How your baby gains weight

Your baby's weight is measured regularly at their health checks using a special baby scale. Your healthcare provider will also measure their length and the size of their head (head circumference). Regular checks help you and your health team know that your baby is healthy and growing well.

Babies are checked closely, especially in the first month, to support healthy growth and feeding. Your doctor or nurse will weigh your baby regularly, usually at these times (some babies may need checks more often)

• At birth — in hospital or birthing centre.
• In the first 2 weeks — often around 5 days and 10 days of age to check feeding and early weight changes.
• Once a month up to 6 months — to regularly track growth.
• Every 2 months from 6 to 12 months — to keep checking growth.
• Every 3 months after their first birthday — ongoing checks as your child grows.

Your baby’s birth weight will depend on many things. One important factor is how close your baby is to their due date. Babies born early are often smaller, while babies born after their due date are often larger.

Your baby's birth weight can also be affected by:

• birth order — first babies can be smaller than future siblings
• sex — male babies are often larger
• your general health, and any pregnancy complications
• your health and diet before and after birth
• if your baby is a twin or other multiple
• your height and weight, as well as partner's

If your baby is smaller or larger than average at birth, your healthcare team may monitor them a bit more closely to support their health and development.

From birth, your baby needs breast milk or infant formula to grow well and gain weight. In the first few days, breastfed babies get small amounts of colostrum (early breast milk). After this, your breast milk changes and continues to provide all the nutrients your baby needs.

It is common for babies to lose some weight after birth. Healthy babies can lose up to 10% of their birth weight in the first week. With regular feeding, they often return to their birth weight by 2 to 3 weeks of age.

Many things can affect a baby's weight gain. 

Some babies may not get enough nutrients because of difficulties, such as:

• breastfeeding challenges
• problems with preparing formula
• a structural condition, such as a cleft palate

Sometimes, a baby’s weight gain can also be affected by family or social challenges, such as financial stress or mental health concerns.

Some babies may have trouble absorbing nutrients, for example, if they have an allergy to cow's milk. Others may need more calories than babies of a similar age because of a health condition.

All babies grow at their own pace, but there are general patterns for healthy weight gain.

Most healthy, full-term babies double their birth weight by about 4 months. They usually triple their birth weight by around 13 to 15 months.

Doctors and nurses use growth charts to track your baby’s growth. These charts compare your baby’s weight with other babies of the same age and sex.

If your baby was born early, their growth is measured using their corrected age (based on their due date), rather than their birth age.

How do I know if my baby’s weight gain is healthy?

What to look out for:

• It is normal for babies to lose some weight in the first few days after birth, usually up to 5 to 7 days. Most babies return to their birth weight by around 10 to 14 days. 
• If your baby loses more weight than expected, or is not gaining weight over the first few weeks, speak with your healthcare provider.

Weighing your baby regularly helps you know if they are healthy and growing well.

Your doctor or child health nurse will record your baby's weight and other measurements in your baby's health record. This is a book that records important information about your baby's health.

Your baby's weight and length are plotted on a graph that shows weights and lengths for babies at different ages. This shows how your baby is growing between check-ups.

Read about understanding baby growth charts.

Your baby's weight gain might slow down if:

• your baby starts to sleep more and feeds less often
• you or your baby becomes ill
• your breast milk supply changes (there are different reasons this might happen)

If you're worried, see your doctor, nurse or midwife or call Pregnancy, Birth and Baby on 1800 882 436.

For extra help with breastfeeding, ask your doctor or child health nurse, or visit a lactation consultant.

To find a lactation consultant or maternal and child health service near you, use the Pregnancy Birth and Baby Service Finder (Opens in new tab) tool.

If your baby is having feeding difficulties or is not gaining weight as expected, speak with your doctor or child health nurse.

You can also seek advice if you are worried about your baby’s feeding, growth or general health. Early support can help identify any issues and make sure your baby is getting the care they need.

The Australian Breastfeeding Association has more information about breastfeeding.
Find a lactation consultant (Opens in new tab) near you.

Read about breastfeeding (Opens in new tab) on The Royal Women’s Hospital website. 

Languages other than English

The NSW Government’s Multicultural Health Communication Service has translated their breastfeeding tips for new mothers (Opens in new tab) into many community languages. 

The Multicultural Centre for Women’s Health (Opens in new tab) has health resources in other languages, including pregnancy and infant feeding information.

Information for Aboriginal and/or Torres Strait Islander peoples

The Australian Breastfeeding Association has a collection of breastfeeding resources (Opens in new tab) for Aboriginal and/or Torres Strait Islander families. 

Breastmilk Talk ‘Ngaminjang Djama (Opens in new tab)’ is a video resource where Aboriginal and/or Torres Strait Islander people talk about breastfeeding.