Baby weight

What’s the ‘right weight’ for a baby?

Just like adults, babies come in all shapes and sizes! The average British birth weight is 3.3kg (7lb 5oz), and most newborns weigh between 2.5kg (5lb 8oz) and 4.5kg (9lb 14oz).

How much your baby weighs is determined by genetics and your health and nutrition through pregnancy. But it’s not how much your baby weighs at birth that’s most important – it’s the rate at which they gain weight afterwards.

Losing weight after birth

Every child follows a growth pattern from birth. And usually the first thing they do is lose weight! This is because it can take a while for them to get used to drinking milk. And if you’re breastfeeding, your body has also got to get used to producing milk too. Many babies lose up to 10% of their weight in the first few days after birth. But by about 10 days old they should have started to put it on again.

Measuring your baby's growth

Your baby’s growth is measured on a centile chart. Whether big or small, they’re expected to put on weight at a steady pace, staying in the same range on the chart. Just because your baby may be at the top or bottom end of the chart doesn’t mean they are over or underweight.

Make sure you attend your baby clinic regularly. Your baby’s growth and health will be carefully monitored and your health visitor can answer any questions or concerns you may have.

How much weight should my baby gain?

In the first few weeks your baby will probably gain about 175g to 225g (6oz to 8oz) a week. By about six months they will probably have doubled their birth weight and after this their weight gain will gradually slow down.

The centile charts used to measure growth are just guidelines. So while your baby’s weight should normally stay in their range, don’t be worried if they have the occasional blip. These may be caused by growth spurts, illness, difficulty adjusting to solids or simply burning up more calories as they start to crawl. If you have any concerns about your baby’s growth, speak to your health visitor.