Vitamin/Mineral Supplements and Calcium-Based Antacids Increase Maternal Calcium Intake

Objective: The contributions of over-the-counter (OTC) calcium-based antacid medications and calcium-containing vitamin/mineral supplements to total calcium intake during pregnancy, have rarely been assessed. This study estimates the contributions of calcium-based antacids and vitamin/mineral supplements to maternal calcium intake.

Methods: Over an 8-month period, a cohort of 724 prenatal class attendees (out of a possible 1100 participants) at >28 weeks gestation in Calgary, Alberta, completed an anonymous questionnaire on vitamin/mineral supplement intake and the use of calcium-based antacids. A subset of 264 women completed a self-reported calcium-modified food frequency questionnaire.

Results: The use of prenatal vitamins/minerals increased during pregnancy as did use of the single nutrients calcium and iron. Calcium-based antacids were used by 52% (n = 365) of pregnant women. Median intake of calcium from maternal diet alone was 1619 mg/d (mean intake, 1693 ± 94), which rose to 2084 mg/d (mean intake, 2228 ± 116) when diet, vitamin/mineral supplements, and antacids were considered. From diet alone, 18% had less than adequate intake (AI = 1000 mg/d) of calcium and 12% exceeded the tolerable upper intake level (UL = 2500 mg/d). Adding antacids reduced to 5% those below the AI and increased those surpassing the UL to 33%. No adverse events were reported at calcium intakes above the UL.

Conclusions: Vitamin/mineral supplements and calcium-based antacids increased total maternal calcium intake, resulting in fewer women with intakes < AI but also increasing the number of those with intakes > UL. It is suggested that health care providers discuss all sources of nutrient intake with pregnant clients, as cumulative intakes may unintentionally exceed recommended levels.