Understand your baby’s weight

Don’t let worry about your baby’s size get you down. Get the low down from our guide...


It’s one of the first bits of information you’re given after the birth, so no wonder your baby’s weight is on your mind from day one. But you shouldn’t worry about it.


“As little ones grow it’s not how heavy they are at any given time that’s important, but the rate at which they gain weight,” says Sam Saunders, community nursery nurse at Watford General Hospital and maternity nurse for The BabyWorks. “And every child will usually follow a set pattern of growth from birth.”

There are fears that in the past parents of breastfed babies have been wrongly told their babies need to gain weight.

Does big mum mean big baby?

It’s not a given that a larger mum will have a big baby and a smaller mum will have a little one. “There appears to be some genetic factor at play though,” says Joy Horner, independent midwife (www.birthjoy.co.uk). “Often if a mum has a big baby, it follows that her daughter will have a big baby too.”

Nutrition in pregnancy plays a part too – the general rule of thumb is that if you have a healthy and balanced diet then it’s likely your baby will be born a healthy weight. “But sometimes a mum who has a poor diet will still have an average-sized baby as he’ll get the nutrients he needs from her no matter what,” adds Joy.

The first thing you’ll ask once you know the sex of your baby, is how much does she weigh?

What’s normal to start with?

To begin with you may notice your baby’s weight drop, but don’t panic as this is completely natural. “It takes a while for a newborn to get used to drinking milk rather than getting food through the placenta,” says Joy. Which means he can lose up to 15% of his birth weight in the days following birth, but ideally at two weeks you want his weight back to where he started from.

Once things have settled down, an average-sized baby should gain between half an ounce and an ounce per day, and by six weeks, should have doubled his weight. “But it isn’t an exact science as he may have spurts or slower periods of growth, which is normal, and it’s OK if he puts on more weight one week and less the next,” adds Joy.

Be prepared for blips, too, as weight may fluctuate when your baby starts getting active, during teething or when he’s being moved onto solids.

The first thing you’ll ask once you know the sex of your baby, is how much does she weigh?

When does the weighing happen?

“Your baby is weighed at birth, and normally, again at five days and 10 days by your midwife,” says Sam. “Your health visitor then usually takes over and will weigh again at 14 days and from then on it’ll be every fortnight up to six months, and every month up to a year, but these times may vary slightly from clinic to clinic.”

The results from his weigh-ins are plotted on a growth chart in his health record book.

You might be thinking ‘Why all the fuss? Why can’t I just weigh my baby on scales at home?’ “That’s not really such a good idea,” advises Sam. “This is because the scales you have at home aren’t regularly serviced like they are in clinics, so you can’t be sure they’re accurate, plus it needs to be done by a trained health professional.”

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Will my big baby stay big?

“If your baby was born big he’s likely to be heavier than average just because he’s started off heavier, but as long as his weight gain is at a healthy rate your health visitor won’t be worried,” says Sam.

“If he moves out of his centile to become heavier, your health visitor will ask how often and how much your baby is feeding, how many wet and dirty nappies he has and whether he’s settling and sleeping well.”

If that’s all normal she’ll generally then refer him to a GP, who may organise for him to see a paediatrician who’ll look into slowing his weight gain down as opposed to getting him to lose excess pounds.

Combining bottlefeeding with breastfeeding means you can get the benefits of both for you and your baby.

What happens when a baby is underweight?

“As long as his weight remains within the weight line he started on, your baby is gaining weight at an acceptable rate,” says Sam.

“But if his weight drops below the centile he started on, your health visitor will do the same checks as if he was overweight and then decide whether or not it’s necessary to refer him to a GP.”

Premature babies are usually born underweight and might not put on weight at the same rate as a full-term baby for as long as two years. “But the new-style charts have graphs for premature babies so they won’t be compared to full-term babies,” says Joy.

Prem babies normally have scheduled feeding, calculated by their weight, rather than being fed on demand. This is because they often won’t wake up to feed. Managing their feeds like this also means health professionals can monitor their food intake more carefully. “Some premature babies may be given a special premature baby milk to help them gain weight,” says Sam.

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Are twins treated the same?

Twins are usually born at different weights and have different appetites, so are treated differently. “Each will have his own weight chart and grow at his own pace,” says Joy.

The symptoms of your baby’s food allergies and intolerances can be hard to spot.

How much food does my baby need?

Babies of six months old or less who aren’t yet on solids generally need around 2.5 to 2.7oz of milk per pound of body weight. But don’t worry about monitoring it too closely, says Sam. “If you’re breastfeeding, do it on demand. Respond to his needs and feed him when he’s hungry,” she says. “As long as your baby isn’t poorly he should know how much he needs.” This applies to bottle-fed babies too.

From six months on, offer starchy foods such as potatoes, yams, rice or bread, and fruit, vegetables and meat or lentils, as these are all part of a healthy balanced diet and should help to keep his weight healthy.

Once your baby is eating plenty of solids several times a day, the Department of Health advises you to drop a milk feed but continue to breastfeed or give 500-600ml of infant formula a day until he is at least a year old.

Whether you use expressed breast milk or infant formula, bottlefeeding can mean Dad gets to share feeding duties.

Your growth chart explained

  • The charts plot a baby’s weight against height on lines called centiles.
  • The lines represent a zone, or range of measurements, within which your baby is expected to grow normally.
  • If he’s on the top line, or centile, it doesn’t mean he’s overweight. And he’s not underweight if he’s on the lower line.
  • Regardless of which centile he’s on, as long as he continues to follow it roughly then he’s gaining weight as he should be.
  • “Keeping a chart gives mums the confidence that they’re doing things right, and it makes it easy for health visitors to spot whether a baby is gaining too much or not enough weight,” explains Sam Saunders, community nursery nurse at Watford General Hospital.
  • “The growth charts are based on measurements from exclusively breastfed babies so mums who bottle feed may find their baby is heavier than average,” adds Sam.
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Mums’ stories

“My prem baby is now thriving”

“Jacob was born at 34 weeks weighing 6lb 4ozs and was fed through a tube, as well as breastfed and given a supplemented infant formula to help him gain weight. I was advised to wake him for feeds every two hours at first, and gradually he gained weight. My advice to other mums with prem babies is to keep going. Early babies take longer to catch up but usually get there in the end. Jacob’s 2 now and though he’s still slightly small for his age, he’s absolutely fine.”

Kate Fever, from Devon, mum to Gemma, 4, and Jacob, 2

“My baby put on too much weight”

“Deshoney weighed 8lb 4oz at birth and put on weight very quickly – she liked her milk so much! I started to worry she was gaining too much, so my health visitor told me to keep a diary of how much she was drinking and to give her water sometimes instead of milk. By keeping track of how much she was taking and occasionally swapping milk for water, under direction from the health visitor, she gradually lost weight healthily. All my children have followed a similar pattern but they’re now all the right weight.”

Bontle Mmereki, 20, from Northampton, mum to Deonte, 3, Donell, 2, and Deshoney, 6 months

“My son was a big, hungry baby”

“Joshua was 10 days early and weighed 8lbs 11oz. I was worried he’d be very overweight due to his birth weight and the fact he went on to drinking hungry baby milk (more filling milk) very early. He also had to be weaned at 4 months as he was so ravenous! But, as he was gaining weight at a steady rate and following his centile lines, I was reassured. Though he’s big for his age and taller than his peers he isn’t overweight and is perfectly healthy.”

Sonia Prater, 28, from Devon, mum to Joshua, 2


Did you know…

The average birth weight for a full-term baby is normally between 7lb 7oz and 8lb 8oz.

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