3 to 6 Months: Your Baby's Development Month by Month

Many parents describe the 3–6 month window as the sweet spot of babyhood: the exhaustion of the newborn period is easing, sleep is (usually) improving, and your baby is becoming genuinely interactive and fun. Here's what to look out for.

3 months

Motor:

• Good head control — can hold head steady when supported sitting or when held upright
• On tummy, can lift head and upper chest, propping on forearms
• Hands are starting to open — spending less time in fists
• Beginning to bat at hanging toys

Communication and social:

• Social smiling is well established
• Cooing and making vowel sounds — starting to "talk back" to you
• Turns head towards voices and familiar sounds
• Recognises your face and voice clearly

Cognitive:

• Follows moving objects smoothly with eyes
• Starting to show preference for familiar people over strangers
• Interested in their own hands

Sleep (typical at 3 months):

• May be doing 1–2 longer stretches at night (3–5 hours is common)
• Usually 3–4 naps per day
• Still variable and wide individual differences — all normal

4 months

Motor:

• First attempts at rolling — usually back to side first
• Reaching for objects with some accuracy
• Sits with support, head steady
• May start to bear weight on legs briefly when held standing (this is fine — it doesn't cause bow legs)

Communication and social:

• First proper laughs — social, physical, and in response to your games
• Babbling beginning — "ooh", "ah", and early consonant sounds
• Reacts to your emotional tone — smiles when you smile, responds to playfulness

Cognitive:

• Recognises familiar objects
• Interested in cause and effect — shaking a rattle to hear the sound
• Beginning to understand routines

The 4-month sleep regression: A well-known developmental disruption caused by sleep cycle maturation — previously deep-sleeping babies start waking between cycles like adults do. Hang in there.

5 months

Motor:

• Many babies roll both ways by now (though back-to-tummy is harder and comes later)
• Sits briefly without support — wobbles back
• Reaches with accuracy, transferring objects hand to hand
• Mouths everything — hands, toys, your fingers

Communication and social:

• Responds to their name (beginning)
• Makes a wider range of sounds, experimenting with volume and pitch
• Blows raspberries — a huge developmental achievement, not just a party trick
• Recognises primary caregivers clearly; may show early stranger wariness

Cognitive:

• Interested in their own reflection in a mirror (they don't know it's them yet)
• Beginning to notice when objects disappear — proto-object permanence

6 months

Motor:

• Sitting steadily without support in many babies
• Rolling confidently in both directions
• Beginning to bear weight on hands in a push-up position on tummy
• Raking grasp — using fingers to rake objects towards them

Communication and social:

• Babbling with consonants: "ba", "da", "ma" (not yet with meaning)
• Imitating facial expressions and sounds
• Clearly prefers familiar people; stranger awareness more pronounced

Cognitive:

• Object permanence beginning to emerge — looks for dropped object
• Cause-and-effect understanding improving rapidly
• Starts to understand "no" as a tone, though not yet the word

Physical:

• Teething often beginning — first teeth usually around 6 months (though anywhere from 4–14 months is normal)
• Ready to start solids — the NHS recommends beginning around 6 months

What to do with your 3–6 month old

Play that supports development:

• Tummy time daily — still important at this age for motor development
• High-contrast books and pictures — their colour vision is now much better
• Musical instruments — simple shakers, bells
• Peekaboo and hide-and-seek with toys — great for cognitive development
• Singing and narrating — talk to your baby constantly about what you're doing
• Sensory play — different textures, temperatures (safe), sounds

Avoid:

• Screen time — the NHS recommends avoiding screens (other than video calls) under 2 years
• Jumperoos or bouncers for extended periods before baby can sit unaided — fine for short periods, but shouldn't be a substitute for floor time

When to seek advice

Speak to your health visitor or GP if at 6 months your baby:

• Isn't smiling or showing social responsiveness
• Doesn't turn towards sounds
• Shows no interest in people or objects
• Can't hold their head steady when supported sitting
• Isn't attempting to reach for objects

These checks happen at the NHS developmental review at 9–12 months, but you don't need to wait — flag any concerns as soon as you notice them.