Your 5-week-old baby: weight, tummy time, vision, smiles and early coos
Five weeks. It sounds tiny, but your baby has already changed so much since those hazy first days at home. At 5 weeks old your newborn is edging out of that brand‑new phase and showing more of who they are. You might notice longer awake times, more deliberate movements, and, if you are lucky, that first real smile that makes your heart do a little flip.
This is a lovely stage to simply watch. To observe. To soak in all the small baby milestones that quietly add up to big baby development.
Let’s walk through what is typically happening with a 5 week old baby, from head to toe and from body to brain, and what you might notice this week at home.
Physical development at 5 weeks: growing, wriggling, lifting
Steady weight gain and growth
By 5 weeks old, most babies are settling into their own growth curve. If you have had a recent check with your GP, health visitor or paediatrician in the UK or Ireland, you have probably seen those curved centile lines in the “red book” or child health record.
A common pattern around this stage:
- Many babies gain roughly 150 to 200 g per week (around 5 to 7 oz).
- Length and head circumference are slowly increasing too, not just weight.
- Clothes that were baggy a couple of weeks ago are starting to fit properly.
The exact 5 week baby weight will vary a lot. Some 5 week old babies are petite, others are chunky with delicious thigh rolls. What matters more than the number on the scale is the pattern:
- Weight is generally going up, not down.
- Your baby has several wet nappies a day and regular poos.
- They seem reasonably content between feeds, at least some of the time.
If anything about growth or feeding is worrying you, trust that feeling and speak to your health visitor, GP, or a local breastfeeding / infant feeding clinic. There is a wide range of normal, but you should never feel brushed off.
Tummy time at 5 weeks: when do babies lift head?
This is usually the age when parents start to ask, “So... when do babies lift their head properly?”
At 5 weeks, tummy time is still hard work. The head is heavy, neck muscles are still strengthening, and a few minutes can feel like a full gym session for your baby.
You might see:
- Brief periods where your baby can lift their head to about 45 degrees off the surface.
- Little “push-ups” where they bob their head up and then gently drop down again.
- Knees tucked up and arms pulled in, with some weight bearing through the forearms.
If tummy time is a struggle, you are not alone. Some babies protest loudly.
Try:
- Very short bursts, 30 seconds to 2 minutes, a few times a day.
- Tummy time on your chest while you are half reclined - that still counts.
- Rolling a small towel under their chest to make it a bit easier.
- Getting at eye level and chatting or singing. Your face is their favourite view.
These early efforts are part of the 5 weeks old baby development that helps them later roll, sit and crawl. It might not look like much now, but every tiny head lift is working those muscles.
Arms, legs and early coordination
Around 5 weeks, you might notice your baby’s movements look ever so slightly less random. Still jerky, yes, but less flaily.
Common changes:
- Arms and legs may move in more rhythmic patterns, not just sudden startles.
- When you place a rattle or soft toy in their hand, they might briefly hold it, even if by reflex.
- Kicks might seem more purposeful, especially when they are excited on the changing mat.
This does not mean they can control their movements properly yet. Far from it. But it is a sign their nervous system is maturing and that baby milestones in physical control are ticking along in the background.
Vision: your 5 week old is really looking at you
Baby vision at 5 weeks
Newborn vision starts off pretty blurry and close-range. By 5 weeks:
- Many babies can focus quite well on faces or objects about 20 to 30 cm away.
- Your baby may look more intently at a face or high-contrast pattern.
- You might notice longer periods where their eyes seem steady, not just darting around.
You are likely the number one thing they want to look at. Toys are nice, but your face still wins.
Baby tracks objects at 5 weeks
This is often the week parents notice their baby tracks objects much more smoothly.
You might see:
- Your baby following a face or toy as it moves from side to side in a wider arc.
- Less “jumping” eye movement and more fluid tracking.
- A mix of head and eye movement as they follow something interesting.
Try a simple at-home check:
- Hold your face or a simple toy about 20 to 30 cm from their face.
- Slowly move it from the centre towards one side, then across to the other.
