Breastfeeding in 5-month-old babies may be normal or abnormal, and needs to be analyzed on a case-by-case basis. The development of a 5-month-old baby is not particularly mature, the control over vomiting is weak, and the development of stomach muscles is not very mature, the baby will be prone to milk overflow. Under normal circumstances, as the baby grows up, the symptoms of milk overflow will gradually improve, around 6-12 months, milk overflow can occur after excessive and frequent breastfeeding, and the symptoms can be improved through regular feeding. If the baby shows frequent vomiting, or severe projectile vomiting, and the milk overflow does not improve after changing feeding habits, it may be due to incomplete pyloric development or even dysfunction, which is a more serious condition and requires further treatment. 5-month-old babies can not accurately express their own discomfort, if the baby appeared overflow, parents are advised to pay attention to, go to the regular hospital to consult a doctor, in order to exclude the possibility of pathological factors.