How to Understand Your Baby’s Growth (Without Stressing About It)

Why every baby grows at their own pace

No two babies grow the same way — and that’s exactly how it should be. Whether your little one starts off chunky or petite, it’s normal for a baby’s growth to ebb and flow in the first year. What matters most isn’t how your baby compares to others, but whether they’re developing steadily over time and generally thriving.

In the first few days after birth, it’s completely normal for babies to drop a little weight. That initial loss usually turns around by the end of the second or third week, when most babies return to their birth weight or even surpass it.

Once past that early stage, many babies follow a gradual upward trend:

• From 1 to 3 months: Around 450g (1lb) a month
• 3 to 6 months: Between 400g and 600g (about 0.9–1.3lb)
• 6 to 12 months: Roughly 280g to 360g (0.6–0.8lb) monthly

But don’t get too hung up on the numbers — some babies grow in quick spurts, then take a breather. Others take their time, growing in quiet, steady increments.

What baby growth charts really tell you

You might have seen those curved lines in your baby’s red book (also called the personal child health record) — they’re called centile charts, and they help track your child’s weight, length, and head circumference over time.

If your baby’s growth is following one centile line fairly consistently — whether it’s the 25th, 50th, or even the 9th — that’s usually a sign that everything’s on track. What’s more important than the number itself is the pattern.

Sometimes, a baby might cross one centile line up or down — that’s not usually cause for concern. But if their measurements drop (or jump) across two or more lines, that’s when it’s worth checking in with a health visitor to explore further.

When to seek advice about your baby’s growth

Most babies are gaining weight as expected and have no trouble feeding, sleeping, and meeting milestones. But there are times when it’s wise to get a professional opinion.

Speak to your health visitor or GP if:

• Your baby isn’t gaining weight for a few weeks in a row
• They’re falling below the lowest centile on the chart
• They seem listless, lethargic, or less alert than usual
• They’re feeding poorly or are unusually fussy during feeds
• Their weight drops suddenly or dramatically

Often, growth slowdowns can be traced back to things like feeding difficulties, reflux, or mild digestive issues. In many cases, a few small adjustments — like tweaking feeding positions or checking for tongue-tie — can make a world of difference.

What “slow growth” doesn’t always mean

Hearing that your baby isn’t gaining weight quickly enough can be upsetting, but it doesn’t automatically mean there’s something wrong. Some babies are just naturally smaller or grow at a different pace.

You might hear the term “failure to thrive”, which sounds scarier than it is. It simply means a baby isn’t growing as expected and needs some extra support and attention. Many babies who are flagged for slow growth catch up naturally with time and go on to develop just as well as their peers.

In fact, research shows that:

• Babies who grow slowly in the first two months often catch up by age two.
• Those who grow more slowly between 2 months and 9 months might remain slightly lighter until school age, but typically catch up in height and weight by age 7.

How often should your baby be weighed?

To avoid unnecessary worry, it’s best to weigh your baby only as often as recommended:

• Up to 6 months: Once a month
• 6 to 12 months: Every two months
• Over 1 year: Every three months

If your baby is gaining well, alert, feeding comfortably, and reaching their milestones, there’s usually no need to weigh them more frequently. But if you’re feeling unsure, it’s absolutely fine to ask your health visitor for extra checks or reassurance.

Trusting your instincts

You’re the expert on your baby. If something doesn’t feel right — whether it’s about their growth, feeding, or general behaviour — don’t hesitate to speak up. Health visitors are there to help, not judge, and they’re used to all kinds of questions.

At the same time, try not to get too caught up in numbers. A baby’s growth and weight isn’t the only indicator of their wellbeing. If they’re full of energy, giving you those gummy grins, and engaging with the world around them, they’re likely doing just fine.