Your 4-Week-Old Baby’s Development

Major milestones and everyday tips for your baby at 4 weeks

At 4 weeks, your baby is almost a month old and you've both gone through an enormous amount of change in a very short period of time. Before you do anything else, give yourself a pat on the back for making it this far and recognize all that you have accomplished since you met your little one.

You’ve made it through sleepless nights, struggled through feedings, and learned to do pretty much any task one-handed. But just like every new week so far, there’s plenty more in store for both of you! Here’s what you need to know about your 4-week-old baby.

4-week old baby milestones and development
 Illustration by Joshua Seong, Verywell

Must Knows

  • Be confident in your choices to keep your baby safe and healthy by following current safety recommendations instead of outdated “advice” about infant care.
  • Keep any siblings involved in caring for the new family member as you settle into a new routine.
  • Continue to monitor your little one for colic or reflux with feedings, as both can appear at this time.
  • Congratulate yourself on everything that you and your baby have learned together this month!

Your Growing Baby

Now that your baby is getting a little older, your doctor will measure them against their own growth curve, depending on how old they were when they were born and their weight and length at the time. This allows the doctor to make sure they are still developing appropriately but acknowledges that development among babies can be different.

If your little one was premature, for example, they may be growing differently than a full-term infant. By one-month-old, most infants will have gained about five to seven ounces a week from the birth weight and grown about an inch.

Developmental Milestones

The CDC does not begin tracking developmental milestones for babies until they reach 2 months old because development during the newborn stage can vary. Some babies will develop a little faster than others and some babies may need time to “catch up.” At 4 weeks old, your baby might be able to:


  • Hold their head up for a few minutes
  • Lift hands toward the face or mouth, but it won’t be long before they reach their mouth!
  • Control more head movement, like turning the neck from side to side
  • Make jerky, quivering arm thrusts
  • Keep hands in tight fists
  • Continue strong reflex movements


  • Recognize you, your partner, or family members with widened eyes or signs of excitement
  • See more clearly, up to about 18 inches in front of them
  • Listen intently when you speak or sing
  • Start to coo
  • May turn toward familiar sounds, including your voice. Hearing is fully developed at this stage.
  • Study human faces

When to Be Concerned

Because babies can develop so differently at this age, it’s important to give your little one time to grow at their own pace. However, the American Academy of Pediatrics (AAP) notes that if your baby displays any of the following symptoms, you should consult with your baby’s doctor for additional evaluation:

  • Has poor feeding and/or sucking abilities
  • Doesn’t blink in bright lights
  • Can’t follow a moving object from side to side
  • Is unable to focus eyes
  • Doesn’t move arms or legs, or appears “stiff”
  • Has “floppy” limbs or seems excessively loose
  • Trembles in the lower jar
  • Does not respond to loud sounds at all

A Tip From Verywell

Babies develop differently at this age, and it's important to give your little one time to grow at their own pace.

A Day in the Life

If you have other children, four weeks might be the time where you to start to experience some sibling rivalry. Why? Well, the “newness” of the newborn stage has worn off and the baby is most likely demanding more and more attention, which might mean a little less time for the other kids.

As a family, you might all also be getting back into your normal routine, which now includes a whole other person, so adjustments may need to be made. Here are some ways to help prevent and decrease sibling rivalry:

  • Have your kids help in age-appropriate ways, such as holding the baby, getting diapers, and putting clothes away.
  • Be prepared for changes and regression in your child's behavior and development, such as having more temper tantrums or reverting to accidents if recently potty trained.
  • Encourage friends and family to spend time with your other kids when they offer to help with the baby, or let them help with the baby so that you have more time for your other children.
  • Stick to your usual routines as much as possible, including mealtimes, naps, and bedtimes.

Baby Care Basics

By four weeks, chances are you’ve become a diaper-changing pro! Whether you are using cloth diapers or disposable diapers, your little one may start experiencing a diaper rash from time to time, especially during the summer months. To help prevent and treat diaper rash:

  • Change your baby’s diaper more frequently: Aim for every feeding during the night and as soon as you notice it is wet or soiled during the day.
  • Use a diaper rash cream: You can apply a diaper rash cream as a preventive measure, especially if your baby is prone to getting rashes, if you know your little one will be spending a long day outside, or when you’re traveling. If you’re using cloth diapers, most brands cannot be used with diaper rash cream, so check the tag for instructions before you apply anything.
  • Air it out: The best way to prevent and treat diaper rash is to let your baby go all-natural. Spread a blanket out on the ground and let your baby enjoy some fresh air between changes or after bath time.

If your baby seems excessively uncomfortable, especially after a feeding, they may be experiencing gas. Try these helpful tips:

  • Burp after feedings: Be sure to burp your baby from the bottom upward to facilitate the air movement.
  • Switching formulas: Your infant may need to change formulas several times before finding one that works best for their digestive system. You can try a gentle formula or ask your doctor for recommendations.
  • Change bottles: Bottles and nipples are all made differently, so it might be helpful to try several types of bottles and nipples that have different kinds of airflow to experiment with what reduces gas in your little one.

