- Home
- Tools And Resources
- Baby Development Calendar
- 15 - 16 Weeks Old Baby Development Milestones
Your baby at 15 – 16 weeks: development milestones & what to expect
At 15–16 weeks, your baby is getting stronger and more active. Learn key milestones, from sitting support to play and muscle development.
7 min
It’s incredible to look at your little one now and see how much they’ve grown since that very first week. At 15 – 16 weeks old, your baby might have chunky arms and thighs and neck rolls that require careful cleaning. As they get stronger, you can experiment with sitting them up in a baby seat or jumperoo to get them working those core muscles. Soon they’ll be able to keep themselves sitting upright and playtime starts to look a bit different.
Physical development milestones from 15 – 16 weeks
Your baby is growing stronger every day, reaching, grabbing, kicking, pushing and twisting like never before. Activity gyms are well name: every way they encourage your little one to move is a kind of exercise, building strength. Don’t be tempted to move on to the next stage of toys too soon – there’s still plenty of mileage to get out of the baby gym yet.
When you pull on your baby’s hands, you should find they have more stability than before and there may even be a moment where they can hold a sitting position. But don’t expect it to last long – that core strength takes a while to build. While they’re practicing, make sure you stay close and surround them with cushions or blankets to ensure a soft landing. Babies at this age shouldn’t be left on the floor unattended.
Meanwhile, rolling is still the main focus for most babies at this age – though you do get the rare one who will crawl before they roll, as if to keep parents everywhere on their toes! Rolling requires plenty of clear, comfortable floor space – and a bit of motivation. Toys might do it, but your baby is just as likely to roll towards you (or the family dog!), so get down to their level and keep offering plenty of praise and encouragement.
Milestone checklist
- Core strength – Your baby is building up to being able to sit unaided, working those tummy and back muscles while they play.
- Balance? Not yet – It will likely be a while before your baby can sit unaided, but you can help them practice by keeping hold of their hands and pulling them up to a sitting position. Try it while singing ‘row, row, row your boat’ – and if you see a crocodile, don’t forget to scream!
- Just keep rolling – Perhaps your little one has rolled once and never again, or maybe they’re rolling clear across the floor. Stay with them, encourage them, and make sure they have safe space to practice in.
Child brain development at 15 – 16 weeks
Some exciting things are happening in your baby’s brain right now. First, the short term memory is beginning to develop. What might this look like from your perspective? Well, your baby might remember that an object is somewhere – and look for it. So if you’re playing games like peek-a-boo or hiding an object behind your back, they can get much more involved. They might look delighted instead of just confused.
The second big development is happening in the part of the brain that controls senses such as taste and touch, as well as hand-eye coordination and visual recognition.
These developments are enhanced by environmental stimulation, meaning the more you play with your baby, and the more opportunities you give them to explore these tools, the more they develop.
Social & Emotional Development
You and your baby have got to know each other pretty well these last few months and by now you can probably tell when your baby is happy, when they’re uncomfortable, when they’re sad and when they’re furious. Their language is developing – in the form of multiple sounds and even sounds with more than one syllable to them – and they might use this language to communicate some of these feelings, though in all likelihood, they’ll only attempt this kind of communication when they’re feeling pretty relaxed. Angry babies usually just cry.
No doubt your baby will also have noticed how difficult it is for you to resist chatting back to them when they’re chatting to you – see if you can catch them starting up a ‘conversation’ or making sure they get the last word.
Sleep & Feeding
Rhythms and routines at this stage
Your little one is capable of going longer between feeds now and sleeping for longer stretches. But the new feed/sleep/play balance may be disrupted during this period – or shortly after – by what is known as a sleep regression. More on that in a moment.
For now, though, it’s worth watching how you respond to your baby’s cues. Try not to fall into the habit of feeding to pacify – particularly if they’re waking unexpectedly at night; first check to see if there might be something else your baby wants, like a fresh nappy or just reassurance. Feeding on demand is still important and encouraged, but it’s ok to first check that it’s definitely food your baby is after. Signs of hunger at 15 – 16 weeks old include chewing on hands, opening and closing their mouths, rooting against your body, or moving their head from side to side.
