Some babies have a condition called gastroesophageal (GASS-troh-uh-SOF-uh-JEE-uhl) reflux disease (GERD). GERD happens when the muscle at the opening of the stomach opens at the wrong times. This allows milk and food to come back up into the esophagus, the tube in the throat.

Some symptoms of GERD include:

• Severe spitting up or spitting up after every feeding or hours after eating
• Projectile vomiting, where the milk shoots out of the mouth
• Inconsolable crying as if in discomfort
• Arching of the back as if in severe pain
• Refusal to eat or pulling away from the breast during feeding
• Waking up often at night
• Slow weight gain
• Gagging or choking or having problems swallowing

Many healthy babies might have some of these symptoms and not have GERD. Also, some babies with only a few of these symptoms have a severe case of GERD. Not all babies with GERD spit up or vomit. More severe cases of GERD may need to be treated with medicine if the baby refuses to nurse, gains weight poorly or is losing weight, or has periods of gagging or choking.

See your baby's doctor if your baby spits up after every feeding and has any of the other symptoms listed in this section. If your baby has GERD, it is important to continue breastfeeding. Infant formula is harder to digest.

source: http://www.womenshealth.gov