Effects of calcium supplementation on uteroplacental and fetoplacental blood flow in low-calcium-intake mothers: a randomized controlled trial

OBJECTIVE: We postulated that calcium supplementation of calcium-deficient pregnant women would lower vascular resistance in uteroplacental and fetoplacental circulations. STUDY DESIGN: Pulsatility index (PI) and resistance index (RI) (uterine and umbilical arteries) and presence of bilateral uterine artery diastolic notching were assessed by Doppler ultrasound between 20-36 weeks' gestation in 510 healthy, nulliparous Argentinean women with deficient calcium intake in a randomized, placebo-controlled, double-blinded trial. RESULTS: Average umbilical and uterine artery RI and PI tended to be lower in the supplemented group at each study week. Differences be-came statistically significant for umbilical artery RI and PI from 32 and 36 weeks, respectively. Estimated probabilities of bilateral uterine artery diastolic notching trended toward lower values in calcium-supplemented women. CONCLUSION: Calcium supplementation of pregnant women with deficient calcium intake may affect uteroplacental and fetoplacental blood flow by preserving the vasodilation of normal gestation.