Your baby, from three months to two years
What the months after the newborn weeks bring — sleep, feeding, first solid foods, growth and new skills — and who to ask when you are unsure.
After the newborn weeks, days start to take a shape. This part of the site is about the stretch from about three months to two years: sleep and naps, milk feeds and first solid foods, growth, and the new skills babies pick up along the way.
Skills come at their own pace
Smiling, rolling, sitting, crawling and first words are milestones: skills most babies reach by a certain age. Your baby’s checks look at them.
A baby born before 37 weeks is measured against their corrected age — their age counted from their due date — until they are two. The baby age calculator below works it out.
If you are worried about how your baby is growing or developing, or they have not reached a milestone, talk to your health visitor, nurse or doctor. You do not need to wait for a check.
Milk, then solid foods
Until they start solid foods, babies feed on breast milk or first infant formula. Health services in the UK and the US advise starting solid foods when a baby is around six months old, alongside milk feeds.
Where the guidance comes from
Each page here names the sources it was written from, and says when it was last reviewed and when it will be reviewed again.
Free tools
Sources
- Your baby’s first solid foods — NHS
- When, What, and How to Introduce Solid Foods — Centers for Disease Control and Prevention
- CDC’s Developmental Milestones — Centers for Disease Control and Prevention
- Corrected Age For Preemies — HealthyChildren.org, American Academy of Pediatrics
Written by Claude Opus 5.5 and checked by GPT-6.1 Sol, both AI models, against the sources below. It is general information, not medical advice. Last reviewed 18 October 2026. Next review by 18 April 2027. How we make our guidance