Feeding & Nutrition

At four weeks old, you should be able to tell if your little one is getting enough to eat by how well they are gaining weight. Your baby should be gaining about half an ounce or even one full ounce of weight every single day.

With breastfeeding, it’s hard to know exactly how much milk your baby is consuming, so, instead, track the length of each feeding and monitor how well your baby is emptying the breast.

Formula-fed babies will eat approximately three to four ounces per feeding at this stage and steadily increase that amount by about one ounce per month until they reach eight ounces. Remember to let your baby lead the feedings and never force your baby to finish a bottle.

Typically, at this age, your baby will still eat about eight to 12 times per 24 hours, continue to soak at least six diapers a day, and have one to three dirty diapers per day as well.

If you’re pumping breast milk for storage, you may wonder how long you can safely store it. The common breastmilk storage guidelines state that breastmilk can be safely stored for the following timeframes:

  • Four to six hours at room temperature
  • Up to 24 in a cooler with ice packs
  • Five to eight days in the refrigerator
  • Two weeks in the freezer (if the freezer compartment is inside the refrigerator)
  • Three to four months in the freezer (a separate freezer compartment)
  • Six to 12 months in a deep freezer

At this age, your baby might attempt to reach or hold a bottle but isn’t able to clutch things just yet, so you may be tempted to prop up a bottle during feeding time. However, the AAP advises parents not to do so, as it can pose a safety risk to babies, induce overfeeding, and may increase the risk of dental problems later in life.

To make breastfeeding and feeding more comfortable for you, use a breastfeeding pillow to hold your baby, but never leave them unattended during a feeding.


At this age, most infants are still not sleeping through the night. Typically, most 4-week-old babies will sleep for 16-18 hours per 24-hour cycle, with several naps during the day and one or two longer “stretches” at night.

As long as your baby is gaining weight well and there are no other medical issues, you can let your little one sleep as long as they want so you can both get the rest you need.

Although SIDS is still a concern for many parents at this age, the AAP currently advises parents not to use any at-home cardiopulmonary monitors, as there is not enough evidence to support their use. The AAP recommends parents room-share but not bed-share for at least six months.

Room-sharing allows you to be able to visualize your baby when he or she is sleeping, know if there is a problem, and intervene as necessary. When you’re not in the room with your baby, you can use a video monitor to keep an eye on your baby.

Health & Safety

At 4 weeks old, your baby will have another well-child check-up. At this visit, the pediatrician will evaluate your baby’s growth and development and go over important safety guidelines with you. You can expect to be asked about:

  • Your home environment: If you smoke, you should quit to reduce the risk of SIDS and increase your baby’s health. No smoke or secondhand smoke should be around the baby.
  • Sleeping arrangements: The AAP recommends that families do not co-sleep at all, even for short naps.
  • Car seat safety: At 4 weeks old, your infant should be in a rear-facing infant seat.
  • Vaccines: The second dose of the Hepatitis B vaccine may also be administered at this visit.

Although most signs of colic tend to appear at three weeks of age, it is still possible for colic to develop later. Talk to your doctor if your little one experiences any symptoms such as:

  • Excessive gas
  • Frequent projectile vomiting
  • Crying that lasts longer than two hours
  • Gaining weight but still being very fussy
  • Irritability in the evening hours

Speak to your doctor to make sure there are no other medical issues with your little one. In some cases, reflux can cause symptoms of colic and is treatable. Signs of reflux include:

  • Choking during feedings
  • Refusing feedings
  • Back-arching during or right after feedings
  • Chronic cough
  • Hoarse voice or cry

Myth vs. Reality

As your baby grows, you may encounter a lot of “advice” from family and friends and, unfortunately, some of the advice you will hear will be outdated and potentially dangerous for your baby. Here are a few of the most common old-wives’ myths surrounding baby care, along with current recommendations to keep your little one safe:

Myth: Babies need a lot of layers to stay warm!

Reality: Overheating and loose layers are both high-risk factors for SIDS, so it’s important to keep your little one safe by keeping them at a comfortable temperature and never having loose layers, including clothing, blankets, or hats with strings near them.

A good general rule of thumb is that if you’re comfortable, your baby will be too. And if you don’t already, you may even want to consider adding a fan to your baby’s room when they sleep, as fan use in the bedroom has been associated with a decreased risk of SIDS.

Myth: Babies need lots of water to stay healthy!

Reality: Breast milk is complete nutrition for the first year of life. Breastfed and formula-fed babies do not need any additional water for the first six months of life as it may replace a feeding and lead to your infant missing out on key nutrients they need to grow.

Myth: You’ll spoil your baby by holding her so much!

Reality: It's not possible. At this age, babies still need you to help them learn about the world, respond to their needs, and make them feel safe.

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