How Preemie Senses Develop - Sight, Vision, Hearing, Taste and Touch

Your preemie's senses, week by week

Preemie Senses Week by Week
Mike Kemp/Getty Images

Do you ever wonder "What can my preemie see? What can my preemie hear?" Babies born prematurely seem so fragile and so tiny, and yet we instinctively hope to connect with them.

In order to do that, it helps to know what's unique about preemies and their senses. Every baby is unique, and develops on his own time schedule. But many developmental milestones  depend on the gestational age of your baby. 

Let's take a look at how the five senses develop in babies - Touch, Hearing, Taste, Smell and Vision.

Keep in mind - all of the following descriptions of preemie behaviors and abilities are estimates - not every baby will develop at the same rate. Some develop more slowly, some more rapidly.

Before we get started with each individual sense, let's take a look at the overall behaviors and abilities of babies at the different stages of development.

General Behaviors at 22-25 weeks

Preemies between 22-25 weeks sleep almost all the time, and they need assistance with breathing, temperature regulation and much more. Babies of this age have very little muscle tone, and they can only move their arms and legs slightly, with uncoordinated, fluttering motion.

General Behaviors at 26-27 weeks

Babies are still sleeping most of the time, with a bit more deep sleep noticeable. Movement is still very uncoordinated and weak, so they rely on their caregivers to reposition them to keep them comfortable.

General Behaviors at 28-29 weeks

Many babies at this age will begin to have REM sleep, which is a time for your preemie’s brain to create connections with his eyes.  Muscle strength will increase, and babies begin to have the coordination and strength to grasp with their fingers. So placing your finger in his palm may cause a weak grasp at this age. 

General Behaviors at 30-31 weeks

Sleep is cycling between light sleep and awake times. Muscle tone is continuing to strengthen, with the ability to move in a more coordinated manner. 

General Behaviors at 32-33 weeks

Awake times are becoming more mature, with a baby having the ability to stay awake and alert for several minutes. He can now turn his head to the side, too, which is quite an accomplishment outside of the womb! This is a part of the important feeding reflexes (rooting reflex) which allows a baby to turn towards a touch on the cheek and the smell of milk.

General Behaviors at 34-35 weeks

Babies at this age are waking more often, and staying awake longer. Movements are more coordinated and strong. Some babies born at this age will require help with their breathing while others will not.

General Behaviors at 36+

This is the first time we see very deep sleep. 36 weekers will generally be very similar in nervous system development and reflexes to full term babies, just slightly less developed. Movement, too, is similar to full term babies although slightly less coordinated. Although they are much like their full-term counterparts, preemies at this age may still lack stamina for feeding and they may require some assistance with their breathing.

For More information regarding the development of senses in your preemie, read Preemies - Second Edition by Linden, Paroli and Doron.

How the Sense of Touch Develops in Premature Babies

Sense of Touch in Premature Babies
Preemie Touch, Week by Week. lemonadelucy/Getty Images

This is the first sense to develop in the preemie, but there are many changes to how a preemie tolerated touch throughout the developmental ages. And it is one of the most powerful senses, because very little calms a baby more than comforting touch.

Touch at 22-25 weeks

The sense of touch is already fairly well developed and your baby knows when she is being touched. Her skin may be translucent, it is very thin, and it’s also very sensitive to touch. In fact, because pain receptors are not fully developed yet, stroking or touching the skin may be perceived as painful to your preemie. At this gestational age, the type of touch they are most comfortable with is a gentle pressure, much like the sensation of the womb around her before she was born.

Touch at 26-27 weeks

A preemie’s skin is becoming less sensitive and less translucent. The type of touch that is most calming at this age continues to be a steady pressure (like the boundaries that a womb creates) rather than stroking or rubbing. Most babies at this age can tolerate skin-to-skin holding - also called kangaroo care, if the rest of their medical issues are stable. (And most parents LOVE it!)

Touch at 28-29 weeks

Skin continues to thicken, appearing more like “normal” baby skin, and becomes even more tolerant of being touched. But it's not unusual for preemies to have skin that is pale, and may also be “mottled” which means the veins just below the skin are visible through the pale skin.

Touch at 30-31 weeks

While many NICU's are reluctant to introduce infant massage too early, because it can overwhelm the infant with too much stimulation, it may be possible to start very slowly and gently during these early weeks.  Research shows positive effects on weight gain, decreased duration of NICU stays, and more positive effects. But infant massage, particularly for preemies, is not what most people typically think of as massage. It's something you have to learn, and always be sure to check with your doctor and nurses before starting infant massage.

Touch at 32-33 weeks

Babies still enjoy the kind of touch that keeps them in a womb-like position, which means containing touch and swaddling continue to provide comfort. Even though your preemie may be big enough for clothes to wear, don't forget how beneficial skin-to-skin touch is for your baby.

