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

Here's everything you need to know about your newborn's development, from feeding to sleeping and even pooping.

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

Your baby is becoming more alert, and really starting to feel like a little person. With that heightened alertness, though, comes more intense periods of fussiness, which could be 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 making eye contact more often.
  • Sleep: Your baby spends the majority of their time sleeping, but may be progressing toward some longer stretches of sleep at night.
  • Food: Your baby is feeding frequently, and needs to be fed at night.
3-week-old baby growth and development

Illustration by Joshua Seong, Parents

3-Week-Old Baby Development

Your 3-week-old baby is more awake and alert than ever. As pediatrician Natasha Burgert, MD, explains, 3-week-olds still sleep a lot, but they generally seem more aware and responsive to their environment.

If you are lucky, you even get a few sweet moments where your baby locks eyes with you. “There may be some slight eye contact, but visual engagement is still developing,” says Dr. Burgert. At this age, babies can only clearly see about 8-12 inches away.

As your baby develops more personality, they will experience more cranky moments. “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.” Ensuring a good latch while breastfeeding can help, so that your baby doesn’t swallow too much air.

Many babies start to develop colic, or periods of inconsolable crying, that be very stressful. One in five babies have colic, and it usually peaks between 4 and 6 weeks.

Colic usually gets better within a few weeks. Rocking, shushing, walking, and letting your baby suck on a pacifier can help. If your baby’s tummy seems upset, talk to their pediatrician. Some babies are sensitive to ingredients in formula or to something their breastfeeding parent is eating.

3-Week-Old Baby Milestones

Your baby is getting stronger every day and their body movements may seem more coordinated. “When moving around, they should be moving their arms and legs equally,” Dr. Burgert says.

With this added strength, your baby has a little bit more neck and head control, explains Amy Verlsteffen, APRN, senior director of clinical transformation at TytoCare. At this age, many babies are able to lift their heads about 45 degrees during tummy time.

Don’t worry if your baby still can’t do that, though. “Tummy time will help the baby's head and neck become stronger and prevent flattening of the back of the head,” Verlsteffen says.

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

Additional Behaviors

  • Your baby’s hearing is fully developed. 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.
  • Your baby may begin moving their head side to side during tummy time.

3-Week-Old Baby Feeding

Your baby should be back to their birth weight and steadily gaining weight. Babies of this age gain about one ounce a day. Your baby will still be feeding very frequently, though gaps between feedings may start to stretch out.

You should still practice “responsive feeding,” feeding your baby when they show hunger cues until they show signs they are full. Many parents and babies will get into a rhythm with feedings, but 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,” says Verlsteffen. “Feeding issues at 3 weeks of age should be discussed with a lactation consultant or the baby’s pediatrician.”

Your baby is really starting to grow, and their newborn clothes may be getting snug. 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.

The biggest feeding concern is probably gas, which can trigger more crying and perhaps the emergence of colicky symptoms.

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. 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 gassy tummy include making sure not to overfeed your baby, burping your baby frequently, or gently massaging their back.

3-Week-Old Baby Sleep

Your baby is still sleeping a whole lot, 14-17 hours a day on average. 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. But babies this age are still eating very frequently, or cluster feeding, 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."

Babies at this age still don’t know the difference between night and day, says Verlsteffen. But 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. Keep your curtains open and the lights on during the day, and keep things dim at night. Over the next few weeks, your baby should adjust, Verlsteffen assures.

3-Week-Old Baby Schedule

At this age, 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 it. Place your baby on a baby play mat and give them a chance to freely move and engage.

Another favorite activity to do with your baby 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 gas relief. Ask your pediatrician, but some doctors recommend gripe water or gas drops, over-the-counter treatments that help with both gas and reflux.

Swaddling

Because of the uptick in fussiness, many parents try swaddling their babies to soothe them. This generally works well, but 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. 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, blowouts!), 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. If there are any signs of infection, such as redness or swelling, contact your doctor right away.

Uncircumcised penises don’t require any special care. 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. Your baby’s foreskin will naturally retract by about age five.

Clogged Tear Ducts

Your baby’s tear ducts are maturing and may become blocked. You might notice that their eyes are more red or watery than usual or that a crust has accumulated. Usually, these clear up on their own, but you can apply a warm, wet cloth on the eye to soothe it.

Baby Skin Issues

Your baby may have a case of “baby acne,” and some develop “cradle cap,” or scaly patches on the scalp.

Neither of these are cause for alarm and you don’t have to do anything to treat them. But 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 cradle cap. Gently massage away the scale when shampooing your baby's head. For more stuck-on cradle cap scale, use a non-food-based oil (like baby oil) to soften the scale and make it easier to remove. Apply the baby oil to the scalp before bathing, then shampoo while gently massaging the scale with your fingers. You can also carefully use a baby brush during your baby's bath to remove the scale in their hair. Never scratch or pick at cradle cap, as this could cause an infection.

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

If you notice a spike in crying at this time, remind yourself that this is normal, and will pass eventually. If nothing you are doing is helping soothe your baby, reach out to your pediatrician for advice. Babies cry to communicate, so try to feeding, changing, burping, and soothing. If the crying is prolonged or prolific, this could signal something bigger, perhaps a medical issue, so always go with your instinct and contact your pediatrician as necessary.

Key Takeaways About Your 3-Week-Old Baby

Your baby’s third week of life is a very exciting time. You are still in the thick of the newborn period, and it can also be a draining and overwhelming 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 okay to place them in a secure spot, and leave the room for a minute to regroup.

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

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Sources
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