My 4 month old
From 4 months, your baby will quickly be learning to coordinate their body. They will have more control over what they do, their vision, touch and hearing will be much more developed, and they will start to move around much more. They can communicate much better too, and the amount of time they spend crying should have settled by now.
Your baby will still be gaining weight steadily — probably about 0.45kg to 0.56kg a month. Most babies have doubled their birth weight by the time they reach 4 months of age. Their bones will be growing fast and they will be getting longer.
Along with their physical growth, 4 month old babies are learning more about their place in the world. They will be starting to show an interest in solid food and many of their new skills are preparing them for chewing.
Your baby is now due for their next round of vaccinations which will be the same as their first round: 3 injections and the oral rotavirus vaccine.
Understanding baby growth charts
A growth chart helps you and your doctor keep track of how your baby is growing.
What can my baby do?
Your 4 month old will pick up objects with their fingers and thumb and will try to put their hands (and everything else!) in their mouth. This is normal and they are teaching their mouth new skills, as well as getting ready for solid food. Just be careful they don’t put anything small enough to fit inside their mouth completely, to avoid the risk of choking.
From 4 months of age, your baby's physical skills will really start to develop more noticeably. They will soon be rolling over, sitting up and some may even start crawling in the next few months (though most babies start crawling at around 9 months).
Your baby’s eyesight will be really improving and they will start to link what they see to what they hear, taste and feel.
Now you can really start to have fun with your baby. You can look into each other’s eyes, smile at each other, laugh and ‘talk’.
Babies at this age love looking at themselves in the mirror and might smile and talk to their reflection. Babies this age can also chuckle and show delight or excitement. They can also show emotions like anger and frustration and might whinge at times, rather than crying. You will get to learn your baby’s cues for being hungry or tired so you can respond to them.
By 4 months, many babies will try to copy sounds like, saying ‘ah-goo’ and squealing. They might even say ‘ma-ma’ or ‘da-da’ but don’t get too excited — they probably don’t connect these words with you.
How can I help my baby develop?
Keep on talking and reading to your baby to help them learn about language and communication. Use different tones and intonations in your voice, or different facial expressions to emphasise the story.
Your baby will love singing songs, reading books, playing with toys and listening to you making funny sounds.
It will help your baby if you develop a routine. If it works for both of you, do things in a similar pattern each day. This will help them to feel safe and secure.
It’s also a good idea to think about preparing your home for when they start moving around. It could happen soon!
Development problem signs
All babies develop at different rates.
At 4 months, talk to your doctor or maternal child health nurse if they:
- don’t seem interested in things around them
- don’t seem to know you
- aren’t making any voice sounds
- don’t open their fingers
- don’t kick their legs, or their legs are bent most of the time
- don’t follow an object with their eyes or make eye contact
- don’t turn when you speak to them, or they aren’t startled by a loud noise
- are unhappy or unsettled most of the time
Resources and support
If you are worried or would like to discuss any issues with your baby’s development, speak to your doctor or child health nurse.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
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Last reviewed: December 2022