Oh that chest burn that just wouldn’t go away; what a drag for pregnant moms…
I recommend some prevention,  a few easy remedies, and an AVOID.

Prevention: First try to avoid getting too full – so snack often, eating 6 meals not 3 every day. If you notice that spicy foods or foods that make you burp increase the heartburn, than obviously avoid them. Try not to eat right before laying down, as the sheer pressure of your growing belly on your squished stomach can increase the leakage of acids into your esophagus.  Also see your chiropractor to have your stomach checked for a diaphragmatic hernia because having part of your stomach caught in your diaphragm will definitely cause heartburn.

Remedy: Try having raw almonds in your purse and snacking on them periodically, they contain an enzyme that is somewhat neutralizing to stomach acid, also many people find success with Papaya Enzyme pills or lozenges. Our favorite middle-of-the-night remedy is slippery elm bark powder mixed with a little honey. Mix about about a tablespoon of both in a small bowl until a paste is formed, then gum it down. This is especially helpful for middle of the night heartburn. Some people try a glass of milk, but we have heard that heartburn with acidy-milk burps are almost worse.  And the best immediate fix-on-the-go remedy is just chomping on some chia seeds.  Yes, thats right, the old cha-cha-chai pets of our youth have been re-purposed to eliminate heartburn (an make you laugh while singing the theme song in your head). Bonus:
A 1 ounce (28 grams) serving of chia seeds contains:

• Fiber: 11 grams.
• Protein: 4 grams.
• Fat: 9 grams (5 of which are Omega-3s).
• Calcium: 18% of the RDA.
• Manganese: 30% of the RDA.
• Magnesium: 30% of the RDA.
• Phosphorus: 27% of the RDA.
• They also contain a decent amount of Zinc, Vitamin B3 (Niacin), Potassium, Vitamin B1 (Thiamine) and Vitamin B2.

Avoid: Tums or other antacids with added calcium. The calcium sounds like a good idea but actually is practically non-absorbable and in large doses (as in popping 2 tums every couple days the entire last trimester) forms calcium deposits in the placenta. These deposits of calcium can cause certain small parts of the placenta to die. The calcium deposits may cause some parts of the placenta to be replaced with fibrous tissue. The calcium deposits can also obstruct parts of the placenta with clots of maternal blood which can harden or block the maternal blood vessels. Calcification can be caused by other factors as well, like just postmature pregnancy, or cigarette smoking.  In most cases, placental calcification does not affect the functioning of the placenta, and the fetus is generally not harmed. But I feel it wise to avoid adding that much of a substance that isn’t helpful and can be harmful.