How is failure to thrive different in infants?

Infants grow quickly, so clinicians look at weight, length and head growth over time rather than one measurement. A baby may gain weight slowly, cross growth lines, feed for a long time, tire during feeds, vomit frequently or have fewer wet nappies. Some infants take too little milk; others cannot absorb or use nutrients because of reflux, infection, heart or lung disease, swallowing difficulty, allergy or another condition.

A small baby is not automatically failing to thrive, and a naturally larger baby can still have faltering growth. The pattern, feeding history, examination and development provide the context.

Arrange a prompt paediatric or primary-care review. Bring the feeding schedule, breast or formula details, how much is taken, vomiting or stool changes, wet-nappy pattern and any feeding videos or records. The clinician may observe a feed, check the mouth and heart, plot measurements, and assess development and hydration. Support may involve feeding technique, lactation or dietetic input, treatment for an underlying problem, or closer weight checks. Do not dilute formula or add supplements without professional guidance.

Seek urgent care if the infant is difficult to wake, breathing fast or struggling to breathe, has markedly fewer wet nappies, repeated green or bloody vomit, blue or grey skin, a swollen abdomen, or cannot keep feeds down. A young infant with fever also needs prompt medical advice. These signs concern hydration, breathing or infection rather than weight alone.

Ask whether the growth pattern is faltering, whether a feed should be observed, how to measure intake and wet nappies, which causes need testing, and when the next weight and development review should occur.