Why does baby vomit after feeding?

Babies may vomit after eating formula for several common reasons. The most common is that the stomach is still small and cannot handle too much volume — this is called "regurgitation" (spitting up) and is usually a physiological condition that lasts until around 6-12 months. Improper head position during feeding (if baby is too flat), too rapid feeding, or too much formula can also trigger vomiting.

However, if "projectile vomiting" occurs after every feeding and worsens progressively, it may be a sign of pyloric stenosis (narrowing at the stomach outlet) — this occurs in 2-8 week old babies and must always be evaluated by a pediatrician. Additionally, cow's milk protein allergy can also manifest as vomiting accompanied by diarrhea, fussiness, or skin rash.

A practical note: when feeding your baby, hold them at approximately 30-40 degrees upright with their head higher than their body, keep them upright for 20-30 minutes after feeding, and burp them occasionally — this usually reduces spit-up type vomiting. If the vomit is green or yellow, contains bile (bitter taste and color), contains blood (like coffee grounds), or if your baby is losing weight, see a doctor as soon as possible.