GROWTH & DEVELOPMENT
A new dot in the Red Book. A new move on the mat.
The Red Book shows measurements; everyday play shows new attempts. A fussy week might leave you wondering how the two fit together. These articles help you explore growth and development one question at a time.
Prepared by Nerumi · Sources checked 23 September 2026
What do the lines in the Red Book mean?
A dot on a chart can draw your attention straight to the number. Start with how centiles work, then look at what it means when a measurement moves between lines.
How to read your baby's growth percentiles
Understand the idea behind a centile, why measurements need context and what a series of results can show.
Understand growth-chart numbersFor the UK-specific questions, continue with how the Red Book is used in growth reviews.
Red Book Centiles: What Does Crossing a Line Mean?
Explore changes between centile lines and the details a health visitor or GP considers alongside the chart.
Read the Red Book guideIs this a growth spurt, or just a different few days?
More feeding, broken sleep and fussiness can arrive together. Before putting them all down to growth, look at what the label can and cannot tell you.
Baby growth spurts: what can you actually tell?
Read about measured growth, popular leap calendars and the observations worth bringing to a conversation about your baby.
Explore growth-spurt questionsWhat are people describing as the “8-week leap”?
A more alert baby, closely spaced feeds, harder evenings: which part sounds familiar? This UK article unpacks the questions without assuming they all have one explanation.
Is There an Official 8-Week Leap? What UK Guidance Says
Explore changes around two months, what is discussed in early reviews and when not to dismiss a concern as a leap.
Look at the changes behind the labelShould my 6-month-old be sitting or crawling?
It’s easy to compare when another baby is already on the move. This guide looks at progress across different movements and the questions to raise if something concerns you.
Should a 6-Month-Old Be Sitting or Crawling? UK Guide
Read about supported sitting, crawling and opportunities for movement, with UK resources and advice on speaking to your health visitor or GP.
Explore sitting and crawlingUnsure when the next review will be?
The UK review timetable article explains why invitations differ across the four nations. You can contact your health visitor or GP about a concern between routine reviews.
Sources and official guidance
These resources support the topics on this page. The linked articles include sources for their detailed guidance and identify national differences where relevant.
- NHS — Your baby’s weight and height: Growth charts, centiles and weighing.
- NHS — Your baby’s health and development reviews: The Red Book, reviews in England and raising concerns between appointments.