For the first 6 months, they gain about 1 pound per month. As long as your baby is moving forward in their development, that's what's important.

Keep your own notes. While your doctor will be paying close attention to your baby's growth, it's smart to keep your own written records. It's a good way to catch anything unusual early. You'll also like being able to look back and see how far you've come.

Team up with your child's medical team. Preemies need extra care, especially in their first few years. The best way to make sure your baby is on track is to keep regular appointments with your child's doctor and other specialists. They can catch any issues as they develop, so your baby can get the care they need.

Get help if you need it. Talk to your child's doctor about a state program called Early Intervention. It offers special services to help babies and toddlers (up to age 3) with a higher risk of developmental delays or disabilities. Ask your doctor if there is a need for speech therapy, physical therapy, or occupational therapy.

Show Sources


California Childcare Health Program: "What to Expect from a Preemie in the First Year."

Zaichkin, J. Understanding the NICU: What Parents of Preemies and Other Hospitalized Newborns Need to Know, American Academy of Pediatrics, 2017.

About Kids Health: "About Premature Babies."

Mayo Clinic: "Premature Birth."

UpToDate: "Incidence and mortality of the preterm infant."

Emory University School of Medicine: "Exceptions to Developmental Milestones: Two to Five Month."

March of Dimes: "Developmental Milestones for Baby." "Preemie Milestones."

KidsHealth: "Taking Your Preemie Home."

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