Over 8300 women with low dietary calcium (<600 mg/day, about half of that recommended during pregnancy) were selected for the study. The subjects were randomly divided into two groups that had similar gestational ages, demographic characteristics, and normal blood pressures before treatment started. Half were given 1.5g of a calcium supplement per day and half received a placebo.
While the incidence of preeclampsia was not statistically different in the supplemented women, eclampsia, other severe complications and severe gestational hypertension were significantly lower. Overall, the "severe preeclamptic complications index" and the "severe maternal morbidity and mortality index," including all severe conditions, were also reduced with calcium.
Preterm and early preterm delivery (<32 weeks) tended to be reduced among women 20 years of age who were at highest risk for low calcium and complications. It is very important to note that neonatal mortality was also lower in the calcium group.
This multicenter, randomized, placebo-controlled, double-blind trial was performed at antenatal care centers located in Rosario, Argentina; Assiut, Egypt; Nagpur and Vellore, India; Lima, Peru; East London and Johannesburg, South Africa; and Ho Chi Minh City, Vietnam. These centers are part of the WHO Maternal and Perinatal Research Network, each having extensive clinical trial experience.
Writing in the article, Jose Villar, MD, states, "This large randomized trial in populations with low calcium intake demonstrates that while supplementation with 1.5 gm calcium/day did not result in a statistically significant decrease in the overall incidence of preeclampsia, calcium significantly decreased the risk of its more serious complications, including maternal and severe neonatal morbidity and mortality, as well as preterm delivery, the latter among young women."