Why does my baby's hiccups have a sour or foul smell?

Reasons for babies having hiccups with a sour or foul smell: 1. Gastroesophageal reflux is one of the common causes. Babies' stomachs are not fully developed, making it easy for stomach contents to flow back into the esophagus, resulting in hiccups with a sour smell. Adjusting feeding posture and keeping the baby upright after feeding may help reduce reflux. 2. Indigestion may also lead to hiccups with a sour odor. Babies have relatively weak gastrointestinal function, and excessive or hard-to-digest food intake can cause food fermentation in the stomach, producing a sour smell. Controlling food quantity and choosing easily digestible foods can help improve this condition. 3. Poor oral hygiene or infection may also cause sour-smelling hiccups. Fermentation of food residues or bacterial infection in the mouth can lead to foul breath. Maintaining oral cleanliness, regularly cleaning the gums and tongue, can help prevent oral problems. If the baby's hiccups with a sour smell persist or are accompanied by other symptoms, timely medical attention is advised.