Heartburn is a common complaint among pregnant women. The hormone progesterone causes the valve between the stomach and the esophagus to relax, and as your baby grows and puts pressure on your stomach, it can cause gastric acid to be pushed up into your esophagus, resulting in the painful burning sensation. While prevention is the best way to handle heartburn, antacids are effective and safe (when taken in moderation) to treat the burn during pregnancy.
Antacids are rated in terms of their acid neutralizing capacity (ANC) and come in two types: those that chemically neutralize gastric acid, such as sodium bicarbonate; and those that absorb the acid (non-absorbable antacids), such as calcium and magnesium salts. Most doctors and midwives instruct their patients to use a non-systemic antacid (one not absorbed by the body) such as over-the-counter Tums, Rolaids, Maalox and Phillips' Milk of Magnesia. These antacids contain calcium carbonate, magnesium hydroxide, or magnesium oxide.
Avoid any medications, such as Alka-Seltzer, that contain aspirin (look for salicylate or acetylsalicylic acid on the label) which can be harmful to your baby. In addition, medications that contain sodium bicarbonate and sodium citrate are high in sodium and, while they aren't harmful to your baby, they can make you retain water and swell. Antacid suspensions (liquid form) usually perform better than powders or tablets. However, if tablets are your form of choice, remember to chew them thoroughly to increase their effectiveness. Another way to increase the effectiveness of any antacid is to take it one hour after a meal. The gastric emptying time is faster in an empty stomach, thus allowing the antacid to remain in your stomach for only 20 to 40 minutes. But with a full stomach, as after a meal, the gastric emptying time is slower and the antacid's effects may last up to three hours.
Remember, talk to your OB or midwife about your heartburn and his or her recommended method of treatment. Antacids can interact with other drugs and have other health implications, so talk to your doctor and get the 'ok' to use them during pregnancy.