Taking the worry out of having your breastfed baby weighed
Most babies will be measured and weighed many times over the first few years of life. These checks can help you to know if your baby is healthy and growing well.
Patterns of weight gain and growth for breastfed babies
All babies are different, but breastfed babies typically:
- lose up to 10% of their birth weight in the first week
- regain their birthweight by 2 weeks
- grow more slowly after the first 3 to 4 months
- double their birthweight by 4 months..
Weight gains can vary from week to week. It‘s often more helpful to look at average weight gain over a month. Also consider your baby's length, head circumference and overall health. Sometimes a baby may have a low weight gain but may have grown a lot in length.
These are just general guidelines. The ‘Commonly asked questions’ at the end of this page contain extra information. Speak to your doctor or child health nurse if you are concerned about your baby's growth.
Weight gain slows over time
After the first few months, you may notice your baby gains weight more slowly. This is normal. Here are some important things to know about how breastfed babies grow:
- In the first 3 months, breastfed babies usually gain weight slightly faster than formula-fed babies.
- From 3 to 4 months onwards, their weight gain slows down compared to babies who are fed formula. This means there’s probably no need to worry if your 4-month-old baby is no longer gaining weight as quickly as they once did.
- Healthy breastfed babies usually weigh less than formula fed babies at one year.
A note about growth charts
World Health Organization (WHO) growth charts are based on the length and weight of healthy breastfed babies. You can find these charts in your baby health record book. These charts show how your baby grows compared with other babies. Other growth charts may be less useful.
When you’re looking at the growth charts, remember that the 50th percentile on the chart is an average, not a ‘pass’ mark or something to aim for or beat. It simply means that 50% of babies will be below that line and 50% above.
Commonly asked questions about weight gains
If you are worried that your baby isn't gaining enough weight, you're probably also worried about your milk supply. There are some reliable signs that your baby is getting enough.
You may be making lots of milk, but baby isn’t able to remove the milk from your breasts very well. This can cause your supply to drop over time. If you’re concerned that your baby isn't getting enough milk, ask for extra breastfeeding support. An ABA breastfeeding counsellor, child health nurse or lactation consultant can help you to check if baby is feeding well, and give you tips to increase your supply if needed.
This isn’t always a sign of a problem. The WHO child growth charts show that weight gains of breastfed babies usually slow down around 3 to 4 months.
If you're worried about your baby's weight you could offer a couple of extra breastfeeds a day while you seek support from your child health nurse.
Here are some other possible causes to think about.
- Is your baby feeding often enough? In the first few months, most babies need at least 8 to 14 feeds in 24 hours.
- Have you been offering only one breast per feed? Some babies start off just needing one breast but may need both as they get older. You could try offering your baby the second breast at each feed.
- Has your baby been having fewer feeds recently, perhaps because they are sleeping longer at night? An extra feed during the day may help.
- Have you been trying to feed at set times instead of when your baby wants to? They may not be taking as much breastmilk as they were before.
- Is your baby feeding well? Some babies have a poor sucking action, so they don't remove milk from the breast well.
- Have you been stressed or unwell? Started a new medication? Noticed hormonal changes? For some mums these can cause a short-term dip in supply.
If your baby is underweight but has a good nappy count, there may be an underlying medical condition which is causing slow weight gain. Most health problems that cause slow weight gain can be treated and breastfeeding can continue.
infection (anything from a cold to a urinary infection)
vomiting or frequent posseting can mean a baby does not keep down enough milk to grow
a severe allergy to foods in the mother's diet could be a cause of low weight gain.
Test weighing involves weighing the baby before and after a feed, to work out how much milk they drank. Test weighing isn’t helpful unless it is done at every feed for 24 hours. Weighing after just one feed won’t tell you anything about your supply or how much milk your baby needs across a full day. Counting wet and dirty nappies is often an easier way to know if your milk supply is enough for your baby.
In the first 3 days babies may lose weight no matter how they're fed.
Babies only need small amounts of the first milk (colostrum) in the first few days. If you breastfeed your baby often from birth they will receive all the colostrum they need. Around day 3 or 4 your milk supply will increase rapidly. This is sometimes called your milk 'coming in'.
As your breastmilk supply increases, your baby’s weight will begin to increase too. They should regain their birthweight by about 2 weeks of age.
If your baby has lost some weight, it’s important to look at the whole picture of how your baby is doing. For example, if a 2-day-old baby has lost 10% of their birthweight and is sleepy and not feeding well, they will need a lot of support. A baby who has lost 10% but is feeding often, may not.
If you are concerned, speak to a health professional. It's okay to seek a second opinion if you're still unsure.
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© Australian Breastfeeding Association September 2024
