Your 3-Week-Old Baby’s Milestones & Development

At 3 weeks, many parents are starting to feel like they are getting into the groove of caring for their baby. They understand better what their baby needs, and are starting to adapt to the lifestyle of parenting a newborn—exhaustion and all!

What’s more, your baby is becoming more and more alert, and really starting to feel like a little person. With that heightened alertness, though, comes more intense periods of fussiness, and some babies are even beginning to show signs of colic.

Here’s what you need to know about parenting a 3-week-old baby, including what milestones to look forward to, some care and safety tips to keep in mind, and what to expect when it comes to feeding and sleep.

At This Age

  • Development: Your baby is becoming aware of their surroundings, and may be making eye contact with you more often.
  • Sleep: Your baby still spends the majority of their time sleeping, but may be progressing toward some longer stretches of sleep at night.
  • Food: Your baby is still feeding frequently, and needs to be fed at night; you may notice that your baby is gassier than before.
3-Week-Old Baby
Illustration by Joshua Seong, Verywell

3-Week-Old Baby Development

If you compare your 3-week-old to how they were at birth, you might feel as though you have a completely different baby! As Natasha Burgert, MD, pediatrician and Philips Avent Spokesperson, explains, although 3-week-olds still sleep a lot, they generally have longer periods of awake time. When they are awake and alert, they just generally seem more aware and responsive to their environment.

If you are lucky, you even get a few tiny moments where your baby will lock eyes with you (trust us, it will melt your heart). “There may be some slight glimpses of eye contact, but visual engagement is still developing,” says Dr. Burgert. At this age, babies can still only clearly see about 8-12 inches away.

As your baby develops more of a personality, they will be experiencing more cranky moments. Many parents observe that this coincides with extra tummy issues as well.

“By three weeks, some babies are having more gassy, fussy periods,” Dr. Burgert says. “Any extra air in a baby's stomach can make this discomfort worse,” she says. Ensuring a good latch while breastfeeding can help, Dr. Burgert suggests, so that your baby doesn’t swallow too much air.

Three weeks is also the time that many babies start to develop colic or colicky symptoms. One in five babies develop colic, and it usually peaks for babies between 4 and 6 weeks of age. Colic usually involves periods of inconsolable crying, usually during the evening, and can be very stressful for parents, especially if they don’t feel like they know how to soothe their babies.

Understanding that colic is common and usually gets better as time goes on can be very reassuring to parents struggling with colicky babies. Rocking, shushing, walking, and letting your baby suck on a pacifier can help. If your baby’s tummy seems upset, you can talk to their pediatrician; some babies are sensitive to ingredients in formula or to something their breastfeeding parent is eating.

Your baby is really starting to grow, and you may notice that their newborn clothes are getting a little more snug. At this point, your baby has started to surpass their birth weight, and is putting on a little weight each day.

Three-week-old babies usually gain about 1 ounce a day, and by the end of their first month, they usually have grown about 1 to 1 ½ inches.

3-Week-Old Baby Milestones

Your baby is getting stronger every day. You might notice that your baby’s body movements seem less random and more coordinated, says Dr. Burgert. “When moving around, they should be moving their arms and legs equally,” she describes.

With this added strength, you may notice that your baby has a little bit more neck and head control, explains Amy Verlsteffen, APRN, senior director of clinical transformation at TytoCare. She says that at this age, many babies are able to lift their heads about 45 degrees when they are lying on their bellies.

Don’t worry if your baby still can’t do that, though. All babies are a little different. Verlsteffen suggests spending a little time each day doing “tummy time” with your baby to help them strengthen their muscles.

“Tummy time will help the baby's head and neck become stronger and prevent flattening of the back of the head,” she says.

At this age, your baby may also begin to follow faces and moving objects with their eyes, says Verlsteffen. This is a skill that is just emerging at this age, but which will get more refined as your baby gets older, and especially as their vision gets sharper. Remember, your baby’s vision is still a little blurry, and they can only see clearly a few inches in front of them.

Additional Behaviors

  • Your baby’s hearing is fully developed at this point, and they should turn their head when they hear a sound.
  • Your baby can smell well and may even recognize the scent of breast milk.
  • Your baby can’t see more than 8-12 inches away but should respond to bright lights in the room or outside.
  • Your baby may begin moving their head side to side during tummy time.

