This is a question I get asked a lot, usually by parents who are weighing more often than they need to and feeling worse for it.

The short answer

From around 6 to 12 months, it is recommended that growth can be measured every two months.

But most children do not even need to be measured this much, because most are growing perfectly fine.

Why more often is not better

If you weigh children too often, it can be misleading and create parental anxiety.

Growth fluctuates up and down over the months, and all children grow at very different rates. Frequent weighing captures that normal variation and presents it as though something is happening, which is unsettling to look at and rarely means anything.

So we do not encourage very frequent weighing, unless it is something you have specifically been asked to monitor.

What normally happens

Your baby is weighed at birth, then again within the first two weeks of life to check they are regaining their birth weight. Some babies never lose it and just keep gaining.

After that, the health visitor checks weights infrequently, unless you are attending hospital for regular appointments or there are concerns about growth.

Premature infants have their own growth charts, with growth corrected according to how premature the infant was, until the age of two.

Getting an accurate measurement

If you are going to measure, the technique matters.

In the under twos, babies should be measured lying down with no clothes or nappies, for both weight and length. A length board is normally used, because length is very difficult to measure accurately without one, which is why it is usually done in a professional setting.

Home scales with a baby in a vest are not measuring the same thing, and comparing those numbers to a chart plot taken properly will mislead you.

What actually warrants a look

There are specific changes worth acting on:

• A drop of more than two centiles.
• Growth below the 0.4th centile, which is the very bottom line on the chart.

Both of these are reasons to seek advice from a professional.

What is not a red flag is your child sitting one centile above or below on weight compared to height. That is absolutely fine.

A note on BMI

We do not look at body mass index in the under twos. BMI cutoffs are very different for children than for adults, and there are specific charts for looking at it, but it is mainly considered in the context of obesity.

If the weighing is anxiety rather than monitoring

This is worth being honest with yourself about. If you are weighing your baby frequently because you are worried they are not eating enough, the scales are unlikely to settle that worry, and the fluctuation you see may well make it worse.

Most babies are really good at regulating their own appetites. Feeding responsively and looking at the whole week rather than individual days is generally more useful than another number.

If you are genuinely concerned about growth, that is a conversation with a professional rather than something to resolve on your own bathroom scales.