Find out the average baby weight for your child by using our baby weight chart.
Every baby is unique and each child's weight and length will differ, but there are some factors that can contribute to how much your baby weighs, such as genetics and the substance of their food which can depend on the mother's diet. If you yourself were a bigger baby, there's a chance your little one is more likely to be bigger too. And if you ensure you're eating plenty of nutrients, your breast milk will have all the ingredients to help your baby grow as big and strong as possible.
In a recent study in the Journal of Epidemiology (opens in new tab), researchers from the University of Bristol concluded that avoiding alcohol completely throughout pregnancy will also help babies to reach a healthy birth weight even before they are born.
The first thing babies do on their pattern of growth after birth is shrink. It takes a while for your newborn to get used to drinking milk rather than getting food through the placenta (and if you're breastfeeding (opens in new tab), for you to start making it), which means they can lose up to 10 per cent of their weight in the days following birth. (opens in new tab)
But by about 10 days old, your baby should start to put it on again.
What is the average weight of a newborn baby?
'The average weight for a baby at birth is around 7.5lbs, however, between 5.5 and 101bs is considered normal and healthy,' says Dr. Daniel Cichi, GP and medical advisor at Doctors 4 U (opens in new tab). 'First babies are normally lighter than their siblings which come later and boys are usually slightly heavier than girls.'
A study published in the journal, Nature Genetics found that a baby's genes can contribute to their birth weight. However, not all of these genes come from the mother, in fact, around one-quarter come from the baby's environment during pregnancy. For example, when the mother has higher blood sugar levels, the baby will naturally produce more insulin, causing it to grow. Too much blood sugar and insulin can cause your baby to put on extra weight as a result.
Average baby weight (opens in new tab) each month in the first year
- Birth is around 7.2lbs for a girl and 7.6lbs for a boy
- First month is 9.4lbs for a girl and 9.14lbs for a boy
- Second month is 11.5lbs for a girl and 12.4lbs for a boy
- Third month is 12.14lbs for a girl and 14.1 for a boy
- Fourth month is 14.3lbs for a girl and 15.7 for a boy
- Fifth month is 15.3lbs for a girl and 16.9lbs for a boy
- Sixth month is 16.1 for a girl and 17.8lbs for a boy
- Seventh month is 16.14lbs for a girl and 18.5lbs for a boy
- Eighth month is 17.8lbs for a girl and 18.15lbs for a boy
- Ninth month is 18.2lbs for a girl and 19.10lbs for a boy
- Tenth month is 18.11lbs for a girl and 10.3lbs for a boy
- Eleventh month is 19.4lbs for a girl and 20.12lbs for a boy
- Twelfth month is 19.12lbs for a girl and 21.4lbs for a boy
What is a centile chart?
Your health visitor will plot your baby's weight gain for the first few weeks (then less regularly as they grow up) in their health record on a baby weight chart (opens in new tab), also known as a centile chart.
Your centile chart shows lines that represent a zone within which your baby is expected to grow normally. If they're on the top line, or centile, it doesn't mean they're overweight. Equally, your little one isn't necessarily underweight if they're on the lower line. Either way, your baby is still within what's considered the normal range.
If your baby jumps up or down to the next centile, or begins to go beyond the zone altogether, speak to your health visitor. But it's not usually anything to be concerned about. Babies will often go through growth spurts, gaining nothing for a couple of weeks, then catching up in one go.
Some little ones may not follow the baby weight chart very well but this doesn't mean they're ill. Exclusively breastfed babies, premature babies or twins all show slightly different weight gain progress. In this case, your health visitor will use different, specialised charts to check your child is gaining weight properly.
This is an outline of what your baby should be weighing with a month by month guide, but for a more detailed overview, take a look at a centile chart that shows week by week measurements.
Baby girl growth chart
Birth: 5.5lbs to 10lbs 1 month: 6.6 to 14 3 months: 7.7 to 15 6 months: 11.6 to 22 9 months: 13 to 25 12 months: 14.3 to 27
Baby boy growth chart
Birth: 5.6lbs to 11.2lbs 1 month: 6.6 to 13.2 3 months: 9.9 to 18.7 6 months: 11.9 to 23 9 months: 14.3 to 26.2 12 months: 15.6 to 28.4
What’s the average baby length?
'The average length for a full-term baby at birth is 20 inches, however, between 18 and 22 inches is considered normal and healthy,' says Dr Cichi. According to the University of Michigan, your baby's head will grow at its fastest rate during the first 4 months after birth than at any other time. This increase is the result of rapid brain growth. The average head circumference at birth is roughly 13.5 in. (34.5 cm). By the end of the first month, it increases to roughly 15 in. (37.6 cm).
How often should my baby be weighed?
Your baby's weight will fluctuate the most in the first few weeks so it's normal to have them weighed after the first fortnight to check their weight is steadily increasing after taking an initial dip.
Your baby should then be weighed once a month for their first six months, there's no need to weigh them more than that. From being six to 12 months old your baby should be weighed no more than every other month. Once your little one has passed their first birthday they shouldn't need weighing more than once every three months.
Usually, your baby will gain weight most rapidly in the first six to nine months. Their rate of growth will gradually slow down as they become a toddler and are more active. If your baby or toddler is ill, their weight gain may slow down for a while. It will usually return to normal within two to three weeks. If you have any concerns that your baby is underweight or overweight your health visitor can look into this with you.
Is my baby putting on weight properly?
Your baby will rely on either breast or bottle to give them the nutrients that they need to keep them growing at the right pace. You can check if your baby is taking in all those nutrients properly by looking out for some of these signs. Here's a rough checklist that should show if they're getting enough nutrition in their milk:
- They have yellowy, seedy poo five times a day to begin with, slowing to an average of one a day from three months onwards
- Their nappy is wet and/or heavy. Hold a fresh one in the other hand and compare the weight of the two if you're unsure
- Their wee is clear. If it's yellow your baby could be dehydrated and not getting enough to drink
- A bottle has the advantage of giving an accurate measure of how much they've taken
- At the breast, your baby should be making gulping and swallowing noises
- They're happy after a feed and don't cry for more
- They're following the height and weight chart to the satisfaction of your doctor or health visitor
Remember, it's normal to go a few weeks where there's no gain, sometimes even a small weight loss, usually followed by a growth spurt
Rose Goodman joined Future Publishing in 2020 and writes across print titles and websites such as Woman&Home, GoodtoKnow and MyImperfectLife.
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