3-Week-Old Baby Food

After losing a little weight in their first week of life, your baby should be back to their birth weight now and starting to steadily gain weight. Generally, babies of this age gain about one ounce a day. To accomplish this, your baby will still be feeding very frequently, though some of their feedings may start to stretch out a little bit.

During this time, you should still practice “responsive feeding” with your baby, feeding them when they show hunger cues, and reading them for signs that they are full. While many parents and babies will get into a rhythm with feedings, there will be a wide variation of feeding patterns at this age.

“They may be cluster feeding more or go longer periods of time between feeds, but you should not be experiencing any regression in their feeding at this stage,” says Verlsteffen. Make sure to reach out for help right away if you are still struggling, Verlsteffen advises.

“Feeding issues at 3 weeks of age should be discussed with a lactation consultant or the baby’s pediatrician,” she says.

Probably the biggest feeding concern parents have at this age is that their baby may seem gassier than before. This gassy period often coincides with periods of more crying, and the emergence of colicky symptoms. Your baby may be particularly gassy at night.

If you are breastfeeding, consider allowing your baby to finish one breast completely before offering the other. This ensures that your baby receives more of your “hindmilk” which is often easier to digest. You can also talk to your pediatrician about whether something you are eating may be upsetting your baby’s tummy. Cow milk products are a common culprit.

Other options for soothing a baby’s gassy tummy include making sure not to overfeed your baby, burping your baby frequently, or gently placing your baby across your knees, and massaging their back.

3-Week-Old Baby Sleep

Your baby is still sleeping a whole lot, 14-17 hours a day on average. At this age, your baby should still be waking up in the middle of the night at least a few times to eat, says Verlsteffen. Some babies may start to sleep longer stretches at night—up to four hours, if you are lucky. But babies this age are still eating very frequently, and unfortunately, that includes at night, she says.

“It is still completely normal for the baby to be waking up frequently in the night to eat and to be changed,” she explains. “You do not want a baby of this age to be sleeping through the night because they will likely be lacking the important nutrition that their body and brain need for development.”

On top of that, babies still don’t know the difference between night and day, says Verlsteffen. But starting now, there are a few things you can do to try to get your baby used to the idea that nighttime is for sleeping and daytime is for being awake.

You can do this by keeping your curtains open and the lights on during the day, and keeping things dim at night. Over the next few weeks, your baby should finally get it, Verlsteffen assures.

3-Week-Old Baby Schedule

At 3-weeks, you should be doing “tummy time” with your baby on a regular basis. The American Academy of Pediatrics (AAP) recommends that you do tummy time 2 to 3 times a day for about 3-5 minutes per time. Tummy time helps strengthen your baby’s muscles but it’s also a wonderful opportunity for you to get down on the floor and interact with your baby.

Try not to overthink tummy time. Just place your baby on a nursery rug, or a baby play mat if you have one. If they fuss, you can try again later. In time, most babies end up enjoying tummy time, because it’s a chance for them to freely move their bodies and engage with their parents.

Another favorite activity to do with your baby at this age is to go out for a walk in a stroller. You can also wear your little one in a baby carrier. Consider going out when your baby is fussy—often, they stop fussing as soon as they get outside.

3-Week-Old Baby Health and Safety

As long as your baby is having multiple wet and poopy diapers a day, and seems generally healthy and content, you don’t need to take your baby to your pediatrician until their one-month check-up, which is just around the corner. That said, if you have any other questions about your baby’s health or well-being, you should always reach out to your pediatrician.

Here are a few other health and safety tips to keep in mind.

Vitamin D Supplements

While breast milk offers fantastic nutrition for your baby, it doesn’t usually contain an adequate amount of vitamin D, and your doctor will likely recommend that you give your baby vitamin D supplements (400 IUs), usually in the form of drops.

Medication for Gas

As babies experience increased gas and tummy upset during this time, many parents want to know if there is any medication they can give their baby for relief. This is a question you should ask your pediatrician, but most doctors recommend simethicone drops, which is an over-the-counter medication that can help with both gas and reflux.

Swaddling

Again, because of the uptick in fussiness during this time, many parents are interested in swaddling their babies as a way to soothe them. This can be very helpful and works well for many babies. However, you want to make sure that you do it safely.

