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Your 4-Month-Old: Milestones & Development

February 26, 2024

Vera Malushi, PT, DPT, lends us her expertise as a pediatric physical therapist to recommend developmentally-appropriate ways to play with your 3-month-old. She is the founder of Milestones Pediatric Physical Therapy and shares a wealth of knowledge and tips on her Instagram page @milestones_pediatric_pt.

At 4 months old, your baby is beginning to show you their emerging personality, and it is enchanting! The bond between you two is stronger than ever, and it’s impossible not to be completely in love with your little one. Not only are they becoming deeply curious about the world around them, they're now ready for lots of social interaction, and love to smile, giggle, and coo at you and other caregivers. Big changes are happening, and this new chapter of life couldn’t feel more exciting! Here’s everything you can look forward to this month:

Physical development & movement

Gone are the days of tummy time struggles! Your baby is getting stronger by the day, and can now push up on their arms when placed on their belly. They’re also likely rolling in at least one direction, and may even learn to roll both ways in this next month. Hello, newfound mobility! If you haven’t already, now is the time to finish baby proofing your house, so that little hands don’t go where they shouldn’t.

Not only is your little one much more aware of their environment, their hand-eye coordination is quickly improving, and they may now be reaching for objects—like their feet! Babies discover their feet around this age, and yours will soon be grasping their tiny toes and bringing them to their mouth to explore.


Your little one is starting to string vowels and consonants together, so you may hear a lot of “ba-ba-ba-ba” and other babbling sounds. Repeat these simple sounds back to them and engage in the cutest, most nonsensical “conversation.” Your baby can copy simple sounds and expressions at this age, so make sure to smile and talk to them as much as you can throughout the day. Before you know it, your “conversations” will turn into an actual exchange of words!


Now that your baby can hold their head steady and their vision is rapidly developing, they’re even better at tracking objects. Your 4-month-old can also differentiate shades of color, especially red and green, and this opens up a new world of interest for them. Stimulate your baby’s vision by reading books with large, brightly colored images, as well as taking them on walks outside for a sensory-rich experience.


Although experts recommend holding off on solid food until babies are 5 or 6 months old, your baby’s pediatrician may have already given you the green light to begin introducing solids. It’s up to you if you want to go ahead and give your little one a first taste, but keep in mind that they don’t need more than a tablespoon of solid food once a day at this age. Baby’s diet should still consist mainly of breastmilk or formula, and any solids will be just for practice, not nutrition.


If your baby’s sleep has suddenly taken a sharp turn for the worse, you’re not alone. Around 4 months of age, babies undergo a biological change in their sleep pattern where they move from newborn phases of sleep into more adult-like sleep cycles. The result? More night wakings, more fussing, and more sleep struggles that make up the notoriously difficult 4-month sleep regression. While this can be a rough phase for you and your baby, it will pass. Your baby is growing and learning rapidly, and though it doesn’t feel like it at the moment, these trying times are fleeting. 

How to play with your 4-month-old

“In month 4, baby is much more observant and should have good neck strength. You have been practicing daily episodes of tummy time, and as of this month, baby should be able to enjoy playing on their belly for short bursts of time. This is a great time to provide sensory play during tummy time. Bring out the inflatable water mat and place it under baby’s belly. Or try a homemade Montessori-type project, such as adding some water to a shallow baking tray and letting baby splash around on their belly. By month 4, pediatric physical therapists recommend about 45 minutes of tummy time a day, broken up into smaller chunks!”
Dr. Vera Malushi, PT, DPT

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Your 4-Month-Old: Milestones & Development

About the Author: Alice

Alice Mendoza is a copywriter and blog writer based in Los Angeles. She began writing for a baby brand while on maternity leave, and realized she had found her niche. Today, she writes exclusively within the baby space, using her BFA in Creative Writing and her own experience as a mother to guide her. When she’s not working, you can find her chasing down her toddler, going on walks around the neighborhood, or watching reality TV.

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