- Watch if their eyes and maybe their head follow it.
If they occasionally lose it and then refocus, that is completely normal at this age.
Preference for faces
One of the loveliest parts of baby development at 5 weeks is how obviously they seem to prefer faces.
Signs your baby likes looking at faces:
- They stare at you quietly when you chat to them.
- They seem calmer when someone leans in close and talks gently.
- They may look intently at photos or simple, face-like patterns.
There is a strong social reason behind this. From very early on, babies are wired to tune into humans. That preference for faces links straight into social development at 5 weeks and the early building blocks of communication.
Hearing and response to sound: your voice is their anchor
Baby hears and responds at 5 weeks
By now, your baby’s hearing is well developed, and their responses become more obvious.
You might notice:
- Your baby responds to voice, especially familiar ones, by quietening, moving, or widening their eyes.
- They can startle at sudden sounds like a dropped pan or a dog bark.
- Soft background noise, like a fan or gentle music, may settle them.
Babies at this stage are not just hearing, they are starting to sort sounds - what is familiar, what is new, what feels safe.
Turning towards familiar sounds
Around 5 weeks, some babies start to show a small but clear milestone: they may turn their head towards familiar sounds, particularly your voice.
Look for:
- A slight head turn if you speak from one side.
- Movements that seem to say “Where is that coming from?” when they hear you.
- A calmer expression when they recognise a sound associated with comfort, for example the kettle if that often leads to a cuddle and a sit-down.
If your baby does not always turn or only does it sometimes, do not panic. These early newborn milestones can come and go, especially if they are tired or hungry. Consistency will build gradually over the next few weeks.
If you ever have concerns about hearing - for example if your baby never startles at loud sounds or seems not to respond to voices at all - speak with your GP or health visitor. Early reassurance or support can be very helpful.
Social development at 5 weeks: the magic of the first real smile
Reflex smiles vs real social smiles
This is the bit many parents secretly wait for. That first proper grin.
You may have seen little half-smiles in sleep in the earlier weeks. These are usually reflex smiles - automatic, fleeting, not really connected to anything happening around them.
A real social smile is different.
At 5 weeks, many babies give that first genuine smile:
- It happens in response to something - a face, a familiar voice, gentle tickling.
- The smile lights up the whole face, not just the mouth.
- The eyes join in. They may slightly crinkle, and the expression looks bright and engaged.
You smile. They smile back. For a moment it can feel like the whole world shrinks to just the two of you.
Some babies hit this social development milestone slightly earlier, some a week or two later. Both are normal. The rough window for the first social smile is often between 4 and 8 weeks.
Encouraging social smiles (without pressure)
You cannot force a smile, and you genuinely do not need to. But you can create lovely moments that make it more likely:
- Get close, about 20 cm from their face, where they can see you best.
- Use a slightly sing-song voice, often called “parentese”.
- Pause after you speak, as if you are waiting for their reply.
- Smile warmly and give them time to respond.
Sometimes they will stare, sometimes they will frown, and sometimes, suddenly, there it is - the smile that brightens the whole day.
If your baby is not smiling socially yet at 5 weeks, do not jump to worry. Keep chatting, cuddling and offering those face-to-face moments. Many perfectly healthy babies take a little longer.
Communication at 5 weeks: early coos and conversations
First cooing sounds
You may begin to hear new sounds this week. Not cries. Not grunts. Something softer.
Many babies around 5 weeks start to make cooing vowel sounds, especially when calm and content. You might hear:
- Soft “ah” sounds.
- Gentle “oh” noises.
- A little string of coos while they lie on their back content after a feed.
These are early steps in communication. Your baby is experimenting with their voice, testing what they can do with their mouth and breath.
Turn-taking “chats”
If you respond to those coos, something lovely often happens.
Try this:
- When your baby makes a sound, pause and look at them.
- Echo back a similar sound or answer with a short phrase, like “Oh, really?”
- Wait again.
You might notice your baby:
- Looks at you as you “answer”.
- Has a go at making another sound after you stop.
- Kicks or waves arms while they coo.
