Is my baby the right weight?

If you’ve ever worried about your baby’s growth you’re not alone. We answer your most common weight worries and explain baby growth charts


“Mums are fixated with baby weight. The first thing most new parents ask after whether it’s a boy or a girl, is how much the baby weighs,” says Gail Johnson, education and professional development advisor with the Royal College of Midwives. How much a baby weighs is determined by genetics and can also be influenced by your health and nutrition during pregnancy. It’s not how heavy babies are at birth or in the following months that’s important though, it’s the rate at which they gain weight. Every child follows their own growth pattern from birth.


How much do babies usually weigh at birth?

As you would expect, babies vary a lot in weight at birth, with most ranging from about 2.5kg (5lb 8oz) to 4.5kg (9lb 14oz). The average British birth weight is 3.3kg (7lb 5oz).

Is it true babies often lose weight after birth?

Yes, one of the first things your baby might do in life is lose weight – up to around 10% of their original weight in the days following birth. But by about 10 days old, your baby should start to put it on again.

Who weighs my baby?

Your health visitor will plot your baby’s weight gain for the first few weeks (then less regularly as he grows up) in his health record on a growth chart, also known as a centile chart. Vicki Scott, baby feeding and wellbeing adviser, says, “Especially with your first baby, keeping a chart gives you a confidence boost that you’re doing things right. Making sure your baby is getting the right amount of food is important for brain development, future healthy growth and for settling the foundations for a healthy diet through her life. Plotting weight on a chart keeps a record for everyone’s peace of mind, and means that if a baby is gaining too much or too little weight then extra support and advice can be given if necessary.”

How do growth charts work?

The charts plot babies’ weight against height on lines called centiles. These are numbered points out of 100 – think percentages. If your child’s on the 25th centile, that means in a group of 100 children, 24 would be lighter and 75 heavier.

The lines represent a zone within which your baby is expected to grow normally. If she’s on the top line, or centile, it doesn’t mean she’s overweight. Equally, she’s not underweight if she’s on the lower line. Either way, she’s still within what’s considered the normal range.

How much weight should my baby gain?

In the early weeks an average-size baby should gain an average of six to eight ounces (175g to 225g) a week. And by six months should have doubled her weight. She’ll also have spurts and slower periods of growth, so don’t panic if you find she’s put on more weight one week and less the next. “A baby’s weight may dip after birth but from two weeks you ideally want her weight back to where she started from,” says Gail. “There’ll be blips – like when she’s teething or moving on to solids.” Your health visitor will advise you if she thinks you should move on in your feeding regime.

Your health visitor will help you keep track of your baby’s weight gain

How will my premature baby’s weight differ to other babies?

A premature baby might not put on weight at the same rate as a full-term baby for as long as two years. The new style charts have graphs for premature babies, whereas the old charts compared premature babies on the same scale as full-term babies. “Having their own chart means premature babies, or those at a low birth weight, won’t be compared to ‘Mr or Miss average’ anymore,” says Vicki Scott.

My baby was heavy at birth, what about her weight gain?

Of course your baby’s weight is likely to be heavier than average as she grows if she starts off heavier. But as long as the weight gain is at a healthy rate, your health visitor won’t be worried. “Once you plot the baby’s weight on the chart, it puts her on a certain centile and you would expect her weight to follow that pattern,” says Gail. Your health visitor will still keep an eye on her weight if it increases too rapidly, whether she was heavy at birth or not.

I had twins – should they gain weight at the same rate?

No. Each baby will have his or her own chart, and be treated as individuals growing at their own pace. “Twins are usually born at different weights, so it follows that their charts will be individual,” says Vicki. “As a mum you’ll soon learn each twin’s temperament, appetite and feeding routine.”


My baby’s gaining weight slowly, should I be worried?

“As long as her weight is within the weight line she started on, your baby is gaining weight at an acceptable rate,” says Gail. “If her weight dips below two centiles from her average that might raise some concerns for your health visitor. You’ll be asked about how your baby is feeding and how she is in general, such as how alert, how her nappies are and if anything’s changed.” Your health visitor may discuss whether you should consider weaning or looking at your feeding times to increase your baby’s food intake if she’s concerned.


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