There are certain underlying factors which can lead to indigestion and heartburn:
Smoking - the chemicals in tobacco can increase the amount of acid produced by the stomach and also prevent the oesophageal sphincter from working properly.
Being overweight - the extra pressure on the stomach can cause indigestion. If this pressure pushes acidic stomach contents back up the oesophagus, heartburn can occur.
Diet - what you eat and the way you eat has an effect on your digestive system. Over-indulgence in certain foods including spicy or greasy foods can increase the amount of acid your stomach produces. In addition, if you do not chew your food properly before swallowing, the stomach has a harder job to break it down, and this may lead to indigestion.
Chocolate and coffee can also hamper the function of the oesophageal sphincter.
Alcohol consumption - alcohol can increase the amount of acid your stomach produces.
Stress - stress or anxiety can disturb your nervous system and impact upon stomach contractions during digestion
Pregnancy - heartburn and indigestion may be caused due to the pressure of the baby on the stomach. Hormonal changes may cause a relaxation of the oesophageal sphincter and iron tablets taken during pregnancy may also cause indigestion.