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.
- Some babies roll one way near the end of this month, most often tummy to back, and the CDC does not expect it until 6 months.
- 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.
What the CDC checklist says at 4 months
Four months is a CDC checklist age. These are things most children, meaning 75% or more, can do by now.
- Social: smiles on their own to get your attention, chuckles when you try to make them laugh, looks at you or makes sounds to keep your attention
- Communication: makes cooing sounds like oooo and aahh, makes sounds back when you talk, turns their head towards the sound of your voice
- Thinking: opens their mouth when they see the breast or bottle if hungry, looks at their hands with interest
- Movement: holds head steady without support when you are holding them, holds a toy you put in their hand, swings at toys with their arm, brings hands to mouth, pushes up onto elbows or forearms while on the tummy
Rolling is not a four-month milestone
It is worth saying plainly, because four months is the age it gets attached to almost everywhere. Rolling appears on no CDC list until six months, and then only from tummy to back. The AAP puts the first rolls at around five.
So a four-month-old who does not roll is early rather than late, and one who does has simply got there ahead of the list. What this month's list actually watches is the groundwork: head control, hands to the mouth, and pushing up on the forearms during tummy time, which is the position rolling eventually falls out of.
When to raise something
The four-month checkup is the place. Worth mentioning: a head that still lags when your baby is pulled to sitting, no smiling at people, not bringing hands to the mouth, not watching things as they move, or not making any sounds other than crying.
As at every age, a consistent difference between the two sides of the body is worth a mention, and a skill that has gone away is worth a call rather than a wait.
Week by week, in the app
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
Read next
- Newborn Noises: Hiccups, Grunts, Sneezes and What Is NormalGrunts, squeaks, sighs, sneezes and hiccups are all listed by the AAP as ordinary newborn noise.
- When Do Babies Roll Over?Tummy to back usually comes first, at around five to six months.
- When Can Babies Start Solid Foods?The AAP recommends only breast milk for approximately 6 months, then foods alongside continued breastfeeding.
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.
Frequently asked questions
Later than this month, for most. The AAP puts the first rolls at around five months and the CDC does not list rolling from tummy to back until six, so a four-month-old who does not roll is early rather than late. What matters now is what it means for the crib: from the first roll, it holds your baby and nothing else, because they will not stay where you put them.
The change is real, but calling it a regression gets it backwards. Infant sleep reorganises around this age into lighter and deeper stages, so your baby now surfaces several times a night the way adults do. It does not reverse, which is why the nights tend to settle again once falling asleep at the start of the night is something your baby can do.
Roughly 12 to 16 hours per 24, naps included, and healthy babies sit either side of that. How the hours are spread matters less than whether your baby wakes rested and feeds well.
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.