The Masterpiece Mom

Home » Misc » What is percentile in pregnancy

What is percentile in pregnancy


Understanding baby growth charts | Pregnancy Birth and Baby

Understanding baby growth charts | Pregnancy Birth and Baby beginning of content

6-minute read

Listen

Baby or infant growth charts show how your child is growing. It's important not to compare your baby's size with that of other babies since this may be misleading. The most important thing is that your baby is healthy, happy, and growing appropriately.

What is an infant growth chart?

An infant growth chart helps you, your doctor and other health professionals keep track of how your baby is growing.

Your baby’s growth is a good indicator of their overall health and nutrition. This is done by comparing your baby's growth with that of other babies of the same age. There are different charts for:

  • males and females
  • infants and older children

Growth charts record changes in your baby's measurements, including their:

  • length (height)
  • weight
  • head circumference

These measurements are recorded on the chart so you can see how they change over time. On the vertical (up-and-down) axis is the measurement; on the horizontal (side-to-side) axis is the baby's age.

There will probably be a growth chart in your child's personal health record. Depending on where you live, this record is known by different names. In New South Wales, it is the Blue Book. In Queensland, it is the Red Book. Your child and family health nurse or doctor may also keep a growth chart.

Infant growth (aged 0 to 2 years) is usually calculated using the World Health Organization's (WHO) growth standards.

Most states and territories use growth charts based on those from the US Centers for Disease Control.

What are percentiles?

Like adults, babies come in all shapes and sizes. The growth charts show this by using 'percentiles'. Below are some examples:

  • A baby on the 50th percentile for weight is right in the middle of the normal weight range: 50% of babies their age are lighter, and 50% are heavier.
  • A baby on the 5th percentile weighs less than 95% of other babies of that age.
  • A baby on the 90th percentile weights more than 90% of other babies that age.

Some babies will always be small. Others will always be large.

All babies grow at different rates, and 'normal' growth varies a lot. The important thing is that your baby continues to grow at a similar rate.

The WHO's infant growth chart for girls aged 0 to 2. The WHO's infant growth chart for boys aged 0 to 2.

How are the growth charts used?

Growth charts will help you track how your baby is growing by showing normal growth curves (i.e., always increasing). You can plot your baby’s growth to see if it follows a similar pattern to other babies on that percentile.

Your baby is weighed and measured at birth and then when they are 2 weeks old. After that, their growth is best tracked by measuring them every month until they are 6 months old. Don't worry if their weight goes up and down a bit from day to day — this is normal.

Growth charts are used until your child turns 18.

You can talk to your child health nurse or doctor about other health checks to make sure your child is growing and developing normally.

How will my baby be measured?

Special infant scales are used to weigh babies under 2 years old. Newborns lie down on these scales. It’s more exact to weigh babies with no clothes on until they are 12 months.

After they turn 2, they are measured standing up in light clothes. You baby's head circumference is measured using a tape measure.

If your child was born prematurely, their age is 'corrected'. This means their age is adjusted to account for the number weeks that they were born prematurely. This is done by taking the number of weeks early they were away from their birth age. This corrected age is recorded on all their growth charts. This will continue until they turn 2 years old.

When should I be worried?

It’s important to measure a baby’s growth to see if they are healthy and developing properly. Parents are often worried that their baby isn't growing fast enough. However, it's not the only way to tell if they're healthy.

All babies lose some weight in the week after birth. They usually regain this weight by 2 weeks. Most babies double their birth weight by 4 months.

Male babies usually triple their weight by 13 months. Female babies usually triple their weight by 15 months.

There is unlikely to be anything wrong if your baby:

  • has at least 5 very wet nappies each day
  • has pale urine (wee)
  • does well-sized, soft poos
  • has good skin colour and muscle tone
  • is meeting other developmental milestones

Weight gain can be affected by an infection or vomiting. If you are ever worried, talk to your child and family health nurse or doctor.

If your baby’s growth percentile changes a lot – by 2 major percentile lines - talk to your child and family health nurse or doctor. They will assess the child's growth trend to see if there is any reason to be worried.

Remember, don't compare your baby’s growth to that of other baby’s. The important thing is that they continue growing following the same percentile.

Where can I get more information about baby growth charts?

If you have any questions about your baby's growth or development, you can call Pregnancy, Birth and Baby on 1800 882 436. Or see your child's doctor or early childhood nurse.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Sources:
Australian Breastfeeding Association (Baby weight losses and weight gains), World Health Organization (Child growth standards), National Children’s Digital Health Collaborative (Child Digital Health Record Digital Baby Books), Healthy Kids for Professionals (Guide to accurately weighing children using infant scales), Healthy Kids for Professionals (Guide to accurately weighing children using standing scales), Child and Adolescent Health Service (Growth – birth to 18 years), The Royal Children's Hospital Melbourne (Clinical Practice Guidelines: Slow Weight Gain)

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: July 2022


Back To Top

Need more information?

Growth charts for babies & children | Raising Children Network

Child growth charts give a guide to how well children are growing. Growth usually follows a typical pattern, which is influenced by genes and environment.