How Much Weight Should a Newborn Gain Each Week? When Babies Regain Birth Weight

How much weight should a newborn gain per week? About 150 to 200 g a week up to 3 months, once back to birth weight at about 2 weeks. Tresillian and Children's Health Queensland both give that figure. Gains then slow to 100 to 150 g a week to 6 months, then 70 to 90 g to 12 months.

Before that, a loss is expected. Most newborns lose up to 10% of their birth weight in the first week, then climb back. One weigh-in rarely settles the question, because weekly gains vary. The Australian Breastfeeding Association says a month's average is often more helpful.

This guide puts the Australian figures beside the World Health Organization's growth data, works through a 4-week average, and lists the signs that need a call to your child health nurse or GP.

How much weight should a newborn gain each week?

From about 2 weeks to 3 months, the Australian guide is 150 to 200 g a week. Tresillian gives that figure for birth to 3 months, and Children's Health Queensland gives 150 to 200 g each week in the first 12 weeks. The guide steps down as babies get older.

The WHO figures are supporting evidence. The first is the net gain over the first 4 weeks: about 880 g for girls and 1,020 g for boys. The second is about 215 to 255 g a week from 4 weeks to 2 months, then 165 to 185 g a week to 3 months.

The Australian column comes from Tresillian(opens in a new window), which lists the three weekly bands as an expected guide. Tresillian calls the growth chart the preferred measure, so the grams are a rough check beside the chart. Children's Health Queensland(opens in a new window) lists the same 150 to 200 g as one sign a breastfed baby is getting enough milk.

The WHO column is our conversion of the WHO weight velocity standards(opens in a new window) into grams a week. WHO publishes how much healthy babies gain in each month. We took the middle figure (the 50th percentile) for girls and boys and divided by the weeks in that month. It is supporting evidence from outside Australia.

Two things stand out when the columns sit side by side:

• The second month runs fast. The WHO middle figure from 4 weeks to 2 months works out above 200 g a week. A baby gaining 250 g a week at 6 weeks is not unusual.
• The healthy spread is wide. From 2 to 3 months, the middle 70% of girls in the WHO data gained between about 490 g and 950 g in the month. For boys it was about 580 g to 1,070 g.

How much weight do newborns lose after birth?

Most newborns lose some weight in the first days, and a loss of up to 10% of birth weight in the first week is what Australian health services describe as normal. Pregnancy, Birth and Baby(opens in a new window), the Australian Breastfeeding Association(opens in a new window) (ABA) and Tresillian all give that 10% figure.

The ABA says this early loss is normal: a breastfed newborn only needs small amounts of colostrum, the first milk, and milk supply increases quickly around day 3 or 4. Pregnancy, Birth and Baby says the loss usually lasts up to day 5 to 7. Children's Health Queensland says babies start to regain weight by days 4 to 6.

Is an 8% weight loss normal for a newborn?

A loss of 8% at day 3 sits inside the up-to-10% range that Australian guidance calls normal. To work out the percentage, take today's weight from the birth weight, divide by the birth weight and multiply by 100. A baby born at 3,400 g who weighs 3,130 g on day 3 has lost 270 g, which is 7.9%.

This table shows where the 10% line falls for common birth weights:

The percentage is only half the answer. The ABA compares two babies at a 10% loss. A 2 day old who has lost 10% and is sleepy and not feeding well will need extra support. A baby who has lost 10% but is feeding often may not.

When do babies regain birth weight?

Most babies are back to their birth weight by 10 to 14 days, and some take 2 to 3 weeks. Pregnancy, Birth and Baby gives both figures on the same page: most return by around 10 to 14 days, and babies often return to birth weight by 2 to 3 weeks with regular feeding.

The other Australian sources land on 2 weeks. The ABA says breastfed babies typically regain their birth weight by 2 weeks. Children's Health Queensland says babies should reach their birth weight by 14 days. Tresillian says a nurse or doctor will investigate further if a baby hasn't regained it by around two weeks.

Read together, 2 weeks is the usual mark. A baby who isn't back by then is one your midwife or child health nurse will want to weigh again, with a closer look at feeding.

That is why the early weigh-ins cluster here. Pregnancy, Birth and Baby lists checks often around 5 days and 10 days of age, to check feeding and early weight changes.

What happens at those early visits is in our guide to baby health checks in Australia. The rest of week 2 is covered in newborn development week by week.

Weight gain by age: 0 to 3, 3 to 6 and 6 to 12 months

Babies gain fastest in the first 3 months, then more slowly each few months after. Tresillian's weekly guide drops from 150 to 200 g, to 100 to 150 g, to 70 to 90 g across the first year.

