Preemie Milestones: A Premature Baby Development Week-by-Week Guide

By Claire B. Crompton, RN

Claire is a registered nurse and health writer with a certification in neonatal intensive care nursing. She has years of experience taking care of moms and babies in postpartum and neonatal intensive care units and has taught childbirth education classes to new parents. Find out more at www.clarityhealthwriting.com.

Having a premature baby is an intense experience that can dramatically change your expectations and plans. While every baby reaches their developmental milestones at their own pace, this overview of premature baby development week by week can help you understand what to expect and feel more prepared for your preemie’s journey.

What Are Preemie Baby Milestones?

Preemie developmental milestones are goals your baby will work toward before going home from the neonatal intensive care unit (NICU). Your hospital may have additional discharge goals, in addition to these common milestones for preemies:

• • Regulating their body temperature

• • Breathing effectively

• • Gaining weight

• • Learning how to feed

Even though your baby is being cared for around the clock by highly trained healthcare professionals, being temporarily separated from your baby can be difficult. If you are the one who has given birth, remember to take care of yourself, too. Your well-being is important to your ability to be there for your little one.

What Does Premature Baby Development Week by Week Look Like?

Although being born early can sometimes result in medical complications and temporary setbacks, premature baby development week by week happens in the same general progression as it would in the womb. Some babies reach these developmental milestones earlier, while others need a little more time.

Every preemie’s journey is different, and your baby’s healthcare team will help guide you through each stage.

The Early Weeks of Premature Baby Development: 23 to 32 Weeks Gestation

At 23–26 weeks, your baby may not be able to open their eyes, but their ears are fully formed and they can hear your familiar voice. Their skin is also developing and is quite fragile. The NICU staff will teach you how to gently touch and comfort your baby.

Because they are so small, it is difficult for preemies to regulate their body temperature. Your baby will spend lots of time inside an incubator during these early weeks. This warmed environment helps your baby devote their energy to developing and gaining weight.

Premature babies’ lungs aren’t mature, and they may need medication and oxygen support to help them breathe. They also haven’t fully developed the part of their brain that consistently triggers breaths. This causes 15–20 second pauses in their breathing, known as apnea of prematurity. Your baby’s medical team will monitor their vital signs and provide oxygenation support if needed.

Initially, your baby will receive intravenous (IV) fluids containing the nutrients they need until they are medically stable and ready to start feeding. Even though their digestive system may be ready, your baby has not yet developed the ability to coordinate sucking, swallowing, and breathing. Because they often need help with this preemie milestone, NICU infants may be fed through a tiny, flexible feeding tube that passes through their nose or mouth, down their esophagus, and into their stomach.

Around 26–28 weeks, your baby may be able to open their eyes. Their developing neurological system isn’t able to handle lots of stimulation, such as bright lights or loud sounds. As you spend more time with your baby, you will learn their overstimulation cues and know when they need rest.

If your preemie is medically stable, you may be able to hold them on your chest skin-to-skin, also known as kangaroo care. This can help soothe your baby and stabilize their vital signs, while also providing an important opportunity for bonding. If your medical team recommends it, try to enjoy this time together as much as possible.

By 28–32 weeks, your baby’s tolerance for sensory stimulation will increase, but they can still be easily overwhelmed and may shut their eyes in bright light. You might observe them responding to your voice and maintaining eye contact. As your baby becomes more alert, continuing kangaroo care can facilitate bonding and provide comfort for both you and your baby.

Transitioning Weeks: 33 to 37 Weeks Gestation

Your baby may begin to show feeding cues, such as sticking out their tongue or smacking their lips, around 33–34 weeks. Once the medical team has determined your baby is ready, they can begin working toward one of the more challenging preemie milestones: learning how to feed from the bottle or breast. Patience is essential, because this process takes time.

As your baby grows, their incubator’s temperature will be gradually decreased until it is no longer needed. As long as your baby has achieved the preemie milestones of maintaining adequate weight gain and regulating their body temperature, they can be moved to an open crib.

This is one of the more exciting premature baby milestones because your little one is beginning to experience a sleep environment that more closely resembles the one they’ll have at home. Now they may also be able to be swaddled. Swaddling with plenty of room for your baby’s legs to bend can help support healthy hip development.

The open crib sleeping environment is similar to the one they will have at home, and products such as the Bassinet V3 or Soma Smart Bassinet provide the firm, flat, open surface that they need for safe sleep.

Establishing safe and healthy sleep habits early is an important part of supporting your baby’s development and your family’s well-being.

Typically, around 35 weeks, apnea of prematurity starts to resolve on its own and is not known to cause other health or developmental issues. Once a baby has stopped having these episodes, they will likely never happen again. Your baby’s medical team will continue watching them closely to determine when they have reached this stage of premature baby development.

If your baby is medically stable and their NICU team approves it, they can be entertained and soothed by the Mamaroo Smart Swing. Thanks to its variety of calming sounds and natural motions, the Mamaroo is designed to mimic the movements parents naturally use to comfort their babies.

Nearing Full Term: 37 to 42 Weeks Gestation

Your baby has made huge strides in overcoming the common hurdles of preemie baby development and is getting close to going home.

As they continue to develop, you can expect them to become more social as they explore their environment through touch. Massage can help them develop their sense of touch, along with offering soft toys and smooth fabrics with a variety of textures.

Their vision is continuing to develop, and they may enjoy objects with contrasting colors, such as black and white, although faces are often their favorite things to look at.

Your baby will also enjoy supervised, un-swaddled playtime on a play mat or Remi Bassinet & Playard. Allowing your baby to move freely helps strengthen their muscles and develop their motor skills.

Homecoming and Beyond: 42 Weeks to 3 Months

Bringing your baby home from the NICU is a huge accomplishment and an important transition for your family. After spending so much time surrounded by your baby’s healthcare team, adjusting to home life can bring a mix of excitement and new questions.

You can make the adjustment to home life easier by talking, reading, and singing to your baby. Doing these activities throughout a flexible routine can stimulate their language development, calm them, and give them a sense of security and predictability.

Having your own Mamaroo Smart Swing can also be helpful during the transition to home life. Your baby may enjoy the familiar motions and sounds, while features like Bluetooth and voice control can provide hands-free convenience for parents.

Do NICU Babies Hit Newborn Developmental Milestones Later?

Premature babies’ progression toward their standard developmental milestones is tracked according to their adjusted age.

Adjusted age is calculated by subtracting the number of weeks your baby was born early from their actual age. For example, if your baby was born eight weeks early, their adjusted age will be four months when they are six months old.

You can expect them to have developmental skills similar to a four-month-old baby who was born full-term. Try to keep this in mind when comparing your baby to others of the same chronological age.

How Long Does It Take a Preemie to Catch Up?

Every baby develops at their own pace. Most preemies catch up to the typical milestone range by age 2. If your child doesn’t seem to be on track by this time, their pediatrician can connect you with resources for additional support.

Celebrating Premature Baby Development Week by Week

Supporting your premature baby requires lots of patience. It is helpful to remember that they are very resilient, and you are too.

Your baby will accomplish their preemie milestones in their own time. Having a preemie can be challenging, but you are not alone. The healthcare professionals in the NICU are there to provide guidance and support throughout your journey.

As you love, care for, and support your premature baby, take time to celebrate each milestone they achieve, both in the NICU and beyond. Every step forward is worth celebrating—and every day brings you one step closer to bringing your little one home.