How Long Is A Baby A Newborn?

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The first days after having a baby are a blur for everyone. Between recovering from labor and delivery, meeting the numerous needs of a new baby, and adjusting to the changing family dynamics, it can feel like this stage lasts forever. 

Many parents find themselves wondering when things might calm down. Often, people will tell you that the newborn stage is challenging but fast. 

Unfortunately, when you’re living it, it doesn’t feel like it’s going quickly. A friend once described this stage to me as “5 minutes. Underwater.”

So really, how long is a baby a newborn? How do you know when you’re through that first season? 

The answer isn’t as straightforward as you would think. 

Differing Opinions

My first inclination is always to head to the dictionary, but Merriam Webster is no real help here. The dictionary defines a newborn as a baby who is “recently born.” What’s recently? Great question. The search for an answer continues. 

Some people consider size to be an important indicator of stages; however, babies vary significantly in size at birth. Many babies never even fit into newborn sized clothing!

The World Health Organization defines the newborn stage as lasting from birth to 28 days. This is a particular timeline, and it’s nice to have such a tidy definition. But this definition leaves out some factors such as premature birth or sickness that can affect an infant’s growth development. 

My favorite answer to the newborn question actually lies with each infant’s development. 


Based on the developmental milestones set out by the American Academy of Pediatrics, there are six stages newborns go through. 

Each baby is different, and there is a wide range of timelines associated with each stage.

Stage 1

The initial stage is most often covered in the first seven days of a baby’s life. In addition to spending a significant amount of time asleep (16-18 hours a day), brand new babies will exhibit a variety of reflexes with which they are born.


Parents learn to recognize this reflex quickly because it’s key to helping a baby nurse or bottle feed. When you touch the corner of your baby’s mouth, he will turn his head and open his mouth to follow in the direction of the stroking. This can help your baby find the breast or bottle nipple when it’s time to feed.

baby sucking pacifier


Once your baby’s mouth is open, she needs to suck! Babies are born with the sucking reflex as well, and you can trigger that reflex by touching the roof of her mouth with the nipple or pacifier


The Moro, or startle, reflex causes a baby to throw back her head and then pull her limbs into her body. It often occurs when the baby is surprised by a sound or movement. Babies are easy to startle, and their own cry can trigger this reflex.  


The tonic reflex is when a baby’s head is turned to one side, and the arm on that side stretches out. The opposite arm bends up at the elbow, placing the baby’s hand (or first) near his chin.


Check your baby’s stepping reflex by holding them up (don’t forget to support their sweet little head!) with their feet touching a solid surface. Their legs will appear to take steps or dance. 

Grasp and Babinski

This is my favorite because it seems so sweet and innocent. If you stroke the palm of a baby’s hand, she will close her fingers in a grasp. The Babinski reflex is similar, occurring when you stroke the bottom of her foot to make the toes curl.

Stage 2

The second newborn stage, often in weeks two and three, is when your baby starts to build up their muscles. 

Babies in this stage can lift their heads very briefly while lying on their stomach. They can also move both their arms and legs. 

During this time, a baby’s eyesight is still blurry, but objects and faces closer than ten inches become clear. This clarity allows your baby to identify familiar faces and gestures. 

Stage 3

Stage 3 finds babies continuing to lift their heads when on their belly, but holding it for a few seconds. This is when tummy time should start in earnest so that babies can develop and strengthen their neck muscles. 

Often, babies will begin playing with their pacifiers at this stage and may sleep slightly less, 15-18 hours of sleep a day. 

Stage 4

Most often, babies hit this stage between four and six weeks old. They begin focusing more on faces and can clearly see objects up to 15 inches away. 

This is also a happy time for new parents. You might catch a glimpse of your little one’s precious smile. After you’ve captured a million pictures of his smile, make sure to get a little bit of video to record the coos that he makes. 

Stage 5

While seeing your baby smile is a joyful moment, having them return your smile will also make your day. This happens during the fifth newborn stage, often during the second and third month. 

The time period also marks when your baby may begin to cry a little less in favor of trying out some fun new sounds. Babies in this stage begin to mimic vocalizations they hear around them, so their repertoire of sounds increases. 

Another hallmark of this stage comes with tracking. Your little one will be able to focus on an object and track it as it moves. I always loved watching my babies follow my wiggling fingers. 

You might also notice a little more wakefulness during the day, as babies in this stage sleep for about 14-16 hours.

laughing newborn baby

Stage 6

In this last of the newborn stages, your baby seems to grow up so much. 

Suddenly, they will be able to laugh and squeal and lift their head and chest to a 45-degree angle. 

At this age, you will also find your baby starts rolling over and reaching for objects. 

Even with all this activity, sleep patterns will change as they begin to need less and less sleep. 

Once your little one meets all these milestones, you can claim survival of the newborn stage. 

Premature Babies

Premature babies are infants born before 37 weeks gestational age. These babies often have some catching up to do because they didn’t get to develop before birth fully. As a result, you may hear preemie parents refer to their child’s adjusted age, which takes into account how early they were born. 

Preemies don’t have some of the reflexes, such as the sucking reflex, that full-term babies are born with, leading to more difficulty feeding and gaining weight from the get-go. 

Early babies often need more sleep than their counterparts. The extra rest helps them grow and make those additional developmental leaps. 

Promote Development

Parents can help promote their baby’s development, especially in the newborn stage, in several ways. 

Holding Your Baby

Babies love to be held, and it is a surefire way for your baby to feel safe and secure. That security will allow your baby to make more of the neural connections which lead to those developmental milestones. 

Talking to Your Baby

It may feel weird to talk to your baby, but the more words and sounds a newborn hears, the more they learn. Consider speaking to your baby as a one-way conversation. I used to describe what I was doing while cooking dinner while my babies watched from their bouncers. It’s definitely awkward at first, but worth it!

Change Positions

Putting your baby in different positions helps strengthen and develop tiny muscles. Even when you hold your baby, you can use a cradle hold, a football hold, face them outward, or inward, the list goes on and on. Definitely find positions that make you and your baby comfortable, but try to keep changing it up to help them grow. 

Respond to Your Baby

Babies are exhausting, but they need you! Respond to your baby’s cries and coos. Even if you don’t pick them up every time they fuss, you can use soothing words, a pat on the back, or bounce their chair to let them know you heard them and care. It will increase your baby’s security and build their confidence. 


If you use developmental milestones, the length of the newborn phase will vary on a case by case basis, and that’s ok. 

When it comes right down to it, it doesn’t actually matter when your baby is no longer a newborn. In fact, it’s unlikely you will note the exact moment you move out of the stage. Most parents will wake up one day and realize that their child is suddenly different. 

Take a moment to mourn the stage of newborn snuggles, and then enjoy the next phase of your child’s life.

Emily is a former language arts teacher, turned professional stylist and freelance writer. She and her husband are high school sweethearts, raising their three boys in the same neighborhood where they grew up. In her free time, Emily enjoys running, baking, and singing along to Broadway soundtracks.