Your 4-Month-Old: Rolling, Laughing and Hands That Finally Meet
By the Growbaby team · Published Aug 4, 2026
Written against AAP, CDC and WHO guidance. How we write these guides
At a glance
- Hands find each other at the midline, which is the start of two-handed play.
- Many babies roll one way this month, most often front to back first.
- The first proper laugh often arrives around now.
- Sleep architecture matures around 4 months and does not change back; this is the change behind the so-called regression.
- Typical sleep is 12 to 16 hours per 24, naps included.
Month four is when your baby starts to look less like a newborn and more like a small person with opinions. Hands come together in the middle, which sounds minor and is not: it is the beginning of holding one thing with two hands, and of bringing whatever they are holding somewhere useful.
This is also the month sleep famously changes. It is not a step backwards. Infant sleep reorganises around now into something closer to the adult pattern, which means your baby surfaces into lighter sleep several times a night and notices the room is different from how they fell asleep.
What is new this month
Hands meeting in the middle is the quiet headline. Until now each hand worked its own side; bringing them together at the midline is what makes holding one object with two hands possible, and it is the groundwork for passing something from hand to hand later in the year.
The sleep change that gets called a regression is really a maturation. Infant sleep reorganises around this age into a pattern with lighter and deeper stages, so your baby now surfaces several times a night the way adults do. Adults return to sleep without noticing; a baby who was fed or rocked all the way down notices the room has changed and says so.
Week by week, in the app
Our paediatric specialist wrote one thing to notice and one thing to try for every week of the first three years. Here is what this month covers. The app works out which week your child is in from their birth date and brings each one to you on the day.
- Week 14Your baby is Bringing Their Hands Together
- Week 15Your baby is Starting to Roll
- Week 16Your baby is Laughing Out Loud
- Week 17Your baby is Sustaining Attention
This week, for your baby
Growbaby works out which week your baby is in from their birth date and brings that week's activity to you on the day, so you are not looking up where you are. Plus adaptive soothing for the nights and Growy for the questions in between.
This guide is for general informational purposes only. Growbaby is not a medical device and does not provide medical advice, diagnosis or treatment. Every baby develops at their own pace; for any question or concern about your baby's health or development, always consult your pediatrician or another qualified healthcare provider.