Touch at 34-35 weeks

Skin-to-skin touch, as well as the containing touch of swaddling blankets continue to keep preemies at this age happy.

Touch at 36+ weeks

The sense of touch is now quite similar to that of a full term baby. And it continues to be one of the most important ways to connect with your baby.

How Hearing Develops in Premature Babies

Sense of Hearing in Premature Babies
Preemie Hearing, Week by Week. casenbina/Getty Images

Hearing is one of the more straightforward senses in preemies, because ears and auditory organs are completely formed by about 20 weeks. Whether you are a preemie's mother, father, partner or close companion to the birth mother, if your voice has been around the baby while in the womb, she is familiar with your voice and can recognize familiar sounds.

Hearing at 22-25 weeks

Your baby's hearing organs may be fully developed at this point, but she is very sensitive and delicate in many ways. Your baby is familiar with your voice, and she will likely be comforted by hearing you. Even if it's just hearing your voice as you talk with the nurses at the bedside, it's a sound that means safety and nurturing to your little one and it's great for her to hear you.

Hearing at 26-27 weeks

It's often during these weeks that you'll first see your preemie clearly respond to your voice. Whether by turning her head slightly towards you, or merely opening her eyes when she hears you, it's a wonderful thing to see you little one recognize your voice.

She won't be able to stay awake long, or look right at you when you speak, but she's still comforted by hearing your familiar voice.

Hearing at 28-29 weeks

A great way to bond with your baby through hearing is during kangaroo care time. When you are holding your baby skin to skin, it's a great time to gently talk to your baby and sing lullabies. Try to make sure your baby continues to know your voice as a most familiar one. 

Hearing at 30-31 weeks

Another way to keep the sound of your voice as a comforting presence for your baby is to read books aloud to your baby. Here's a list of books that are great read-aloud books for preemies. Even on a day when you can't touch your baby, you should be able to sit beside the isolette and read to your baby.

Hearing at 32-33 weeks

Not much change is occurring during these weeks, because your baby can still hear quite well, although not very soft whispers. Keep singing, reading, and talking to your baby.

Hearing at 34-35 weeks

By this age, babies most likely can hear softer sounds such as whispers, and hearing is nearly fully formed.

Hearing at 36+ weeks

Your baby's hearing is essentially the same as a full term baby's hearing, and she can hear quite well. Let her hear her favorite thing - you!

Your baby should have a hearing test before going home - the Joint Committee on Infant Hearing recommends every baby who has spent more than 5 days in the NICU have a hearing screen prior to discharge.

A couple of notes about hearing -

For the times you are apart, consider leaving a recording of your voice. Nurses can play the sounds of you reading, singing lullabies, or just talking to your baby. It's a great way to keep the sound of your voice a constant in your baby's life.

And if you are adoptive parents, and your baby isn't yet familiar with your voice, fear not. Preemies adapt quickly, and you can start as soon as you get to start spending time with your baby. When your voice is associated with cuddle time, comforting touch, feedings, and the other nurturing that you provide when you're with your baby, she'll quickly respond to and enjoy the sound of you.

How the Sense of Taste Develops in Premature Babies

Sense of Taste in Premature Babies
Preemie Taste, Week by Week. Todd Bates/Getty Images

The sense of taste is fully formed around 21 weeks gestation, so it’s one of the most wonderful ways to actually be able to connect with your baby when she’s born prematurely.

Since it's already developed at birth, let's look at appropriate ways to connect with your baby with her sense of taste rather than breaking it down week by week.

Fetuses begin swallowing amniotic fluid at 12 weeks, and can begin to taste it around 15 weeks. Amniotic fluid has complex flavors, including sour, salty and sweet. 

When babies are born early, they lose that constant exposure to the tastes in the amniotic fluid, which are replaced with the tastes and sensations of NICU equipment such as feeding tubes and ventilator tubes in the mouth, pacifiers, breast milk, and sucrose drops.

What tastes to all babies seem to prefer? Their mother's breast milk, followed by donor breast milk and formula.

Babies definitely do like sweet - in fact, sucrose (sugar) drops are used because they are a non-invasive way to provide pain relief. Babies who receive small amounts of sucrose before painful procedures exhibit less painful responses, so it's a wonderful way to take advantage of the developed sense of taste.

While pacifiers don't have a taste, per se, they do provide a wonderful mouth-centered comfort to babies. By providing opportunities to suck on a pacifier, even when intubated, your baby is experiencing positive, pleasant sensations with her mouth, which will help her enjoy experiences such as eating and drinking as she grows.

