Eating for Two
Heartburn may start to become a persistent problem as your uterus crowds your stomach and the smooth muscles of your digestive tract remain relaxed from the hormone progesterone. Some tips for putting out the fire include:
Avoid greasy, fatty, and spicy foods.
Stay away from alcohol and caffeinated drinks (e.g., cola, tea, coffee); these may relax the valve between the stomach and the esophagus and exacerbate heartburn.
Eat smaller, more frequent meals instead of three large ones.
Drink plenty of water between meals to reduce stomach acid.
Don't eat just before you go to bed or lay down to rest.
Pile a few extra pillows on the bed to assist gravity in easing heartburn while you sleep.
Another option you have is to keep a food diary to try to determine what your heartburn triggers are to avoid them in the future.