4-month sleep regression
Sleep regression is defined as a backwards step in a baby’s sleep patterns – e.g. they were sleeping for longer stretches, and are suddenly waking much more frequently, seemingly without cause. This is not to be confused with disrupted sleep caused by teething or illness. The 4-month sleep regression is thought to be a symptom of your little one’s increased awareness of the world around them – suddenly their little brains are busy all the time and they have a lot to process and lots to do.
In a sleep regression your baby may wake at night alert and playful, leaving you tearing your hair out. Just when you thought you’d got their routine sorted, suddenly you’re absolutely exhausted again. And naps might also suffer similarly, meaning there’s not even any respite during the day. The good news is, sleep regressions are temporary and your little one will find their way back to a better routine again. The bad news is, you have to just keep going through it.
One top tip for sleep regressions – some nights you just have to resign yourself to being up. It’s a lot less frustrating to give in to it, go downstairs and let them wiggle out some of that energy for a while, than it is to stay up half the night trying to persuade them back to sleep.
Staying sterile
If you’re using a bottle to feed your baby, you might be thinking that all this sterilising is unnecessary. After all, your little one is almost four months old now. But the NHS recommends sterilising baby bottles and teats for the first 12 months of their life to avoid exposing them to harmful bacteria, which could cause infection.
Note that putting feeding equipment through the dishwasher is not the same as sterilising it – you will still need to boil, steam, or use a cold-water sterilising solution to thoroughly clean your equipment.
Appointments in this period
It’s time for the 16-week immunisations and another two injections for your baby. Some parents find it easier now that they know what to expect, while others say it’s harder now that their babies are more aware of what’s going on. Either way, vaccinations are essential to keep your baby safe – and this is the last one for a while!
This time your baby will have their third dose of the 6-in-1 vaccine, which protects them against diphtheria, hepatitis B, Haemophilus influenzae type B, polio, tetanus and whooping cough, as well as the first dose of the pneumococcal vaccine, which helps protect against some types of meningitis, sepsis and pneumonia. They’ll have their second dose of this one at 12 months old.
Once again, have the infant paracetamol at the ready if your baby shows signs of fever or pain. Well done for getting them through these vaccines – it’s not pleasant but it is important.
Looking after yourself
It’s been a full-on 16 weeks since you gave birth and though your body has hopefully recovered somewhat, your immune system might be struggling. It’s not just the lack of sleep – breastfeeding can leave you feeling a little depleted and if you’re too busy parenting to eat well, that also has an impact.
Take a look again at your routine and see if there’s anywhere in the day you can build in some rest. That might mean handing over to your partner when they finish work, or going up to bed earlier to try and get another hour or two of sleep.
If you’re breastfeeding, make sure you keep up with your fluids to avoid dehydration. You should also be taking at the very least a daily vitamin D supplement and maybe also a postnatal vitamin if you’re not confident you’re getting all the essential nutrients from your diet.
Eating well can feel like more effort than you have the time for – but caring for a baby while you’re not feeling well is no picnic either. Make sure your partner is helping you to plan, shop for and prepare meals, and try to think about batch cooking and enlarging recipes where you can so that you can make healthy lunches out of your leftovers.
If your exhaustion goes beyond normal tiredness, or you’re losing or gaining weight in a way that doesn’t feel normal, book an appointment with your GP. Having a baby can trigger conditions such as postpartum thyroiditis, which requires treatment.
A Note on Development Milestones
Developmental milestones are guides – not deadlines. If your baby isn’t ‘keeping up’ with your friends’ babies, it isn’t an immediate cause for concern. Every child develops at their own pace. That being said, your health visitor and GP are there to support you with any queries you might have and will always be happy to see you with your baby if you have any worries.
