What milestones should a 4-month-old have?

Most babies do these by 4 months (CDC): Smiles on their own to get your attention · chuckles when you try to make them laugh · looks at you, moves, or makes sounds to get your attention · coos ("oooo", "aahh") · makes sounds back when you talk · turns head toward your voice · opens mouth when hungry and seeing breast or bottle · looks at their hands with interest · holds head steady without support · holds a toy placed in their hand · swings arm at toys · brings hands to mouth · pushes up onto elbows when on tummy.

Back to your baby's forecast

Month 4 of 12 · Window 2 · Waking up to the world

Your 4-month-old baby: milestones and what to expect

Four months brings the famous "sleep regression" — really your baby's sleep maturing into adult-like cycles — plus the CDC's 4-month checklist: steady head, turn-taking sounds, hands discovered and inspected at length.

Checked against CDC, NHS and AAP guidance · how we fact-check

Most babies do these by 4 months (CDC)

What most babies this age can do

Social & emotional: Smiles on their own to get your attention · chuckles when you try to make them laugh · looks at you, moves, or makes sounds to get your attention.

Language & communication: Coos ("oooo", "aahh") · makes sounds back when you talk · turns head toward your voice.

Movement & thinking: Opens mouth when hungry and seeing breast or bottle · looks at their hands with interest · holds head steady without support · holds a toy placed in their hand · swings arm at toys · brings hands to mouth · pushes up onto elbows when on tummy.

What you might notice

The 1992 research described fussy clusters around weeks 8 and 12: more crying, more clinging, sometimes lighter sleep or fussier feeds for a few days. On the bright side, this is when social smiles and first chuckles usually bloom.

What can help this month

A loose day and night rhythm is starting, but this is not the moment to force a strict schedule. Talk, coo, and pause for a reply: babies this age love the back-and-forth and it builds language early. If sleep gets choppy again during a fussy stretch, it is usually temporary, not something you caused or need to fix.

And you: Choppy sleep during a fussy stretch is the baby, not your parenting. Tag-team the nights if you can, and lower the bar on everything that is not feeding and cuddling.

Talk with your pediatrician if…

Talk with your doctor

Your baby is missing one or more of the milestones above by 4 months, or has lost skills they once had. That is the CDC's own advice: don't wait, talk with the doctor and ask about developmental screening. And if you're simply worried, that's reason enough to call.

Coming up: after this window comes "grabbing everything" (weeks 17 to 26). No deadlines — windows.

Week by week, if you want the detail

This month roughly covers week 14 · week 15 · week 16 · week 17. Each page has that week's specifics on your baby's calendar.

Want the personal version?

This page covers what's typical at 4 months in general. For your own baby's map — including adjusted age for premature babies — run the free forecast.

See my baby's exact forecast

Sources: CDC milestone checklists (2022 revision) · Zubler et al., Pediatrics 2022 · van de Rijt-Plooij & Plooij, 1992 (via KNAW review) · Sadurní & Rostan, 2002. Timing varies a lot between babies — windows, not deadlines.