First smiles, coos and recognising you
Early milestones are joyful signposts. Remember every baby is different, milestones are things most babies do by an age, not a deadline. This summarises CDC and NHS guidance.
What developmental milestones mean
Milestones describe what most babies can do by a given age. They are signposts, not deadlines. Babies who reach them at the later end of the typical range are not behind; babies who reach them early are not more advanced. Premature babies should be assessed from their corrected age (the due date, not birth date), so a baby born 6 weeks early should be assessed 6 weeks later than the calendar would suggest. The CDC revised its milestone checklist in 2022, moving several milestones to later ages to better reflect what most babies actually do; older checklists may show different ages.
Milestones also cover several areas at once. Motor development (what the body can do), communication (sounds and gestures), cognitive development (thinking and problem-solving), and social-emotional development (relating to others) all move forward in parallel, and they inform and reinforce one another. A baby who can hold their head steady during tummy time has a better vantage point for watching your face; a baby who watches your face is learning the cues that drive social smiling and early conversation. Understanding this helps you see the full picture rather than focusing on one milestone in isolation.
If you have been given a milestone chart from an older booklet or parenting app that still uses the pre-2022 CDC ages, some of the ages listed may look different from what you see here. The 2022 revision is the current standard. If you are uncertain whether a chart you are looking at is up to date, your health visitor or GP is the best person to ask.
Around 2 months: the first real smile
A social smile is one of the most memorable early milestones. It is a deliberate response to a familiar face or voice, distinct from the reflex "wind" smile that appears in sleep or at random. Around 2 months, most babies also begin to calm when spoken to or picked up, look at faces closely and track slow-moving objects with their eyes, react to loud sounds by startling, and begin making soft vowel sounds (ah, oh, eh).
The social smile tends to arrive somewhere between 6 and 8 weeks for most babies born at term. When it appears, it is usually unmistakable: your baby looks directly at you, their whole face seems to brighten, and they hold the expression for a moment before it fades. It is different from the fleeting, asymmetric smiles of the newborn weeks, which are reflexive and not directed at anyone in particular.
At this age, babies are also beginning to develop a preference for human faces over other visual stimuli, and for their primary caregivers' faces and voices above all others. This is the foundation of attachment, the secure emotional bond that research consistently links to wellbeing and resilience later in childhood. Every time you hold your baby close and make eye contact, you are actively building that bond.
How to support this stage: lots of face-to-face time during feeds and nappy changes; talking to your baby in a warm, animated voice; maintaining eye contact; smiling back when they smile. You do not need special activities or equipment. Ordinary caregiving moments, done attentively and warmly, provide everything your baby needs.
Around 4 months: laughing and taking turns
By 4 months, many babies laugh or chuckle, smile intentionally to get attention, and start to coo and babble in a way that sounds like they are taking turns in a conversation: they coo, then pause and look at you, as if waiting for a response. They begin to turn their head toward familiar voices and sounds, hold their head steadily during tummy time, and start to reach for objects. Consonant sounds like "ba", "da", and "ga" may appear.
This turn-taking in early vocalisations is significant. Language development researchers describe it as "proto-conversation", and studies have found that babies who experience more of these back-and-forth exchanges in early life tend to develop stronger language skills later on. You are not simply entertaining your baby when you respond to their coos; you are teaching them the fundamental structure of human communication.
At around 4 months, babies also become more aware of the social consequences of their behaviour. They begin to smile specifically at people rather than just responding to faces, which means they have learned that smiling gets a warm reaction from the people around them. They may also show early signs of distinguishing between familiar and unfamiliar faces, though stranger anxiety typically develops later, around 6 to 8 months.
How to encourage development at this stage: respond every time your baby coos or babbles, as this back-and-forth is how language develops; sing nursery rhymes with clear repetition; offer colourful objects within reach; continue regular tummy time sessions when awake and alert. Tummy time at this age also supports the motor milestones that follow in the second half of the first year, because the head control and upper-body strength it builds lay the groundwork for rolling and eventually sitting.
When to speak to your health visitor
Early support is far more effective than waiting. Speak to your health visitor if: your baby is not smiling socially by 3 months; there is no response to sounds or voices by 3 months; there is no eye contact or cooing by 3 to 4 months; or if a skill your baby had seems to have disappeared. The last point is especially important: the loss of a skill that was previously present is always worth reporting promptly, regardless of the specific milestone involved.
A health visitor appointment is not a test; it is a conversation to understand your baby's development and to arrange any support needed early. If a referral to a specialist is appropriate, getting it started sooner rather than later means your baby has access to support at the age when it is most effective. Many developmental concerns that are identified and supported in the first year have very good outcomes precisely because of that early action.
Trust your instincts as a parent. If something feels different about how your baby is responding to you or the world around them, it is always worth raising with a professional. You know your baby better than anyone, and that knowledge is genuinely useful clinical information. Professionals who work with babies take parental observations seriously. You will not be wasting anyone's time by asking.
Frequently asked questions
When should my baby give their first real smile?
Most babies smile socially, in response to a face or voice, by 6 to 8 weeks. If your baby has not smiled by 3 months, mention it to your health visitor at their next check. It does not necessarily indicate a problem, but it is worth having assessed.
What if my baby is not cooing by 3 months?
Cooing and soft vowel sounds typically begin around 2 months. If your baby is not making any vocal sounds by 3 months, or is not responding to your voice, speak to your health visitor. They can assess hearing and development and arrange a referral if needed.
What does normal babbling sound like at 4 months?
At 4 months, babbling often sounds like repeated vowel sounds (ah, oh) and early consonant-vowel combinations like "ba" and "ga". Your baby may coo, then pause as if waiting for your response, then coo again; this back-and-forth is the beginning of conversation. Laughing and chuckling also typically appear around this time.
What is tummy time and why does it matter?
Tummy time means placing your baby on their front while they are awake and supervised. It builds the neck, shoulder, and arm strength needed for rolling, sitting, and crawling. Start with short sessions from birth, on your chest or lap if the floor feels too far, and build up to several short sessions a day as your baby gets stronger.
Capture the firsts
Log milestones in Cubby with a photo, the first smile, the first laugh, and keep them all in one place.
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