Infant Development Guide (3–6 Months): Strength, Smiles & First Rolls
Baby Development 3–6 Months: From Reflexes to Intentional Play
Between 3 and 6 months, your baby begins to step out of the newborn phase and into a season of curiosity, movement, and connection. This is the stage where those tiny reflexes transform into intentional actions — reaching for toys, rolling with excitement, and sharing the sweetest belly laughs that light up your days.
At Movevery, we remind parents that infant development milestones during this stage are not about racing to “keep up.” They are about giving your child the space, safety, connection and opportunity to explore. These early months are the bridge between stability and mobility: your baby is learning how to control their head, discover their hands and feet, and practice the skills that will lead to sitting, crawling, and beyond.
Be Proud Of…
Each roll attempt, even the “almost” ones.
The joy your baby shows when they smile, coo, and giggle with you.
Your patience and creativity with tummy time, side play, and back play on the floor.
Look Forward To…
Rolling in both directions with growing confidence – your baby will gain strength and coordination in their core and shoulders.
Sitting with support – exploring the world from a new angle and practicing balance.
Curiosity and experimentation – your baby will begin noticing cause and effect, exploring how their actions affect the world.
Should I be tracking every milestone?
It’s natural to want to know how your baby is doing, but milestones aren’t meant to be a rigid checklist. Babies develop on their own unique trajectory, and there’s a wide range of normal for when skills emerge.
It’s helpful to have a sense of the kinds of skills your baby may be working on at each age, but think of milestones as fluid guideposts, not boxes to check off. If something feels off to you—whether it’s movement, comfort, or interaction—it’s always worth reaching out for support.
At Movevery, we remind parents that milestones are guides. The goal is to nurture development while giving yourself permission to enjoy the journey.
Let's focus on weeks 12–16 Weeks (3–4 Months): Discovering Purposeful Movement
Between 12 and 16 weeks, babies are learning to move with intention, building strength, balance, and coordination.
Little Movements to Look For Around 3-4 Months:
Brief supported sitting – some babies may sit briefly with support while gaining a new vertical perspective.
Core and back strength – balance develops from the center outward, supporting early rolling and eventually independent sitting.
Increased awareness of surroundings – noticing objects, faces, and spaces from a new angle.
Intentional exploration – combining movements and grasping to interact purposefully with toys and caregivers.
Parent Tip: Your baby loves seeing the world from new angles! Try holding them upright on your lap or placing toys at eye level during supported sitting. This helps strengthen their core and encourages curiosity and engagement.
Parent Question: What/Do toys help my babies development?
When it comes to toys, I always like to encourage a “less is more” approach. There’s so much consumerism around baby gear, and it’s easy to feel like you need all the things. In reality, your baby benefits most from space to move, explore, and play.
A few simple toys go a long way: a floor mirror with spinners, an O-ball, bubbles, teethers, a soft crinkly book, physioball, and a padded play mat are all wonderful options. Subscription kits like Lovevery can also be a nice way to rotate age-appropriate toys without overloading your space.
I’ve put together a list of my favorite things if you’d like more ideas for purposeful play. Coming Soon!
Let's focus on weeks 16–20 (4–5 Months): Rolling & Reaching
Between 16 and 20 weeks, babies are exploring side-to-side movement, strengthening their core, and preparing for intentional play and mobility.
Little Movements to Look For Around 4-5 Months:
Side-to-side rolls – shifting weight on forearms and tipping onto their side, laying the groundwork for full rolling.
Hands-to-feet play – building core strength, pelvic mobility, and awareness of their body in space.
Leg lifting and kicking – strengthens the core and provides momentum for rolling and early sitting.
Bringing toys to mouth – supporting midline awareness, hand-eye coordination, and early self-feeding skills.
Intentional reaching and grasping – combining upper-body control with coordination to interact with objects.
Upper body and head-trunk dissociation – practicing control that prepares for rolling, pivoting, and sitting.
Parent Question: When should rolling happen?
Rolling is one of the first big mobility milestones, and it usually begins between 3–5 months. Many babies first learn to roll from tummy to back, then progress to rolling from back to tummy as their strength, coordination, and confidence grow. One of the best ways to support this milestone early is by rolling your baby into and out of tummy time, rather than just placing them on their belly.
This not only makes the transition smoother, but also helps teach their muscles, provide sensory input, and build the motor planning skills they need to eventually roll on their own. Keep in mind, there’s a wide range of normal—rolling develops through repeated practice in different positions, like tummy time, side play, and back play.
At Movevery, we focus on helping babies build the strength, sensory input, and body awareness needed so rolling emerges naturally as part of play.
Let's focus on weeks 20–24 (5–6 Months): Building Core & Social Growth
Between 20 and 24 weeks, babies are strengthening their balance, exploring movement, and engaging more socially.
Little Movements to Look For Around 5–6 Months:
Pivoting in tummy time – turning in a semi-circle to reach toys and activating obliques for diagonal movement patterns.
Propping on hands while sitting – using arms for balance and gaining strength for more upright play.
Shifting weight in tummy time – reaching for toys while on the tummy, building balance and trunk control.
Exploring visually in all directions – looking up, down, and side to side to strengthen neck and trunk muscles as vision and head control work together beautifully.