0 to 3 months: about 150 to 200 g a week, once birth weight is regained. This is the fastest growth of the first year. The ABA says breastfed babies usually gain a bit faster than formula-fed babies over these 3 months.

3 to 6 months: about 100 to 150 g a week. The ABA says breastfed babies grow more slowly after the first 3 to 4 months. It adds that there's probably no need to worry if a 4 month old is no longer gaining as quickly as before.

Most healthy, full-term babies double their birth weight by about 4 months, says Pregnancy, Birth and Baby. Tresillian gives 4 to 6 months.

6 to 12 months: about 70 to 90 g a week. Pregnancy, Birth and Baby says most babies triple their birth weight by 13 to 15 months. Tresillian says birth weight often triples by 12 months, and length grows by about 1.5 times in the first year.

A week of 80 g can sit inside a month that averages 170 g a week. The month is the number to read.

Why weekly weigh-ins bounce (look at the monthly average)

A single week's gain can land well above or below the guide while the month sits right on it. The ABA says weight gains vary from week to week, and looking at the average gain over a month is often more helpful.

Children's Health Queensland says a judgement on growth is best made after a series of measurements.

Some of the bounce comes from the weighing itself:

• Different scales. Children's Health Queensland suggests the same baby scales where possible.
• Clothes and nappy. Weigh without clothes or a nappy, says Children's Health Queensland. Tresillian says nurses weigh babies undressed on digital baby scales for a consistent measurement.
• A feed. A weigh-in straight after a feed reads higher than one before it, so note the time of the last feed.
• Short-term dips. Tresillian lists a cold, weaning or starting a new childcare arrangement as reasons weight can stall or dip for a while.

A worked 4-week average

Here is a made-up example baby, born at 3,400 g:

The day 5 weight is 7.1% below birth weight.

Taken alone, the 80 g week at 4 weeks sits under the guide and the 250 g week sits above it. Across the 4 weeks from 2 to 6 weeks, this baby gained 680 g. That averages 170 g a week, inside the 150 to 200 g guide.

That is the sum to do after a weigh-in that worries you. Take the latest weight, subtract the weight from about 4 weeks earlier, and divide by the weeks between them.

The same run of weights goes on the growth chart in your baby's health record, where the line shows how your baby is tracking against other babies. How to read that chart is in our guide to baby growth charts and percentiles.

The nurse also measures head size at most early checks. A head percentile follows its own rules, set out in what a head circumference percentile means.

Do breastfed and formula-fed babies gain differently?

Yes, a little. The ABA says breastfed babies usually gain a bit faster than formula-fed babies in the first 3 months, then more slowly from 3 to 4 months onwards. Healthy breastfed babies usually weigh less than formula-fed babies at one year.

The charts in your baby's health record allow for that. The ABA notes that the WHO growth charts are based on the length and weight of healthy breastfed babies. Pregnancy, Birth and Baby says the WHO charts are used in Australia from birth to 2 years.

Pregnancy, Birth and Baby lists three common reasons weight gain slows: a baby starts sleeping more and feeding less often, you or your baby become ill, or your breast milk supply changes.

The other signs a baby is getting enough, such as wet nappies and settled spells, are in our guide to how much milk a baby drinks. For bottle-fed babies, see the signs of enough in the formula guide.

If your nurse asks you to keep a record of feeds before the next weigh-in, our guide to keeping a baby feeding diary covers what to write down.

When to talk to your nurse or GP about weight gain

Slow gain doesn't always mean something is wrong. Pregnancy, Birth and Baby says some babies are smaller because of their genetics. The ABA says to consider your baby's length, head circumference and overall health alongside the weight.

Some signs need a professional's eyes, and a few can't wait.

The wet nappy counts to expect each day are in our guide to how many wet nappies a day.

For advice any time, the ABA's Breastfeeding Helpline(opens in a new window) on 1800 686 268 runs 24 hours. The Pregnancy, Birth and Baby(opens in a new window) helpline on 1800 882 436 connects you to a maternal child health nurse from 7am to midnight (AET), 7 days a week.

Keeping the weigh-ins in one place

The 4-week sum needs every weight in one place. Clinic weights go in the health record book, while a pharmacy weigh-in or a note from the midwife's visit can end up on a scrap of paper. A page in the back of the health record works, as long as every weight goes on it.

BabyLog's free growth log plots every weight, length and head measurement you enter on WHO-standard growth charts, with full history on the free plan. It shows the line and leaves the judgement to your nurse.

Before a check, a Pro Checkup Report puts every weigh-in on one chart with the recent gain in grams a week, shared with your nurse as a private link or PDF.

If that would help between visits, you can start free in the browser on your phone.

Common questions