The AAP recommends that you don’t swaddle too tightly around your baby’s hips, to prevent hip dysplasia. You also want to make sure that you put your baby to sleep on their back at all times, including when swaddled.

3-Week-Old Baby Care Basics

Your baby care still revolves most around changing diapers at this point. Besides all the diaper changes (and yes, sometimes whole outfit changes on top of that!), there are a couple other baby care topics to be aware of.

Circumcision

If your baby was circumcised at birth, the circumcision site should be healed and you can continue washing it with soap and water. If there are any signs of infection, such as redness or swelling, you should contact your doctor right away.

Uncircumcised penises don’t require any special care. You can wash your baby’s penis as you do the rest of their body. Importantly, you shouldn’t pull down their foreskin or force it loose in any way. Your baby’s foreskin will naturally retract by about age five.

Clogged Tear Ducts

Your baby’s tear ducts are still maturing and there may be times that they become blocked. When this happens, you might notice that their eyes are more red or watery than usual or that a little crust has accumulated. Usually these clear up on their own, but you can also apply a warm, wet cloth on the eye to soothe it. Gentle massage can help too.

Baby Skin Issues

Your once perfect looking baby may begin to look a little less than perfect this week. Many babies this age develop a case of “baby acne,” and some babies develop “cradle cap,” which is where scaly patches appear on their scalp.

Neither of these issues are cause for alarm and you don’t have to do anything in particular to treat them. However, avoiding harsh soap, not over bathing your baby, and giving your baby some naked time to let their skin air out can be helpful. A baby brush or comb can be used to gently remove your baby’s cradle cap.

What Else to Know About Your 3-Week-Old Baby

If you notice a spike in your baby’s crying at this time, try to remind yourself that this is normal, and will pass eventually. If you feel that nothing you are doing is helping to soothe your baby, don’t hesitate to reach out to your pediatrician for advice. Most crying at this age is “just what babies do,” but sometimes the crying is the cause of a medical issue, so always go with your instinct, and contact your pediatrician if anything doesn’t feel right.

Frequently Asked Questions

  • What does a baby develop at 3 weeks?

    Your baby is starting to develop a heightened awareness of their surroundings, and their head and trunk muscles are becoming stronger.

  • What can a 3-week-old baby see?

    Your baby can still only see a few inches in front of them, and can mostly only make out black and white colors. But they love looking at their parents’ faces.

  • How much do 3-week-old babies sleep?

    Babies still spend the majority of their day asleep, and average about 14-17 hours snoozing.

  • How long should a 3-week-old do tummy time?

    The AAP recommends doing tummy time with your baby 2-3 times a day, for about 3-5 minutes each time.

  • Can babies smile at 3 weeks?

    Your baby’s first social smile won’t be until about two months, but your baby may begin smiling in their sleep at this age, and many parents count these smiles as “real”!

  • How much milk should a 3-week-old drink?

    Formula fed babies drink about 3-4 ounces a feeding at this age. Breastfed babies usually need to feed about 8-12 times in a 24 hour period to ensure adequate milk intake.

  • How do you play with a 3-week-old baby?

    Babies love interacting with their parents, but you don’t need to do anything special to make your baby happy. Holding your baby on your lap and making funny faces will do the trick; you can also engage with your baby when they are on their belly doing tummy time.

A Word From Verywell

Your baby’s third week of life is a very exciting time for everyone involved. But remember that you are still in the thick of the newborn period, and it can be a draining and overwhelming time. This is particularly true if your baby has proven to be extra fussy during this time.

Your baby’s health and well-being are important, but so is yours. If you are finding it difficult to cope with your baby’s crying or fussing, it’s OK to place them in a secure spot, and leave the room for a minute to regroup.

If you are still generally finding it hard to cope with the transition to parenthood, or are experiencing heightened depression or anxiety, please reach out to your healthcare provider. You may be experiencing a postpartum mood disorder. If you are, help is out there, and there are effective treatments that will help you feel like yourself again.

Originally written by
Chaunie Brusie, RN
Chaunie Brusie, RN
Chaunie Brusie is a registered nurse with experience in long-term, critical care, and obstetrical and pediatric nursing.
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22 Sources
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