Oral aversion - the dislike of anything in the mouth - is a big concern that NICUs are very aware of. When preemies have nothing but unpleasant experiences around their mouth, including long-term intubation and unpleasant oral suctioning, they may grow to dislike having anything in or near their mouths. NICUs do their best to avoid this in many ways:

  • a few drops of expressed breast milk in your baby's mouth, even if your baby is not officially eating, because it is very comforting to babies.
  • pacifiers provide very positive experiences for babies, even when they are intubated.
  • Sucrose drops are used to decrease pain responses, and this is another pleasant experience for babies.

[Reference: Prenatal and Postnatal Flavor Learning by Human Infants]

How the Sense of Smell Develops in Premature Babies

Sense of Smell in Premature Babies
Preemie Sense of Smell, Week by Week. Steve Ogle/Getty Images

Smell at 22-25 weeks

Fetuses in the womb begin early breathing movements around 22 weeks, which causes amniotic fluid to pass in and out of the nostrils, and this likely starts the sense of smell development. So while smell is not fully formed at this time, babies at this age are likely beginning to recognize familiar scents.

Smell at 26-27 weeks

Smell is continuing to develop, and a wonderful way to share comforting smells with a baby who has been born early is by allowing them to smell his parents is through holding. While the sense of smell isn't yet fully developed, it's developing, and it's great to keep your baby familiar with your comforting smell.

Smell at 28-29 weeks

This is roughly the stage when the sense of smell fully develops. Babies show a preference for the smell of their mother and their mother's milk over other smells.

Smell at 30-31 weeks

The smell of breast milk will now be associated with digestion and will help stimulate digestion. Many NICU's will place a few drops of milk on a pacifier, which allows the baby to taste and smell the milk, using those senses to connect the comfort of food and the process of digestion.

Smell at 32-33 weeks

Is your nurse putting a drop of milk on the pacifier? Babies suck stronger and longer when they have the taste they love the most. Or try one of these cute blankets to share your smell with your baby while you're apart.

Smell at 34-35 weeks

Another great way to connect with your baby through his sense of smell at this age is to ask your nurse for a blanket that you can wear next to your skin and then leave with your baby. This scent-filled cloth will leave a powerfully comforting smell for your baby, and give you a greater sense of staying connected. (And you can also use your sense of smell to stay connected too - ask for a blanket that your baby has been wrapped in to take home - you'll love breathing in the smell of your sweet baby.)

Smell at 36+ weeks

By now your baby's sense of smell is much like a full-term baby. Your preemie will continue to prefer the smells of familiar people and milks.

How Sight Develops in Premature Babies

Sense of Sight in Premature Babies
Preemie Sight, Week by Week. Getty Images

Vision is the last of the senses to develop completely, in fact it's not fully developed for months after full-term.

Vision at 22-25 weeks

A baby's eyes start out fused at this age, but eyebrows and eyelashes are present. Within this window of time, your baby may begin to open her eyes for the very first time. When she does open her eyes, she will be very sensitive to light. Blankets over incubators and dim lights in the NICU when possible are helpful for protecting her delicate and sensitive eyes.

Vision at 26-27 weeks

Babies at this age may open their eyes occasionally, but usually only for very brief amounts of time, and rarely in the presence of bright lights.  They can most likely only perceive patches of light and dark, and will keep their eyes shut most of the time, even when activities such as diaper changes and repositioning happen.

Vision at 28-29 weeks

Babies this age will still not keep their eyes open for very long, although they're open a little more every week. What they are seeing is still very fuzzy areas of light and dark without much definition.  And the eyes may cross or be out of sync with each other, but this remains normal even past full term. For these weeks, continue to focus your attention on the senses that are more fully developed as a way to connect.

One complication of prematurity is ROP, a condition where the growth of the retnia is altered because of preterm birth. Your preemie will most likely have eye exams to check for this starting between 4-8 weeks after birth.

Vision at 30-31 weeks

Babies now can begin to focus, particularly on bold simple patterns. Faces and darkly contrasting images hold their attention better than anything else. You'll see your preemie opening her eyes when she's comfortable & relaxed, and she'll even start to look around a little more.

Vision at 32-35 weeks

Research shows that by this age, babies will look longer at some patterns more than others, showing early signs of preferring certain visual images. The images they seem to prefer are usually ones at a distance of 8-12 inches from her eyes.

Vision at 36+ weeks

Vision is now approaching full-term vision, which means babies can focus on images that are near (even full term infants are near-sighted) and they can hold their gaze for longer than before. Babies this age will still have uncoordinated eye movements and may cross their eyes, which is normal.  

Whether your preemie had vision screenings or not during her NICU stay, it's important to have her vision checked as she grows. The InfantSEE program recommends every baby have a vision check by 6 months of age.

For more information about complications of vision related to preterm birth, read more here.

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