Hormones released during pregnancy allow the softening of the sphincter between the esophagus and stomach. This lets stomach acids back up into the esophagus, causing a burning sensation. This may also occur in the latter months of pregnancy as your baby pushes all of your organs upward.
Suggestions:
Eat smaller, more frequent meals
Remain upright for an hour after eating, lying down can irritate the problem
Eating yogurt or drinking milk can help
Avoid spicy or greasy foods
Try a tablespoon of honey in a glass of warm milk
Mercurius Solubilis 6C three times daily
I copied this off of a site dealing with pregnancy...I have no idea what the last entry is (Mercurius Solubilis?

? Whassat?

?), so don't do anything without passing it by your OB/GYN first.