3 Months Old: Development, Milestones, and the End of the Fourth Trimester

Three months is often described as the end of the fourth trimester — the unofficial twelve-week period where your newborn is still adapting to the world outside the womb. By now, most babies are more predictable, more interactive, and frankly more fun than they were in those first hazy weeks. You may also, for the first time, be getting the occasional four or five-hour stretch of sleep.

Motor Development at Three Months

Rolling Attempts

Many babies will start attempting to roll around three months, though full rolling typically happens between four and six months. What you'll see now is the beginning of that movement: your baby shifting their weight and arching their back during tummy time, or rocking side to side on their back. Make sure you're never leaving them unattended on any elevated surface — change tables, sofas, or beds — even if they haven't rolled yet.

Grasping

The palmar grasp reflex is still present, but you may start to see your baby beginning to reach toward objects deliberately. They'll start swiping at things in front of them — a hanging toy, your hair, your face. Their hands are open much more of the time now.

Head and Trunk Control

Neck and upper body strength has grown significantly. During tummy time, many three-month-olds can push up onto their forearms and hold their head at 45 to 90 degrees for a sustained period. When you pull them gently from lying to sitting, there's noticeably less head lag than a month ago.

Social and Communication Development

Laughing Begins

One of the most joyful milestones: the first laugh. Not all babies laugh by exactly three months — some hold off until four months — but many will produce their first chuckle around this age. It's often triggered by tickling, funny faces, or a favourite game. Once it happens, you'll spend an inordinate amount of time trying to make it happen again.

Recognising Faces and Voices

Your baby now clearly recognises your face and voice and will respond differently to familiar people than to strangers. They'll quieten to your voice from across the room and may turn their head toward a sound they recognise.

Two-Way Conversation

The serve-and-return interaction from last month is becoming more sophisticated. Your baby will now hold your gaze, coo and babble, wait for your response, and then vocalise again. This is foundational language development. Talk back, mimic their sounds, and give them time to "reply."

Feeding at Three Months

Feeding is usually more settled by three months than it was in the early weeks.

Breastfeeding: Many women find their supply has regulated by now and the supply-and-demand system is working smoothly. Feeds may feel shorter — a ten-minute efficient feed is fine; it doesn't mean supply is low. The three-month growth spurt can cause a sudden increase in feeding frequency for a few days. Ride it out by feeding on demand.

Formula feeding: Most three-month-olds take around 150–180 ml per feed, approximately every three to four hours. Total daily intake is typically around 150 ml per kilogram of body weight.

Introducing a bottle to a breastfed baby before this point is generally easier than after — if you're planning to return to work or want a partner to occasionally take a feed, now is a reasonable time to try.

Sleep at Three Months

Sleep is beginning to mature, but it is still nowhere near the sleep of an older baby or toddler.

Some three-month-olds will have longer stretches at night — five to six hours is achievable for many, and some babies will sleep seven or eight hours. Others still wake every two to three hours. Both are within the range of normal.

Daytime naps are still somewhat unpredictable. Three to four naps a day is typical, ranging from short catnaps of twenty minutes to longer stretches. If you haven't already, this is a reasonable time to start laying the groundwork for a simple bedtime routine — bath, feed, song, sleep. You don't need to be rigid about it, but a gentle, consistent sequence helps signal that night is coming.

The Three-Month Growth Spurt

Growth spurts at around three months are very common and can catch families off guard. Your baby may suddenly feed much more frequently, wake more at night, and seem fussier than usual. It typically lasts two to four days. If you're breastfeeding, the best response is simply to feed more often — your body will increase supply to match.

Emerging Routine

By three months, many families start to notice a natural pattern emerging in their day — not a strict schedule, but a general rhythm of feeding, awake time, and sleep. This is worth noticing and gently encouraging. A loose routine reduces stress for both of you and starts building the foundations for healthy sleep habits later.

Awake windows at three months are typically 60–90 minutes. Much longer than that and your baby is likely heading toward overtiredness, which makes settling harder.

What to Mention to Your Health Visitor

Speak to your health visitor if:

• Your baby is not smiling socially by three months
• There are no vocalisations — no cooing or gurgling sounds
• Your baby doesn't seem to track moving objects with their eyes
• Head control is very poor — no lifting during tummy time, persistent head lag when pulled to sitting
• You notice anything asymmetrical about the way they move — one side consistently weaker than the other
• You're struggling yourself — postnatal depression and anxiety can develop or persist well beyond the first few weeks

Looking Ahead

Four months brings rolling, laughing reliably, and the much-discussed sleep regression. The next few months are a period of rapid change — enjoy the relative calm of three months if you're in it, and know that whatever difficult phase you're in now won't last.