Generally, conditions that put pressure on the on the lower esophageal sphincter or that make digestion more difficult increase your risk of experiencing reflux. The known risk factors for GERD include:

• Obesity/overweight: Having more fat in the chest and abdomen increases the pressure on the stomach and diaphragm and can force open the lower esophageal sphincter, causing reflux.
• Hiatal hernia: When the stomach protrudes through the diaphragm, the resulting pressure can weaken the lower esophageal sphincter and increase reflux.
• Pregnancy: in addition to compressing all the abdominal organs, pregnancy also increases the levels of the hormone progesterone, which relaxes smooth muscles including the lower esophageal sphincter causing reflux.
• Delayed stomach emptying: any condition that causes food to stay in the stomach longer increases the chances that the stomach contents will reflux up into the esophagus. Possible causes include abnormal nerve or muscle function, diabetes, and stomach ulcers.
• Connective tissue disorders: diseases of the connective tissue can keep digestive smooth muscle from relaxing and contracting as it should, increasing the risk of reflux through the lower esophageal sphincter.
• Zollinger-Ellison syndrome. This rare disorder causes your stomach to overproduce acid, increasing the risk of acid reflux.