The effects of oral calcium on the prevention of moderate to severe ovarian hyperstimulation syndrome in high-risk patients: A placebo-controlled study

Ovarian Hyperstimulation Syndrome (OHSS) is a serious complication of Assisted Reproductive Technology (ART). Some studies show that intravenous calcium infusion decreases the risk of OHSS in high-risk patients. Some life-threatening complications may occur following intravenous calcium gluconate infusion, but oral calcium carbonate is a cheap and easy-to-use medication with no/minor side-effects. The present clinical trial was therefore designed to identify the role of oral calcium in OHSS prevention in high-risk patients. A total of 99 patients who had received an antagonist protocol for ovarian stimulation in their ART cycles and were at risk of OHSS were recruited for the study. The patients were allocated into two groups to receive either 500-mg BID calcium carbonate tablets or placebo tablets from their puncture date for five days. The findings showed no significant differences in oocyte and grade A, B and C embryo counts between the two groups. Moreover, the clinical pregnancy rate and the frequency of OHSS symptoms were not significantly different between the two groups. The frequencies of mild, moderate and severe OHSS were not significantly different between the two groups either. Since oral calcium is an easy-to-use method with limited side-effects, we recommend further studies to examine its effects on OHSS prevention in high-risk patients.