There is often no known reason for increases in heartburn. But occasionally one of the factors below may contribute.

Hiatus hernia

This is the name for the condition where the upper part of the stomach has passed up through the hole in the diaphragm.

This means the muscle fibres of the sphincter can't press on the lower part of the food pipe. As a result, the lower part of the gullet is normally open, when it should be closed.

Obesity

In people who are overweight, the fat in their abdominal cavity exerts more pressure on the stomach.

This causes high pressure inside the stomach, and the contents of the stomach may then be pushed up into the food pipe.

Weight loss will reduce the chance of stomach acid reflux.

Pregnancy

The enlarged uterus (womb) presses on the stomach. This causes the same kind of high pressure inside the stomach as in people who are overweight.

The change that pregnancy brings to the balance of the hormones also leads to a general relaxation of the gullet sphincter.

Large meal portions

The risk of stomach acid reflux increases with more food in the stomach.

The risk will be greater after large (and especially fatty) meals, where the food is in the stomach for a long time before it passes on to the intestines.

If you avoid eating more than is necessary, the risk of stomach acid reflux is reduced.

Lying down

If you lie down, the chance of stomach acid reflux increases due to gravity.

You can avoid this to some extent by raising the head-end of your bed (see tips below).