Your baby at 4 months: rolling, laughing and the four-month sleep change

What is new this month

Rolling starts — usually tummy to back first, sometimes both ways by the end of the month. From the day a baby rolls once, the changing table, the bed and the sofa all become places they can fall from. This is the month to move nappy changes to the floor.

The social side opens up: belly laughs, squeals, long babbling conversations with anyone who answers, and a baby who turns to your voice across a room. Hands find each other, then everything goes in the mouth — which is exploration, not necessarily teething.

Head control is steady now, and most babies push up on their forearms during tummy time and hold their head up when pulled to sit. Vision is nearly adult-quality, which is why a four-month-old is suddenly distracted by everything mid-feed.

The four-month sleep change

Around now, baby sleep permanently reorganises into adult-like cycles with lighter phases in between. A baby who slept in long stretches starts surfacing every 45 minutes to two hours and needs help to get back down. It is developmental, it is not a step backwards, and it does not mean anything is wrong with your baby or your feeding.

What helps: putting the baby down drowsy but awake at least once a day, so falling asleep is not entirely dependent on being fed or rocked; a short, identical bedtime routine; a dark room; and daytime naps protected rather than skipped, because an overtired baby wakes more.

What does not help: starting solids early to 'fill him up' — it does not improve sleep and the evidence is clear on that — or switching formula in the hope of a fix.

It settles over two to six weeks for most families. If everyone is exhausted, share the nights: the parent not feeding can do the settling and returning.

Feeding, and holding the line on solids

Milk is still the whole diet. Breastfeeding continues on demand; formula-fed babies take roughly 700-900 ml a day across four or five feeds. No water, no juice, no cereal in the bottle.

Distracted feeding is the month's classic complaint — the baby latches, hears a sound and pulls off with everything attached. Feed in a quiet dim room and expect night feeds to become the efficient ones.

Six months remains the target for starting solids for most babies. If yours is showing genuine readiness earlier — sitting with support, good head control, watching food intently, tongue-thrust gone — talk to your paediatrician rather than starting on your own. Our starting-solids guide covers the readiness signs.

Vaccination: the 14-week visit falls in this month for many babies. Keep it even if the baby has a mild cold, and take the MCP card.

When to see a doctor

The standing newborn rules still apply: any fever in a baby under three months means the hospital the same day; fast or laboured breathing, the chest sucking in, blue lips, a fit, a rash that does not fade under pressure, refusing feeds, no wet nappy for six to eight hours, or a baby who is floppy and hard to wake are all same-day emergencies at any age.

For this month specifically: no smiling or social response at all, not turning toward sound, a persistent head tilt, hands kept constantly fisted, stiffness or floppiness, no attempt to lift the head during tummy time, or losing a skill the baby had — all worth an appointment rather than a wait-and-see.

This article is general information, not medical advice, and is no substitute for personal medical advice. For any decision about your or your child's health, please consult your doctor.

Frequently asked questions

Q: My baby rolled onto her tummy at night and I keep turning her back. — Once a baby can roll both ways reliably, it is safe to leave her where she lands. Keep putting her down on her back to start, and keep the cot clear of pillows, quilts and toys.

Q: He wakes every hour now and only feeds back to sleep. — That is the four-month change plus a feed-to-sleep association. Break the association gently: feed a little earlier in the routine, and let someone else settle him for a few nights.

Q: Is drooling and chewing a sign of teething? — Often not this early. Salivary glands become active around now and everything goes in the mouth regardless. A first tooth can arrive any time from four to twelve months.

Q: Should I be worried that he is not rolling yet? — Not at four months. The window runs to about six months for rolling, and babies who spend more time on their back or in a carrier get there later. Give plenty of floor and tummy time.