That simple back-and-forth is the start of conversation skills. No words yet, but the structure of communication is already under construction.
This early chat time links with core baby milestones related to language in the first year. It may feel small, but cooing and responding are like laying the first bricks for understanding and eventually speaking words.
Behaviour and personality: longer alert times and tiny humans in the making
Alert periods of 20 to 30 minutes
In the first couple of weeks, your baby’s awake times might have been very short, sometimes just a few minutes between feeds.
By 5 weeks:
- Many babies can manage alert periods of 20 to 30 minutes.
- These windows are ideal for gentle interaction - cuddles, chats, short tummy time.
- After that, they may quickly tip from “happy and awake” to “overtired and cross”.
You might start to recognise a pattern:
- Wake and feed.
- A short period of calm, bright alertness.
- Sleep again, sometimes with a bit of grumbling on the way down.
Not every day will be neat. Growth spurts, windy tummies, or the classic “witching hour” in the late afternoon can throw things around. But overall, these more predictable alert periods are one sign of maturing 5 week milestones in behaviour.
Emerging personality traits
It can feel too early to talk about personality, but many parents notice little traits peeking through at 5 weeks.
You might see your baby is:
- Naturally more laid-back or more intense.
- Very vocal when uncomfortable, or more quietly alert.
- Very interested in looking around, or more focused on cuddles and closeness.
None of this is fixed forever. Babies change a lot. Still, recognising who your baby seems to be right now can help you respond to them in a way that feels right for both of you.
Instead of thinking “Shouldn’t they be doing X by now?” it can be kinder to think, “This is how my baby does things at 5 weeks” and work with that.
Every baby is different: the wide range of normal
When you read about baby development and newborn milestones, it is very easy to turn every sentence into a checklist. It is also very easy to feel you are behind if your baby does not tick every box at exactly 5 weeks.
Real life is not that tidy.
Some perfectly healthy babies at 5 weeks old:
- Have already given several social smiles. Others are still practising.
- Can lift their head to 45 degrees in tummy time. Others barely manage a little bob.
- Track objects smoothly across a room. Others only follow a short distance.
- Coo every day. Others are mainly expressing themselves with cries and grunts.
Development is more like a range than a straight line. Babies have growth spurts in behaviour just as they do in weight.
A few simple guidelines can help:
- Look at the overall trend: Is your baby more alert and interactive than they were at 2 weeks?
- Think about feeding and comfort: Are they generally gaining weight, feeding reasonably, having wet nappies and periods of calm?
- Trust your instincts: If something feels very off, or you are worrying every day, speak to a professional. You never need to apologise for asking.
How to enjoy this 5 week window
These early weeks can be intense. Sleep is unpredictable, your body is still recovering, and advice comes at you from every direction. You are probably tired of hearing the phrase “sleep when the baby sleeps”.
Even so, 5 weeks can also be quietly joyful.
A few gentle ideas:
- Use those 20 to 30 minute alert windows for low-pressure connection: a soft song, a simple game of “I’m going to kiss your toes”, a bit of tummy time at 5 weeks on your chest.
- Notice the details: the way their fingers curl around yours, the tiny pause before a smile, the serious look they give the ceiling light.
- Take photos or short videos, not just of big smiles but of ordinary moments: a coo after a feed, a determined head lift, that very specific “I’m about to cry” face.
Your 5 week old baby will be different again in just a fortnight. More awake, more expressive, more themselves.
For now, this week, you have a small human who is beginning to:
- Grow steadily and get stronger each day.
- Lift their head a little higher.
- Focus and track your face.
- Turn towards familiar sounds and respond to your voice.
- Offer that first real social smile.
- Experiment with cooing sounds and early “conversations”.
- Show flashes of personality and longer, brighter awake times.
All part of the extraordinary, everyday story of 5 weeks old baby development.
And you? You are learning them. They are learning you. That might just be the most meaningful milestone of all.
We as the developers of the Erby app disclaim any liability for any decisions you make based on this information, which is provided for general informational purposes only and is not a substitute for personal medical advice.
