vitababyIn short
Reflux — milk coming back up after feeds — is very common and usually harmless, and most babies with it still gain weight normally. It can affect weight gain when it makes feeding painful or distressing enough that a baby takes less milk. Bringing up milk with poor weight gain, frequent discomfort, or feed refusal is worth reviewing with your GP, who can suggest feeding changes and, if needed, treatment, and consider whether something else such as cow’s milk protein allergy is involved.
Key takeaways
- Reflux is common and usually harmless; most babies with it gain weight normally.
- It affects weight mainly when feeding becomes painful and a baby takes less milk.
- Poor weight gain alongside reflux is a reason to see your GP.
- Reflux symptoms can overlap with cow’s milk protein allergy, which is worth considering.
Why reflux usually does not affect weight
Posseting — bringing up small amounts of milk after feeds — is normal in babies because the muscle at the top of the stomach is still developing. It looks dramatic but most babies are comfortable, feed well, and gain weight as expected. Reflux like this usually needs no treatment and settles over the first year.
When reflux can slow weight gain
Reflux becomes worth attention when it interferes with feeding: a baby who is uncomfortable, arches or cries during feeds, refuses the breast or bottle, or brings up large amounts may take in less milk over time, and weight gain can slow. Signs that feeding is being affected — not the spitting up itself — are what matter for weight.
- Frequent discomfort, arching, or crying during or after feeds.
- Refusing feeds or feeding only small amounts before stopping.
- Slow weight gain or downward centile crossing alongside reflux.
Reflux or cow’s milk allergy?
Reflux symptoms can overlap with cow’s milk protein allergy (CMPA), which can also cause discomfort, feeding problems, and slow weight gain. Clues that point more towards allergy include other symptoms such as eczema, persistent diarrhoea or mucus in stools, or symptoms that do not improve with usual reflux measures. Our guide on cow’s milk protein allergy and slow weight gain covers this comparison in detail.
What helps and when to see your GP
Simple measures often help: smaller, more frequent feeds, keeping your baby upright for a short while after feeding, and checking positioning and latch. See your GP if your baby is gaining weight slowly, refusing feeds, distressed at most feeds, or not improving — they can advise on feeding changes, consider allergy, and prescribe treatment if it is needed. Reflux is rarely a reason to stop breastfeeding.
VitaBaby lets you log feeds, amounts, and notes about discomfort alongside the weight trend, so any link between difficult feeds and slowing gain is easy to spot and share with your GP.
FAQ
Can reflux cause a baby to lose weight?
Most babies with reflux gain weight normally. Reflux can slow weight gain — and occasionally cause weight loss — when it makes feeding so uncomfortable that a baby takes much less milk. Poor weight gain with reflux should be reviewed by your GP.
What is silent reflux?
Silent reflux is when milk comes back up but is swallowed again rather than spat out, so there is little visible posseting. A baby may still show discomfort during or after feeds. If feeding and weight gain are affected, speak to your GP.
How do I know if it is reflux or a milk allergy?
They can look similar. Additional symptoms such as eczema, blood or mucus in stools, persistent diarrhoea, or a lack of improvement with usual reflux measures point more towards cow’s milk protein allergy. Your GP can help tell them apart.
Sources
- Reflux in babies — NHS
- Gastro-oesophageal reflux disease in children and young people — National Institute for Health and Care Excellence (NICE)