Baby weight

Baby weight

Understanding infant weight gain and weight loss

Newborn baby weight can vary greatly; it can depend on your own health and nutrition during pregnancy, as well as their inbuilt genetic make-up, which comes from both parents. Learn what’s considered normal and why your baby’s weight gain in their first weeks and months is an important indicator of their development and wellbeing.

Baby weight and growth

Babies come in all shapes and sizes, just like their parents. Your own health during pregnancy, as well as the physical build of build of both you and your partner, are some of the factors that will affect your baby’s birth weight.

Newborn weight loss

All babies lose weight after they are born, with many losing 7-10% of their birth weight in the first few days.

Once breastfeeding is established and your baby is latching on well and feeding regularly, they should start gaining weight again. Babies generally get back up to their original birth weight within 10–14 days after birth.

How your baby’s growth is measured

Your baby’s weight will be carefully monitored during the first couple of months to make sure they are developing healthily. This is why it’s important to keep up with your baby's clinic appointments.

However much your baby weighs, it’s their growth between appointments that your healthcare professional will be looking for.

Baby growth is measured using a centile chart. This is a guide to your baby’s individual weight gain, rather than a way to compare babies against each other.

Don’t be too concerned if your baby starts off at the top or the bottom end of the baby weight chart – this doesn’t mean they are over- or underweight. What your health visitor will look for is a steady rate of weight gain, along a given line (centile) on the growth chart.

What is a healthy rate of baby growth?

The growth centiles show the average weight gain for babies of different ages, with the most rapid growth happening in the early months.

By the time they are 6 months old, they are likely to weigh twice as much as they did at birth. Your baby's growth will then gradually slow down.

Your baby may gain less weight when they’re ill or teething, due to loss of appetite.

Occasionally, your baby’s weight may increase or decrease at a higher rate than normal, caused by sudden growth spurts or bouts of illness. Your baby's weight can also fluctuate around the start of weaning, when they may have difficulty accepting solids, or when they become more mobile and their activity levels increase.

A general trend of good weight gain is a sign that your baby is growing well and meeting their early milestones for a lifetime of healthy development. If you have any concerns about your baby's weight gain, talk to your GP or public health nurse.

Important notice

Breastfeeding is best for babies and provides many benefits. It is important that, in preparation for and during breastfeeding, you eat a varied, balanced diet. Combined breast and bottle feeding in the first weeks of life may reduce the supply of your own breastmilk, and reversing the decision not to breastfeed is difficult. Always consult your healthcare professional for advice about feeding your baby.