MaxieGuide · Growth
WHO growth percentiles, explained in plain English
A percentile compares your baby with a large group of healthy babies of the same age and sex. The 50th is the middle. The 10th isn't a bad mark and the 90th isn't a good one. Health professionals watch the line your baby follows over time.
Not medical advice. This page summarises what Australian and New Zealand health services publish, and links to them. It is general information, not advice about your baby. If you are worried, speak to your midwife, child health nurse or GP, or call Healthdirect on 1800 022 222 (PlunketLine 0800 933 922 in New Zealand). In an emergency, call 000 (111 in New Zealand).
Which charts Australia and New Zealand use
From birth to two, babies' growth in Australia is plotted on the World Health Organization growth standards, as Raising Children Network and Pregnancy Birth and Baby both explain. The WHO standards describe how healthy children grow from birth to five when their needs are met, based on children in six countries. New Zealand's Well Child Tamariki Ora book uses WHO-based charts too.
What the number means
Picture 100 babies of the same age and sex, lined up from lightest to heaviest.
- 50th percentile. Right in the middle. Half are lighter, half heavier.
- 10th percentile. About 10 of the 100 are lighter.
- 90th percentile. About 90 of the 100 are lighter.
As Pregnancy Birth and Baby puts it, babies on low and high percentiles can both be in the typical range. Someone has to be on the 5th, and someone on the 95th.
The line matters more than the dot
One measurement is a snapshot. Scales differ and babies wriggle. That's why the NSW Blue Book says to record several measurements over time to see the trend. Many healthy babies stay near one curve, and some drift, especially early on. Whether a change matters is one for your child health nurse or GP.
Three charts, three percentiles
Weight, length and head circumference each have their own chart, and a baby can sit on different percentiles for each. A long, lean baby might be on the 75th for length and the 40th for weight. That's fine.
What a percentile is not
- Not a score. Higher is not better.
- Not a prediction of adult height or weight.
- Not a diagnosis. Only a health professional who has examined your baby can say whether growth is on track.
When to ask
Worried, or surprised by a measurement? Ask at the next check or sooner. Your child health nurse, GP or Healthdirect (1800 022 222) can help; in New Zealand, your Plunket nurse or PlunketLine (0800 933 922).
Seeing the line, not just the dot.
Maxie plots weight, length and head circumference on the WHO curves for your baby's age and sex, so you both see the same chart before the appointment. The percentile is there as a reference. It's free.
Sources
Read on 25 September 2026. Health advice changes, so trust the linked page.
- Raising Children Network: Children's growth charts (Australian Government funded)
- Pregnancy Birth and Baby: Understanding baby growth charts (Australian Government, Healthdirect)
- NSW Health: My personal health record (Blue Book) (PDF, includes the growth charts)
- Whānau Āwhina Plunket: Your appointments, what to expect (New Zealand)
- World Health Organization: Child growth standards
More guides: how many wet nappies · newborn feeding log.