The new dot for your baby's head measurement looks higher than the last one. It is easy to jump from “the line moved” to “something is wrong”. Take a breath: one number cannot tell you why a line moved. Ask your health visitor or GP to confirm the measurement, check that it was plotted on the right chart and look at the trend alongside your baby's health. Do not change feeds or start repeated home measurements to chase a centile.
If your baby seems very unwell, is difficult to wake, has repeated vomiting, or the soft spot on their head looks swollen or bulging, seek urgent medical help rather than waiting for a routine growth review. The NHS lists a bulging fontanelle among signs that need urgent attention.
This is general information for parents, not a diagnosis. Follow your child's own clinical plan if they were born early or are already being monitored.
What does a head centile actually tell you?
Head circumference is the distance around the widest part of a baby's head. A centile compares a measurement with a reference for children of the same age and sex. It is not a score, and the middle line is not a target.
The Royal College of Paediatrics and Child Health (RCPCH) explains that UK children can have relatively large heads compared with the WHO standard, particularly after six months. A head measurement near the top of a chart, by itself, does not tell you that a baby has a condition. What needs professional attention is a continuing rise through centiles or concerning signs and symptoms.
That does not mean every upward move should be ignored. It means the right response is to check the measurement and the child—not to diagnose from a screenshot of the chart.
Three checks before you interpret the new dot
1. Was the measurement comparable?
Write down the exact value, date and where it was taken. The RCPCH says growth measurements and plotting should be done by someone suitably trained, and that age errors are a common plotting error. A clinician can check the tape placement, the recorded units and whether the point belongs on that part of the chart.
If the surprising number came from a home tape, treat it as a reason to ask for a proper check—not as a new diagnosis or a prompt to measure every day.
2. Is it the right chart and age?
In the UK, the Red Book uses UK-WHO growth charts. A baby born early may need a preterm chart or corrected-age plotting. The RCPCH's parent FAQ explains that this depends on how early the baby arrived. Bring the Red Book and let your health visitor or neonatal team interpret it; do not try to correct the plotted age yourself.
3. Is it a one-off point or a continuing pattern?
Ask how this value compares with earlier professionally measured points. Is the head measurement continuing to rise across centile spaces, or does one dot need confirming? The RCPCH advises assessment when the head centile keeps rising or there are other concerning signs. There is no safe app-only rule that settles that question for an individual child.
When to call, and when not to wait
| What you notice | Next step | |---|---| | One unexpected number, baby otherwise well | Contact your health visitor or GP to check the measurement and chart; do not repeatedly remeasure at home | | A confirmed upward trend across visits, or a concern about head shape or development | Arrange a professional review and bring the dated measurements and Red Book | | Bulging or swollen soft spot, unusual drowsiness, repeated vomiting, or a baby who seems seriously unwell | Seek urgent medical help now; use NHS 111 for urgent advice or 999 in an emergency |
The NHS urgent-help guide is the place to check other warning signs. Trust your instincts if your baby seems different or unwell. A chart is never a reason to delay care.
What to bring to the conversation
You do not need a spreadsheet of every day. A useful note is:
- each head measurement with its date and who took it
- the Red Book or clinic chart used
- whether your baby was born early and has a specialist growth plan
- any change in feeding, vomiting, alertness, development or head shape that worries you
- the specific question you want answered: “Does this need another measurement or any follow-up?”
If you have several concerns, our health visitor appointment guide helps turn them into a short list you can actually use in the room.
Where OBubba fits—and where it stops
In the current app, Grow → Growth lets you save a dated head-circumference measurement alongside weight or length. OBubba can display the values and a WHO-based growth view. It cannot check how the tape was placed, examine your baby or replace the UK's Red Book and a clinician's interpretation. A WHO-based app centile and a UK-WHO Red Book centile should not be treated as interchangeable.
If you log a professional measurement, keep its date and units accurate. You can use the record to remember what was measured and when, then ask your health visitor about a surprising change. You do not need to fill the gaps with daily home measurements. Our guide to weighing frequency explains why more points are not always more clarity.
Keep dated growth records together in OBubba →
The reassuring answer is not “the app says it's fine”. It is: “we checked the right measurement with the right professional, and we know what happens next.”
Ready to try OBubba?
Use OBubba to track feeds, sleep, naps, nappies, growth, milestones and family handovers in one calm baby tracker app.