A randomized cross over trial of tolerability and compliance of a micronutrient supplement with low iron separated from calcium vs high iron combined with calcium in pregnant women [ISRCTN56071145]

Background: Prenatal micronutrient combinations with high iron content are associated with high rates of gastrointestinal symptoms. This coupled with nausea and vomiting of pregnancy results in women often discontinuing their multivitamins. A new prescription supplement (PregVit®) that separates iron from calcium in two tablets - morning and evening, has lower elemental iron content (35 mg), but results in similar extent of iron absorption when compared to another supplement containing (60 mg) of elemental iron (Materna®). The objectives of this study were to compare tolerability and compliance with PregVit® vs. a supplement with high iron content (Materna®), in pregnant women. Methods: Randomized, crossover open labeled study in 135 pregnant women attending outpatient clinics in Ontario and Quebec. Results: Use of PregVit® was associated with a 30% reduction in constipation rate as compared to Materna®. Both products demonstrated similar compliance rates. Compliance of Materna® was negatively associated with the severity of nausea and vomiting of pregnancy. No such correlation was found for PregVvit®. Conclusion: PregVit®, a supplement with lower iron content (35 mg), has significantly decreased constipation rates as compared to 60 mg iron- Materna and has similar compliance rates. High iron content in multivitamin supplements is associated with adverse effects in pregnancy.