Gas should not be considered excessive unless it occurs at more than twice the normal frequency. The main causes of normal gas are swallowed air, gas-producing foods, and certain diseases that interfere with sugar absorption. This process is increased by sucking on a clogged nipple, a bottle that does not have milk in it, a pacifier, the thumb, or a blanket. Babies also swallow air during crying. Older children swallow air with gum-chewing.
Some children have a nervous habit of frequent swallowing.
The carbonation in soft drinks releases gas in the stomach. Stomach gas is more likely to pass into the intestines if a child is lying down. These foods are converted into gas by bacteria in the large bowel. Eating beans can increase gas production tenfold. The most common medical condition that causes increased gas production is milk intolerance.