Start with your child
This timeline helps you understand changes you may notice and find things to try together. Your baby will not show every skill or behaviour in a chapter at once. The ages give you useful context for conversations with your health visitor or doctor.
What the ages mean
- By a stated age: a milestone most children are expected to reach by then. The CDC uses ages by which about 75% or more of children would be expected to show a skill.
- Across an age range: a skill can develop over several months. WHO’s movement studies show these wider ranges.
- A general pattern: something seen across groups of babies, such as more crying in the early weeks. It cannot predict an individual baby’s day.
- Everyday advice: something you can do, such as responding to hunger cues. Sleep-hour recommendations also belong here; they are not measured averages.
The weeks help you find your place in the timeline. They do not mean a change will happen in that exact week. If a skill is missing at its stated age, your child loses a skill or you have a concern, ask a health professional. You do not need to wait for the next chapter. Read how the CDC uses milestones.
Where the information comes from
We use guidance and research from organisations including WHO, the CDC, the NHS and NICE. Open “Sources” within a topic to see the specific guidance behind it. The full source list gives links and dates for the editorial checks.
An activity such as talking during a cuddle is a way to put guidance into practice. It is not a test or a promise that a skill will develop sooner. Source notes distinguish recommendations from research findings and broader observations.
Confidence labels describe our editorial confidence that a statement reflects its source. They do not rate your child, predict an outcome or replace a clinical assessment. A strong recommendation can still be based on limited research.
If your baby was born early
Corrected age counts from the expected due date and can help you understand developmental timing after birth before 37 completed weeks. This site shows it for relevant developmental notes until the second birthday. Your care team may continue follow-up beyond that point. The corrected-age guide explains the calculation and its limits.
Advice where you live
Some advice applies widely; other recommendations and services depend on your country. Practical NHS and NICE guidance is identified as UK guidance. Elsewhere, follow local health advice and any individual plan from your child’s care team.
Your details stay private
Your browser uses the birthday, optional name and due date to personalise the timeline. These details stay on your device and are not sent to us. If your browser cannot save them, they are kept only for that visit. Choose “Clear saved details” on the timeline whenever you want to remove them.
Sharing a chapter shares its public link and activity, without your baby’s details. You can also read every chapter without entering anything.
Checks and limitations
Source pages can change after we check them. A checked date records an editorial source check, not a clinician’s approval. This site has not had a named clinical review and is general information, not a tool for diagnosing or assessing your child. Use your care team’s advice if it differs from a general note here.