Every baby is unique, and so is their growth. Still, it’s natural for parents to wonder whether their baby’s weight is within a healthy range. This guide breaks down what you need to know about baby weight in the early months, based on UK-approved guidance to help you feel informed and reassured.
Newborn Weight Loss and Gain
It’s completely normal for newborns to lose a little weight in the first few days after birth. Most babies regain their birth weight by around two weeks of age. After that, you can expect a steady increase in weight as your baby feeds and grows. (NHS, 2023)
- From 2 weeks to 6 months: Babies usually gain around 150–200 grams (5–7 ounces) per week.
- By 5 months: Many babies double their birth weight.
- By 12 months: Most will have tripled it.
How Often Should Babies Be Weighed?
It’s tempting to weigh your baby all the time—but this can lead to unnecessary worry. The NHS recommends the following as a maximum frequency for routine checks:
- Up to 6 months old: Once a month
- 6–12 months old: Every two months
- Over 1 year: Every three months
Weight checks are usually done by your health visitor or during routine child health reviews, and they’ll plot your baby’s weight on a centile chart in the Red Book (Personal Child Health Record).
Understanding Centile Charts
Centile charts track your baby’s growth against expected patterns for children of the same age and sex. The centile lines represent typical weight ranges:
- If your baby is in the 50th centile, it means they are right in the middle—heavier than 50% of babies, lighter than the other 50%.
- What matters most is that your baby follows a consistent curve over time—not that they land on any particular number.
Crossing two or more centile lines (either up or down) might suggest a need for further assessment. (RCPCH)
When to Speak to a Health Professional
Contact your health visitor or GP if:
- Your baby hasn’t regained their birth weight by three weeks
- You notice poor weight gain or weight loss
- Your baby seems lethargic, has feeding issues, or isn’t producing enough wet nappies
They’ll help you rule out any issues and guide you on next steps.
What Affects a Baby’s Weight?
Several natural factors can influence your baby’s weight:
- Prematurity: Babies born early may gain weight differently
- Feeding type: Breastfed babies often gain weight at a different rate to formula-fed babies
- Genetics: Family build and size can play a role
- Health conditions: Certain issues may affect weight and feeding
In a Nutshell
If your baby seems happy, alert, and is feeding well, chances are they’re doing just fine. But if you’re ever unsure, don’t hesitate to seek advice. You’re never alone.
Looking for peace of mind? The Village connects you to trusted child care and health experts in just a few taps.
Disclaimer: This blog is for informational purposes only and does not constitute medical advice. Please consult your health visitor or GP if you have concerns about your child’s health.
