How your baby gains weight

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

Babies are usually weighed at these times (although some babies will need more frequent checks):

• at birth
• during their first 2 weeks
• once a month up to 6 months
• every 2 months from 6 to 12 months
• every 3 months after their first birthday

Your baby's birth weight will depend on how close they were born to their due date. Babies born before their due dates are often small, 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
• gender — 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 triplet — babies of multiple births are often smaller
• your and your partner's height and weight

If your baby is born significantly smaller or larger than average, they may be monitored more closely to check for possible problems.

From birth, your baby needs breast milk or infant formula to have the right nutrition and good weight gain. It is normal for breastfed babies to receive small amounts of colostrum (early breastmilk) in their first few days. Mature breastmilk then provides all the nutrients they need to help them grow.

It is normal for babies to lose some weight after they are born. Healthy babies can lose up to 10% of their birth weight in the first week after being born, and return to their birth weight after 2 to 3 weeks with regular feeding.

Many factors can affect your baby's weight gain. Some babies might not take in enough nutrients due to difficulties with:

• breast feeding
• formula preparation
• a structural problem, such as a cleft palate

Other babies may not gain enough weight because of problems the parents may experience, such as poverty, mental illness or social difficulties.

Some babies have difficulty absorbing food, for example, those with an allergy to cow's milk. Others may need more calories than other babies of a similar age and weight because of a chronic illness such as congenital heart disease.

All babies grow differently, but there are guidelines for healthy weight gain.

A useful guide is that most healthy, full-term newborn babies double their birth weight by 4 months.

Male babies' weight will triple in about 13 months. Female babies' weight will triple in about 15 months. However, all babies grow at their own pace.

Infant growth between the ages of 0 and 2 years is usually calculated using the World Health Organization's (WHO) growth standards. Infant growth charts allow health professionals to compare your baby's growth with that of all other babies of the same age and sex.

Growth milestones are adjusted for premature babies. Premature babies' growth is considered based on their corrected age rather than their chronological (birth) age.

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

Your baby's weight and other measurements will be recorded in your baby's health record, by your healthcare practitioner.

This record helps health professionals check your baby's growth and development against babies of the same age and sex.

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

Read about your baby's developmental milestones.

Your baby's weight gain might slow down because:

• your baby starts to sleep more and feeds less often
• you or your baby become ill
• your breastmilk 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 about seeing a lactation consultant.

If your baby is having feeding difficulties or isn't gaining weight at the expected rate, you should see your doctor.

Learn more about weight gain in breastfed babies from the Australian Breastfeeding Association.

Find a lactation consultant near you on the Lactation Consultants of Australia and New Zealand website.