Four Month Old Milestones: What to Expect

Your baby at four months is becoming a true interactive partner. They're laughing, reaching for toys, rolling over, and showing a delightful personality. This is one of the most rewarding stages of babyhood—your infant is engaged, responsive, and changing rapidly.

The fourth month often brings a burst of new skills as babies gain better control over their bodies and become more interested in the world around them. Here's what to expect. AAP

Major Developments at Four Months

The social explosion: CDC

• Laughs out loud
• Smiles spontaneously
• Enjoys playing with people
• May cry when playing stops
• Copies facial expressions and sounds

Physical breakthroughs:

• Much stronger head and neck control
• May roll over (tummy to back usually first)
• Reaches for and grabs toys
• Brings objects to mouth
• Bears weight on legs when held upright

Physical Development

Head and neck: Mayo

• Holds head steady without support
• Lifts head and chest high during tummy time
• May look around while on tummy
• Good control when sitting supported

Rolling:

• Many babies roll tummy to back first
• Some roll back to tummy
• May surprise themselves when it happens!
• Once rolling starts, they'll practice constantly

Hands and reaching:

• Deliberately reaches for objects
• Grasps toys (palmar grasp)
• Brings everything to mouth
• Holds and shakes rattles
• Hands are usually open, not fisted
• Pushes up on extended arms during tummy time

Legs:

• Kicks strongly
• May bear weight on legs when held
• Pushes against floor
• Straightens legs when lying down

Cognitive Development

Learning and exploration: AAP

• Curious about everything
• Studies objects carefully
• Shakes, mouths, and bangs toys
• Beginning to understand cause and effect
• Watches faces intently

Memory and anticipation:

• Recognizes familiar faces and objects
• Anticipates feeding, play routines
• May get excited seeing bottle/breast
• Remembers recent events

Problem-solving:

• Works to get toys just out of reach
• Experiments with objects
• Notices how things work
• Interested in mirrors

Communication Development

Vocalizations: CDC

• Babbles with consonants (ba, ma, da)
• Laughs and squeals
• Makes sounds to get attention
• Imitates sounds
• Different sounds for different emotions

Listening and responding:

• Turns toward sounds and voices
• Responds to own name (beginning)
• Shows interest in music
• Understands tone of voice

Social communication:

• Initiates interaction
• Makes eye contact to communicate
• Uses sounds and movements expressively
• Enjoys "conversations" (back and forth sounds)

Social and Emotional Development

Attachment: AAP

• Strong preference for familiar people
• May show wariness around strangers (beginning)
• Clearly distinguishes caregivers
• Seeks interaction and attention

Play:

• Enjoys simple games (peek-a-boo)
• Laughs during play
• Interested in mirrors
• May enjoy watching other children

Self-awareness:

• Discovering own hands and feet
• May find feet fascinating
• Beginning to understand self as separate being
• Shows preferences

Sleep at Four Months

Patterns: NSF

• 12-16 hours total daily
• May sleep longer stretches at night (4-6 hours or more)
• Usually 3-4 naps during day
• Beginning to consolidate sleep

The 4-month sleep regression:

• Many babies experience disrupted sleep around this age
• Brain development causes sleep pattern changes
• May take time to settle into new patterns
• This is temporary

Feeding at Four Months

Milk feeds: AAP

• Still exclusively breast milk or formula
• About 24-32 ounces formula daily
• Breastfed: 5-7 feeds daily
• More efficient feeding sessions

Solids:

• AAP recommends waiting until about 6 months
• Some signs of readiness appearing
• Consult pediatrician about timing
• Don't rush—breast milk/formula is sufficient

The 4-Month Checkup

At the 4-month well-visit: AAP

Physical exam:

• Growth measurements
• Development assessment
• Physical examination

Vaccinations:

• Second doses of DTaP, IPV, Hib, PCV
• Rotavirus (second dose)

Topics to discuss:

• Sleep patterns/regression
• Development
• Beginning solid foods preparation

Milestones Checklist

Most 4-month-olds: CDC

• Smile spontaneously
• Babble with expression
• Like to play with people
• Copy movements and facial expressions
• Hold head steady without support
• Push down on legs when feet on hard surface
• Bring hands to mouth
• Hold and shake toys
• Swing at dangling toys

Some 4-month-olds may:

• Roll over (tummy to back)
• Laugh out loud
• Begin to sit with support
• Push up on extended arms

Talk to your doctor if:

• Doesn't watch things as they move
• Doesn't smile at people
• Can't hold head steady
• Doesn't coo or make sounds
• Doesn't bring things to mouth
• Doesn't push down with legs when feet on hard surface

Supporting Development

Physical: Mayo

• Tummy time (60-90 min daily in sessions)
• Floor play for movement
• Provide safe toys to reach for
• Practice supported sitting

Cognitive:

• Simple cause-and-effect toys
• Different textures and sounds
• Reading and singing
• Mirror play

Communication:

• Talk throughout the day
• Respond to their sounds
• Read picture books
• Sing songs with actions

Social:

• Face-to-face play
• Peek-a-boo and simple games
• Let them interact with safe others
• Follow their lead in play

What's Coming Next

In the next months:

• Rolling in both directions
• Sitting without support
• First foods introduction
• More babbling and sounds
• Possible first tooth
• Increased stranger awareness

The Bottom Line

Four months is a delightful age—your baby is truly interactive, responsive, and showing a real personality. Major developments include laughing, rolling, deliberate reaching, and beginning babbling. Enjoy this engaging stage!

Key milestones:

• Laughs out loud
• Rolls over (or beginning to)
• Reaches for and grabs toys
• Holds head steady
• Babbles with consonants
• Enjoys social play

Clara is here to celebrate your four-month-old's development!