3-Month-Old Baby Guide: Sleep, Feeding, Development & the 12-Week Jabs

What may change around three months?

You may see more eye contact, cooing that turns into a back-and-forth exchange, hands travelling to the mouth and early swipes towards toys. During tummy time, lifting the head and upper chest may look easier. Head control is strengthening, but continue supporting the head and neck until it is reliably steady.

The NHS does not use a separate three-month development checklist. This age sits between early newborn skills and the abilities that usually become clearer towards four months. Babies born early are assessed using corrected age. There is no prize for reaching a skill first; what matters is progress over time. A skill that disappears, however, should always be discussed promptly with your GP.

What happens at the 12-week vaccination appointment?

For babies following the current UK schedule, the 12-week appointment includes the second 6-in-1 vaccine, the second rotavirus dose and the second MenB dose. The schedule changed for babies born on or after 1 July 2024: pneumococcal vaccine is now given at 16 weeks rather than 12 weeks. Older web pages or a sibling’s record may therefore look different.

There is no separate universal three-month development review after the 6–8 week check, although your GP or health visitor may arrange follow-up for an individual concern. Use the Red Book and the invitation from your GP surgery as the final timetable. Ask at the appointment what reactions to expect and when to seek advice.

How much should a 3-month-old sleep?

The World Health Organization gives 14–17 total hours in 24 hours, including naps, for babies up to three months. From four months the reference becomes 12–16 hours. These are broad ranges, not targets. The NHS notes that some babies aged three to six months may sleep five to eight hours or longer at night—but ‘some’ is important, and waking to feed is still common.

About 75–120 minutes awake is a useful planning range for many babies in weeks 13–16. It is not a clinical rule. The broad age estimate becomes much more useful when narrowed with your baby’s own records: morning windows may differ from evening ones, and patterns become visible across several days. Use the estimate together with early signs such as looking away, slowing down, yawning or becoming unsettled.

Longer nights, short naps and the ‘3-month regression’

A longer first stretch at night may appear this month, but it is not a requirement. Brief naps and frequent night feeds can remain normal. Continue any feeding or waking plan given because of prematurity, weight gain or a medical condition; do not remove night feeds solely because the calendar says three months.

No UK clinical programme defines a universal three-month sleep regression or developmental leap beginning on a fixed week. A change in your baby is still worth taking seriously. Compare several days rather than applying a label: is the baby awake longer, feeding differently, waking in discomfort or simply moving sleep to another part of the day? A reliable record helps make that distinction.

Feeding changes and when to start solids

A three-month-old may feed more efficiently, become distracted by the room or ask for several feeds close together. A shorter breastfeed does not on its own mean low milk supply. Comfort, audible swallowing, the wider pattern of wet nappies, alertness and growth all matter.

The NHS recommends introducing solid foods from around six months, when the baby shows the combined readiness signs—not at three months and not simply because milk feeds have changed. Continue breast milk or first infant formula as the main food. Ask for support if feeding is painful, intake or wet nappies drop noticeably, your baby repeatedly struggles to coordinate sucking, swallowing and breathing, or feeds are accompanied by sweating, breathlessness or colour change.

Hands, dribbling, rolling and everyday play

Hands in the mouth and extra dribbling are common at this age and do not, by themselves, prove teething. Do not put a fever or an unwell baby down to teeth without seeking advice. Rolling may begin without warning, but a baby is not late for not rolling at three months. Never leave your baby alone on a bed, sofa or changing table.

Face-to-face talk, copying sounds, a light toy within reach and short supervised tummy-time sessions are enough. Tummy time is for awake play. For every sleep, place your baby on their back in a clear, flat, separate sleep space.

Growth is a pattern, not a target weight

WHO standards show a broad distribution at three months: approximately 5.1–7.9 kg for boys and 4.6–7.4 kg for girls covers the 3rd–97th percentiles. These are not ‘correct weights’. Birth history, length, head circumference, family build and earlier measurements all matter.

The Red Book curve is useful because it shows direction over time. One measurement or one centile crossing does not diagnose a problem; your GP interprets it alongside feeding, health and examination. If growth worries you, ask your health visitor or GP rather than repeatedly weighing at home.

When should you seek medical help?

Call 999 for severe breathing difficulty, blue or grey colour, a seizure, unusual unresponsiveness or another life-threatening emergency. Contact NHS 111 or your GP promptly if your baby cannot feed, has repeated forceful vomiting, has far fewer wet nappies, or seems substantially different from usual. Because this guide crosses the under-three-month fever boundary, report a temperature of 38°C or above promptly and give the baby’s exact age and how it was measured.

Loss of a skill, persistent asymmetry, very poor head control as four months approaches, or little response to sound are also reasons to discuss development. You do not have to diagnose the problem before asking for help.

Vaccinations

United Kingdom

• DTaP-IPV-Hib-HepB (6-in-1)Dose 2
• Meningococcal B (MenB)Dose 2
• RotavirusDose 2

This schedule is for reference. Which vaccine your child needs and when is your doctor's call.

Schedule: UK Health Security Agency · GB-UKHSA-2026-01 · reviewed 2026-08-09