4-Week-Old Baby Development Milestones: What You Should Know

Your little one is a whole month old! At 4 weeks of age, newborns are still quite new to the world and spend the majority of their time sleeping and eating. Around this time, though, they begin to develop a bit more recognition of their environment and start showing a little more coordination in their movements. They’re probably not sleeping through the night yet and may get predictably fussy around the “witching hour,” but they’re also becoming more communicative and alert. Let’s examine some 4-week-old baby developmental milestones and what you can expect when it comes to feeding and sleeping patterns in the coming weeks. 

4-Week-Old Baby Development Milestones

While you’re probably excited to see your one-month-old begin to perk up and show a bit more of their personality, many infants this age continue to spend most of their time sleeping, eating, pooping, and doing little else. Be patient – many changes and milestones are on the horizon in the coming weeks. All little ones develop at their own pace, but around this time, you should begin seeing some significant growth. Starting at about one month, your baby should be gaining about 1 ½ to 2 pounds per month. They should grow about one inch in length per month, and their head circumference should increase by about ½ inch per month.

At 4 weeks old, your newborn is also becoming increasingly responsive to the world around them. Their hearing is fully mature at this age, and you might observe them turning their head toward the sound of your voice. Their vision is still blurry beyond just a foot or so in front of them, but they adore seeing familiar human faces and high-contrast black-and-white patterns.

Frustratingly, this is also the age when many babies begin showing signs of colic or experience the period of PURPLE crying, a stage of persistent, inconsolable crying. While it can be stressful and overwhelming for parents, it’s important to remember that it won’t last forever and is considered a normal part of development in some children. Most infants will grow out of this phase by 3 or 4 months of age, but if you have concerns, speak with your pediatrician.

Supervised tummy time is important at this age, too, and helps little ones build their strength. You’ll probably notice that your baby can now lift their head when lying on their stomach and maybe even move it from side to side. Their overall movements, once shaky and clumsy, become a bit more coordinated and intentional. You may even see them try to put their hands in their mouth. Other 4-week-old baby milestones you may observe may include:

• Keeps hands in tight fists
• Strong reflex movements
• Prefers sweet smells and dislikes bitter or acidic smells
• Recognizes the scent of their own mother’s breastmilk
• Prefers soft to coarse sensations
• Dislikes rough or abrupt handling
• Becomes excited when you speak or start signing

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4-Week-Old Baby Feeding

At 4 weeks, your newborn should have surpassed their birth weight and be gaining more weight steadily. Doctors recommend parents continue to feed their babies responsively and according to their baby’s cues (also known as feeding on demand). Most babies are pretty adept at knowing when they are full and when they are hungry. Breastfed babies still nurse about eight to 12 times a day at this age. For formula-fed infants, start with 2 ounces per feeding and then increase it by an ounce at a time if your baby fusses or seems to want more. Bowel patterns may be less frequent now than when your baby was first born and can be quite variable. Spitting up is also normal as long as your little one isn’t in a lot of pain and is continuing to gain weight. 

4-Week-Old Baby Sleeping

Babies this age still spend much of their time sleeping – around 15 to 16 hours spread pretty evenly throughout the day and night. While 4-week-olds sleep a lot, it’s not for long stretches at a time. They wake often, usually due to hunger. While this is normal, it’s also frustrating for exhausted parents. In other words, it’s still way too early to expect babies this age to sleep through the night. You may see that start to happen around 3 months or later.

Four weeks is still a time when parents must be extra mindful of the danger of SIDS (Sudden Infant Death Syndrome). The American Academy of Pediatrics (AAP) advises that parents keep their babies in the same room but not allow them to sleep in the same bed. Always place your baby to sleep on their back on a firm mattress without any blankets, pillows, toys, or crib bumpers. 

When to Call the Pediatrician

At only 4 weeks old, it may be too early to tell if your infant is behind on certain milestones. After all, they’re still a newborn! That said, the American Academy of Pediatrics (AAP) recommends talking to your baby’s doctor if you observe any concerning signs of developmental delays. These may include the following:

• difficulty sucking or feeding
• not blinking or responding to bright light
• inability to follow nearby objects
• unresponsiveness to loud noises
• trembling lower jaw when not crying
• loose or “floppy” limbs
• lack of arm or leg movement

The Takeaway on 4-Week-Old Baby Development Milestones

By 4 weeks, many parents and caregivers start to feel like they're finding their groove with the whole baby care routine. Others still feel like they’re winging it from day to day. Both are perfectly normal! You and your newborn are still learning about one another. Try to accept any help that’s offered (especially if you’ve got a fussy baby), and don’t neglect your own self-care in the process. A healthy, well-fed, and well-rested parent can take better care of their baby. Always reach out to your pediatrician if you have any concerns about your newborn’s behavior, care needs, or overall health.