Newborn Weight Loss: What's Normal?
The midwife weighs your baby on day two and the number is lower than at birth. Don't worry — this is normal, and the scale is not wrong.
Here's why it happens, how much is typical, and when the number going down becomes something worth flagging.
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Why Newborns Lose Weight After Birth
Newborns are born with extra fluid — in their tissues, their gut, and their circulation — that they shed in the first few days of life (Flaherman et al., Pediatrics, 2015). This is not a feeding failure. It is what happens to every healthy newborn, regardless of how well they are fed.
In the first 48–72 hours, breastfed babies are also taking in colostrum, which is produced in small volumes by design. Their stomach capacity at birth is very small. The combination of normal fluid loss and low initial milk volume means the number going down in the first days is the only way it goes.
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How Much Weight Loss Is Normal
For breastfed babies, a loss of up to 10% of birth weight is generally within the normal range. According to Sundhedsstyrelsen (SST), typical weight loss is in the region of 7–10% (SST, Amning — en håndbog for sundhedspersonale). Formula-fed babies tend to lose less — typically 2–5% — because formula is available in consistent volumes from the first feed.
The lowest point — the weight nadir — is usually reached around days 2–3 (Flaherman et al., Pediatrics, 2015). After that, if feeding is going well, the baby starts to gain.
Babies born by caesarean section tend to lose slightly more weight than those born vaginally — a median of around 8–9% by 72 hours is common — because they retain more fluid during delivery and shed it more quickly afterward (Flaherman et al., Pediatrics, 2015).
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When Should They Regain Their Birth Weight?
Most babies regain their birth weight by around two weeks of age (SST, Amning — en håndbog for sundhedspersonale). SST recommends your midwife track weight in the days following birth to confirm the baby is on course. If birth weight has not been regained by three weeks, further assessment is warranted (National Guideline Alliance, NICE, 2017).
Once birth weight is regained, the expected gain is roughly 250g per week in the first two months (SST, Ernæring til spædbørn og småbørn). This is the number your health visitor will track at check-ups. It is an average — some babies gain more, some less — but consistent weekly gain matters more than any single weigh-in.
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When to Be Concerned
A loss of more than 10% of birth weight is the point at which clinical assessment is recommended (National Guideline Alliance, NICE, 2017). This does not automatically mean something is wrong, but it does mean a closer look at feeding is needed.
Other signs that warrant a call to your midwife or health visitor:
- Fewer than 6–8 wet nappies per day from around day 5 (SST, Amning — en håndbog for sundhedspersonale)
- Persistent jaundice alongside poor weight gain — weight loss and jaundice are linked, as poor intake slows the baby's ability to clear bilirubin (SST, Gulsot hos spædbørn)
- A baby who is consistently hard to rouse for feeds, or who falls asleep repeatedly before finishing (SST, Amning — en håndbog for sundhedspersonale)
- Birth weight not regained by three weeks (National Guideline Alliance, NICE, 2017)
If you're breastfeeding and worried about supply, your midwife or health visitor can assess latch, feeding frequency, and milk transfer. The answer is not always supplementation — increasing feeding frequency is often enough to get weight gain back on track.
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What Helps
There is no shortcut to faster weight regain. What works is feeding frequently and effectively.
SST recommends at least 8–12 feeds per 24 hours in the early days for breastfed babies (SST, Amning — en håndbog for sundhedspersonale). This frequency does two things: it gives the baby the intake they need to begin gaining, and it signals the body to increase milk production. Waking a sleepy newborn to feed is not optional in the first two weeks — it is the work.
Skin-to-skin contact in the early days can encourage a reluctant feeder and supports milk production (SST, Amning — en håndbog for sundhedspersonale). It also helps with temperature regulation — which uses energy a newborn working to regain weight doesn't need to spend elsewhere.
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Frequently Asked Questions
How much weight do newborns typically lose after birth?
Breastfed newborns typically lose 7–10% of their birth weight in the first few days, with the lowest point usually around day 2–3. Formula-fed babies generally lose less — around 2–5%. A loss of more than 10% warrants clinical assessment.
When should my baby be back to their birth weight?
Most babies regain their birth weight by around two weeks. If your baby hasn't regained by three weeks, speak to your midwife or health visitor.
Does more weight loss mean my milk isn't coming in?
Not necessarily. Some weight loss is fluid shedding, not milk-related. If your baby is feeding 8–12 times a day, producing adequate wet nappies, and your midwife is happy with the trajectory, the weight will follow. Concern is warranted if the loss exceeds 10% or if regain is significantly delayed.
My baby is losing weight faster than expected. What should I do?
Contact your midwife. A loss of more than 10%, fewer wet nappies than expected, or a baby who is difficult to rouse for feeds are all reasons to be seen promptly. Feeding assessment — latch, frequency, transfer — is the first step, and there is usually something to adjust before supplementation becomes necessary.
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Sources
- Sundhedsstyrelsen. Amning — en håndbog for sundhedspersonale. 2023. https://www.sst.dk/udgivelser/2023/amning-en-haandbog-for-sundhedspersonale
- Sundhedsstyrelsen. Ernæring til spædbørn og småbørn — en håndbog for sundhedspersonale. 2019. https://www.sst.dk/da/udgivelser/2022/Ernaering-til-spaedboern-og-smaaboern-en-haandbog-for-sundhedspersonale
- Sundhedsstyrelsen. Gulsot hos spædbørn. https://www.sst.dk/da/Fagperson/Graviditet-og-smaaboern/Barnets-sundhed/Forebyggende-sundhedsydelser/Observation-og-behandling-af-spaedboern/Gulsot-hos-spaedboern
- Flaherman VJ, et al. "Early Weight Loss Nomograms for Exclusively Breastfed Newborns." Pediatrics. 2015. https://pmc.ncbi.nlm.nih.gov/articles/PMC4279066/
- National Guideline Alliance (UK). "Weight loss in the early days of life." In: Faltering Growth — Recognition and Management. NICE, 2017. https://www.ncbi.nlm.nih.gov/books/NBK536449/