By four months old, most babies can hold their head steady, coo back at you, and smile on purpose to get your attention. These are the milestones that 75% or more of babies reach by this age, according to the CDC’s updated checklist. Every baby develops on their own timeline, but this is a useful picture of what to look for and what to encourage.
Movement and Physical Skills
Four months is when your baby starts feeling noticeably stronger. The most visible change is head control: when you hold your baby upright, they should be able to keep their head steady without wobbling or needing support from your hand. This is a big shift from just a few weeks earlier, when their head would bob around during position changes.
During tummy time, a four-month-old typically pushes up onto their elbows and forearms, lifting their chest off the floor to look around. This mini push-up builds the shoulder and back muscles they’ll eventually need for rolling and crawling. You might also notice your baby swinging their arms at toys hanging nearby, practicing the hand-eye coordination that will soon let them reach and grab with intention. If you place a toy in their hand, they can hold onto it, and they’re starting to bring their hands to their mouth regularly.
Rolling over hasn’t happened for most babies at this stage. Some early rollers manage tummy-to-back around now, but it’s more common between five and six months. If your baby isn’t rolling yet, that’s completely normal.
Social and Emotional Milestones
At four months, your baby’s smile changes in a meaningful way. Rather than just smiling in response to your face, they now smile on their own to get your attention. This is an intentional social behavior, and it’s one of the earliest signs that your baby understands cause and effect in relationships: “If I smile, someone interacts with me.”
You’ll also hear chuckling when you make silly faces or sounds, though a full belly laugh usually comes a little later. Your baby is actively working to keep your attention now, using a combination of eye contact, movement, and sounds. They’re no longer a passive observer. They’re a participant in the interaction, and they’ll fuss or vocalize when they want you to re-engage.
Language and Communication
Four-month-olds are in the “cooing” stage. You’ll hear vowel-heavy sounds like “oooo” and “aahh,” often in stretches that almost sound conversational. One of the key milestones is that your baby makes sounds back when you talk to them. This back-and-forth, even though it’s not words, is the foundation of conversation. They’re learning the rhythm of communication: you speak, I respond, you respond back.
Your baby should also turn their head toward the sound of your voice, showing they recognize it and are interested. This is an important sign that hearing is developing normally. Babies who consistently don’t turn toward voices or startling sounds deserve a closer look from their pediatrician.
Thinking and Learning
Cognitive milestones at this age are subtle but real. A hungry four-month-old will open their mouth when they see a breast or bottle approaching. This means they’re connecting a visual cue with what’s about to happen, which is basic anticipation and memory at work. You’ll also catch your baby staring at their own hands, turning them over, watching their fingers move. This is early body awareness: they’re figuring out that those hands belong to them and that they can control what they do.
Feeding and Sleep Patterns
Most four-month-olds eat every three to four hours, whether breastfed or formula-fed. Overnight feeds are still common, typically one or two per night. Feeding is generally well-established by now, meaning sessions are more efficient and predictable than they were during the newborn phase.
Daytime naps usually number two or three, totaling about three to four hours of daytime sleep. Many parents notice a shift around this age sometimes called the “four-month sleep regression,” where a baby who was sleeping longer stretches suddenly starts waking more often. This is linked to changes in sleep cycle maturity and is temporary, though it can be exhausting. Solid foods are not typically introduced at four months; most guidelines recommend waiting until around six months.
Activities That Support Development
You don’t need special equipment to help your baby practice these skills. Tummy time remains the single most important physical exercise. If your baby fusses during tummy time, try shorter sessions spread throughout the day rather than one long stretch, and get down on the floor at their eye level to make it more engaging.
For sensory development, offer toys with different textures so your baby can feel the difference between soft, bumpy, and smooth surfaces. Place a baby-safe mirror nearby during playtime, as babies this age are fascinated by faces, including their own. Narrate your day out loud: describe what you’re doing while you change a diaper, prepare a bottle, or walk through the house. This constant exposure to language patterns supports the cooing and back-and-forth communication your baby is practicing. Carrying your baby in a front carrier while you move around the house or take a walk gives them vestibular input (the sensation of movement through space), which helps with balance and body awareness over time.
Signs Worth Watching
Because the CDC’s milestones represent what 75% or more of babies can do by four months, missing one skill doesn’t automatically signal a problem. But certain patterns are worth raising with your pediatrician:
- No head control. If your baby’s head still flops when held upright, their neck and core strength may need assessment.
- No social smiling. A baby who never smiles on their own or doesn’t try to get your attention with eye contact, sounds, or movement may benefit from a developmental screening.
- No response to sound. Not turning toward your voice or reacting to loud noises could indicate a hearing concern.
- No cooing or vocalizing. Babies who are very quiet and don’t make vowel sounds or respond vocally when spoken to should be evaluated.
- No interest in hands or toys. A baby who doesn’t watch their hands, hold a toy placed in their grip, or bring objects to their mouth may be behind on fine motor or cognitive development.
Missing several milestones is more significant than missing one. Early intervention services are available in every U.S. state for babies under three, and the earlier a delay is identified, the more effective support tends to be. Your baby’s four-month well-child visit is a natural time to bring up any concerns.