A baby's growth is judged by the trend over time, not by a single measurement. At checkups, weight, length and head circumference are measured and compared with growth curves for babies of the same age and sex. The percentile shows where your baby stands in that comparison. For example, the 50th percentile means half of babies the same age weigh less and half weigh more.
Losing about 5 to 10 percent of birth weight in the first days is normal. Most babies are back to birth weight within 10 to 14 days. Growth is fast in the months after: in the first year, length increases by about 25 cm (10 in) and head circumference by about 12 cm (4.7 in). During this time, whether your baby follows their own curve matters more than which percentile they're on. Logging measurements after checkups lets you see that curve too.
For babies born early, growth is assessed by corrected age. That means the number of weeks your baby was born early is subtracted from their actual age. This keeps a premature baby from looking smaller than they really are. Percentiles become meaningful once the baby reaches 40 weeks. Before that, doctors use special curves made for premature babies. Corrected age is usually used until age 2.
What you can do
- Log weight, length and head circumference with the date.
- Each measurement gets a percentile based on WHO growth curves.
- A growth chart shows all measurements over time on one screen.
- Shows percent loss or gain compared with birth weight.
- Gives a warning for a loss of 10 percent or more in the first 2 weeks.
- For premature babies, percentiles use corrected age.
How to use it
- Enter birth weight so loss in the first weeks is tracked.
- Add a new measurement with + after every checkup.
- See the latest percentile and the change from birth weight.
- Follow the trend on the growth chart.
Frequently asked questions
How much weight should a baby gain per month?
In the first months, babies usually gain about 150 to 200 grams (5 to 7 oz) a week, or about 600 to 800 grams a month. After 4 to 6 months, the rate of gain slows. These are averages, and every baby grows at their own pace. What matters is that your baby gains steadily and follows their growth curve. If you're unsure, review it with your doctor.
What percentile should my baby be in?
There is no single right percentile. Anywhere between the 3rd and 97th percentile is usually considered the normal range. A baby on the 15th percentile can be just as healthy as one on the 85th. What matters is that your baby follows their own curve. If there's a drop or rise that crosses two major percentile lines, your doctor will look at it more closely.
How much weight do newborns lose after birth?
Newborns can lose about 5 to 10 percent of their birth weight in the first days after birth, and this is normal. The loss usually reaches its lowest point on days 3 to 5, and most babies are back to birth weight within 10 to 14 days. A loss of 10 percent or more, or not regaining birth weight by 2 to 3 weeks, means feeding should be checked.
What is a normal head circumference for a baby?
At birth, head circumference is usually between 33 and 37 cm (13 to 14.5 in). It grows by about 12 cm in total during the first year, mostly in the early months. Like weight and length, head circumference is assessed with percentile curves. Growth rate matters more than a single number. If very fast growth or a stop is noticed, the doctor will look further.