Rennie can be taken during pregnancy for heartburn and indigestion if taken as instructed. It contains calcium carbonate and magnesium carbonate which neutralize stomach acid. Pregnant women should strictly limit their use of Rennie to the maximum recommended daily dose and avoid excessive intake of calcium through milk or dairy products alongside. It is safe when used as directed but prolonged or excessive use should be avoided, and consulting a doctor or pharmacist is advisable. Rennie Peppermint and Rennie Orange variants both have similar precautions regarding calcium intake during pregnancy.