Playing with hands at midline and across the body – stacking cups, banging toys, and reaching purposefully to build coordination.
Engaging socially – sharing more laughter, smiles, and interaction with caregivers during play.
Reaching and playing intentionally – moving hands with smoother control, grabbing, mouthing, and transferring toys between hands to strengthen fine motor skills.
Parent Question: When should my baby sit?
Sitting is a milestone that develops gradually. Around 4–6 months, many babies start sitting with slight support—like leaning on their own arms (often called “tripod sitting” or “prop sitting”). By 6–8 months, babies typically gain the strength and balance for independent sitting without support.
As their stability improves, sitting becomes more dynamic—reaching for toys, turning to look around, and using their arms freely. Eventually, babies learn to move into and out of sitting on their own, which is an important step toward crawling and exploring their environment.
At Movevery, we focus on helping babies build the core strength, balance, and coordination needed for sitting—always through playful, purposeful movement.
Parent Question: How do motor and sensory skills connect?
Motor and sensory skills are deeply connected—movement and sensory play work together to wire the brain for learning. Every small experience your baby has, from lifting their head to pushing against the floor, strengthens those brain-body pathways. The vestibular system, which is activated by head movement, helps your baby develop balance, coordination, and spatial awareness.
The proprioceptive system, stimulated through pressure, pushing, pulling, and weight-bearing, builds body awareness and teaches your baby where their body is in space. Together, these systems support safety, coordination, and confidence as your baby grows.
At Movevery, we remind parents that tummy time, side play, and back play aren’t just about strength—they’re powerful ways to give the brain the sensory input it needs to thrive.
Dr. Nicole’s Top Tip: “Celebrate progress, not perfection. Play is the work of babies — and it’s enough.”
Curious Baby Sloane lying sideways, watching herself in the mirror.
Top 5 Common Baby Development Concerns: 5 Things Parents Worry About
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Not necessarily. Rolling is a complex skill that combines visual attention, strength, coordination, and motor planning. While some babies begin rolling around 4 months, many don’t master it until closer to 6 months—both are within the range of typical development.
What matters most is whether your baby is showing the “mini-stones” or stepping stones toward rolling.Are they kicking their feet equally?
Do they try to roll onto their side?
Are they turning their head to follow a toy or shifting their weight in play?
These small movements are signs your baby is building the foundation they need.
At Movevery, we encourage parents to focus on the progress toward rolling rather than the exact age it happens. If your baby isn’t there yet but is exploring movement and showing those mini-steps, they’re on the right path. If something feels off—like limited movement to one side or little interest in shifting—you can always reach out for extra support. -
At this stage, it’s really about variety and progression. If your baby is starting to get onto their tummy on their own, that’s wonderful! If not, the focus shifts to practicing the skills that will help them get there. Instead of only placing your baby on their tummy, try rolling them into and out of tummy time.
This not only builds the muscles they need, but also provides important sensory input and helps with motor planning, teaching their body how to eventually make the transition independently.
Keep tummy time fun and engaging: get down on their level, offer toys like teethers, an O-ball, or bubbles, and invite siblings to join in the play. The more playful and interactive it feels, the more your baby will enjoy spending time in this position.
At Movevery, we remind parents that tummy time isn’t about hitting a perfect number—it’s about weaving in variety, consistency, and connection throughout the day. -
If your baby seems “floppy,” it’s always important to consult a medical provider to rule out any underlying concerns. Sometimes this presentation is related to hypotonia, which means your baby has abnormally low muscle tone. Low tone doesn’t mean your baby can’t get stronger—it simply means they may need to work a little harder to hold postures like head control.
This is where early therapy can make a big difference. A skilled pediatric therapist can support babies with hypotonia by focusing on early head control, core activation, and strengthening through purposeful play and positioning.The goal is not only to build endurance, but also to provide the sensory input and motor practice your baby needs to reach milestones in their own time.
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If your baby consistently reaches with only one hand, it may be a sign that their body feels more comfortable using one side over the other. Sometimes this is related to tension patterns, asymmetry, or torticollis, which can limit how easily they turn or shift their weight. Reaching equally with both hands is important for vision development, reflex integration, milestone progression, and preventing imbalances as your baby grows. Handedness typically doesn’t develop until between 2 and 4 years of age.
If you notice this pattern, it’s a good idea to reach out for support. A skilled therapist can assess what might be limiting movement and provide gentle strategies, positioning, and play activities to encourage your baby to use both sides of their body. -
No—sitting develops gradually and looks different for every baby. Around 4–6 months, many babies begin sitting with slight support or propping forward on their arms (“tripod sitting”). By 6–8 months, they often progress to sitting independently without support, and eventually learn to move into and out of sitting while reaching for toys.
There’s a range of normal when it comes to sitting. What’s most important is that your baby is showing progression toward stability—building strength in the neck, shoulders, back, and core, and practicing balance through play. If you’re concerned your baby isn’t moving toward sitting, early support from a pediatric therapist can help guide the way.
Disclaimer:
This guide provides a general overview of early child development. Every baby grows at their own pace, and milestones can happen earlier or later than the ages listed—both are completely normal. This is not medical advice. If you have concerns, use these ranges as a guide for when to check in with your pediatrician or a pediatric physical therapist for personalized support.
