High doses of aspirin can cause birth defects. Aspirin also can cause bleeding problems for you and the baby before and after delivery. Acetaminophen, e.g., Tylenol, generally is safe to take in small doses during pregnancy, but check with your doctor before taking any medication. Heartburn is a common problem of pregnancy. Beware of antacids that contain a lot of sodium, such as Bromo Seltzer, Alka Seltzer, or Fizrin.
Some antacids also contain aspirin and caffeine.
Tums and Amphojel can be used in moderation. They contain calcium, but too much can cause constipation. The best way to avoid constipation is to eat a balanced diet, with lots of fresh fruits, vegetables, and high-fiber foods, and drink plenty of fluids. If constipation continues to be a problem, talk to your doctor before using any laxatives. Some laxatives can interfere with the absorption of vitamins and minerals essential to fetal development and your ongoing health.