Newborn weight gain: norms by month and when to worry
Updated
Weight is the most common source of worry in the first months: it can feel like the baby is gaining too little, weighs less than the neighbour’s child, or "isn’t up to the chart". In reality the norm is a wide band, and what matters within it is not a single number but how the baby grows along their own curve.
Below: how weight normally changes in the first days and months, how much a baby gains by age, how to tell that feeding is enough, and the signs at which poor weight gain stops being a normal variation and becomes a reason to see a doctor.
Why weight drops in the first days
Right after birth a baby loses weight, and that is normal. In the first days extra fluid is shed, meconium passes, and there is not much milk yet — a healthy full-term baby loses up to 7–10% of birth weight. It is not a sign that they are starving.
Weight then starts to climb, and by around 2 weeks most babies are back to their birth weight. That is where the count of gains really begins: what matters is not so much the absolute number on the scale as the fact that the curve has turned upward and is holding.
How much a baby normally gains
Once birth weight is regained, in the first 3 months a baby gains roughly 20–30 g a day, that is about 150–200 g a week. After that the pace naturally slows: the body grows fastest at the very start, and later the gains get smaller — this is not a decline but the norm.
The "doubling" and "tripling" landmarks: by 4–5 months a baby usually doubles their birth weight, and by 1 year triples it. These are average milestones, not a bar to clear: full-term and premature babies, boys and girls, breastfed and formula-fed babies all grow differently.
| Age | Gain per week | Gain per day |
|---|---|---|
| 0–3 months | ≈ 150–200 g | ≈ 20–30 g |
| 3–6 months | ≈ 100–150 g | ≈ 15–20 g |
| 6–12 months | ≈ 70–90 g | ≈ 10–13 g |
These are averages, not a target to make the baby fit. In healthy babies gains swing from week to week, and one "weak" week on its own means nothing — what counts is the trend over several weeks.
Percentile curves: why the trend matters, not the number
At check-ups the paediatrician plots weight on a percentile curve — a chart that shows how the baby grows relative to thousands of other children of the same age and sex. A baby on the 10th percentile is not "worse off" than a baby on the 90th: both are healthy, one is simply built lighter than the other.
The key thing on the chart is not which band the baby sits in, but that they track steadily along their own curve. A baby who grows steadily on the 10th percentile is normal. What is concerning is different: when the curve drops sharply, crossing percentile lines downward. It is this trend, not a one-off comparison with a chart or with someone else’s baby, that the doctor assesses.
How to tell that feeding is enough
The scale is not the only, or the handiest, day-to-day guide. It is simpler to watch the baby themselves and the nappies: if there are enough wet and dirty nappies, the baby is alert and active between feeds, feeds well and grows steadily — feeding is almost certainly enough.
- Enough wet nappies — once the milk has come in, usually around 6 or more heavily wet nappies a day.
- Regular stools — in the first weeks a baby usually dirties the nappy several times a day; the frequency changes over time.
- Alert and active — lively and responsive during waking periods, not constantly floppy.
- Feeds well — takes the breast or bottle willingly, and you can hear swallowing during the feed.
- Grows steadily — at weigh-ins the curve tracks along its own band.
Do not make the baby fit the chart
Charts and curves are a tool for the doctor, not a reason for decisions at home. Do not top up or restrict the baby based on numbers alone: overfeeding "to catch up with the chart" is as unhelpful as anxiety over one average week. Weight at check-ups is measured and interpreted by the paediatrician — they see the whole curve and read it in the context of the child’s growth, wellbeing and development.
When poor weight gain is a reason to see a doctor
See a doctor if the baby has not returned to birth weight by 2–3 weeks, if weight keeps falling after the initial newborn dip, if the curve drops steadily downward across percentile lines, if there are suddenly too few wet nappies, or if the baby is lethargic, feeds poorly, or is hard to rouse for a feed. These are not normal variations but signs that something is wrong with feeding or health.
It is also worth seeing a doctor if weight is a constant source of worry for you: a weigh-in and an examination usually reassure, and if there is a problem, it is better caught early.
How the app helps you stop guessing
Weight gain cannot be judged from a single day, and keeping feeds and nappies in your head on no sleep is unrealistic. Logging feeds and nappy changes shows earlier if the baby has suddenly started feeding less or the wet nappies have dropped noticeably below usual — a reason not to panic but to see the doctor in good time. And at the appointment, instead of "seems to feed all right", the paediatrician has a real record that makes the weight curve easier to explain.
Baby Tracker keeps these records for you
Feeds, sleep and nappies in two taps, a day-by-day view of the routine, and shared access for the whole family. Free, right inside Telegram — no install, no sign-up.
Open in TelegramFrequently asked questions
How much should a newborn gain per week?
In the first 3 months, on average around 150–200 g a week (roughly 20–30 g a day), then the pace slows: about 100–150 g at 3–6 months and about 70–90 g a week at 6–12 months. These are guides, not a strict target — gains swing from week to week.
Why does a newborn lose weight in the first days?
It is normal: extra fluid is shed, meconium passes, and there is not much milk yet. A healthy full-term baby loses up to 7–10% of birth weight and usually returns to it by around 2 weeks.
When does a baby double their birth weight?
On average birth weight doubles by 4–5 months and triples by 1 year. These are average milestones: the timing differs between babies, and small departures from them are a normal variation.
My baby is on a low percentile — is that bad?
Not in itself. A baby on the 10th percentile is just as healthy as one on the 90th, simply built lighter. What matters is not which band they are in but that they grow steadily along their own curve. Only a sharp downward drop of the curve is concerning.
How do I know my baby is getting enough to eat?
By enough wet and dirty nappies, by the baby being alert and active between feeds, feeding willingly and growing steadily at weigh-ins. There is no need to weigh daily — weight is assessed by the paediatrician at check-ups.
Sources
- Child growth standards — WHO
This article is for general information and does not replace medical advice. Your baby’s weight and growth are assessed by the paediatrician on their own percentile curve, not on a single number or comparison with other children. Discuss any concern about your baby’s feeding, weight gain or wellbeing with your own doctor.