Calcium supplementation is associated with a significant protective benefit in the prevention of pre-eclampsia, and should be used for this indication according to a previous review. This review indicates that there are no additional benefits for calcium supplementation in prevention of preterm birth or low infant birth weight. While there was a statistically significant difference of 80 g identified in mean infant birth weight, there was significant heterogeneity identified, and the clinical significance of this difference is uncertain.
Calcium and low-dose aspirin prophylaxis in women at high risk of pregnancy-induced hypertension.
The objectives of the study were to confirm the validity of using oscillometric measurement of MAP in the left lateral position to identify those at high risk for developing pregnancy-induced hypertension (PIH), and to assess and compare the efficacy of prophylaxis with low-dose aspirin or calcium supplementation in high-risk patients.
                A prospective study in pregnancy; 500 normotensive, primigravid Chinese women were recruited in the second trimester of pregnancy on the basis of 80 mm Hg > or = MAP < 106 mm Hg in the antenatal clinic. They were then screened by Dinamap in a research setting, measuring MAP in the left lateral position after rest and using a cutoff value of 60 mm Hg for inclusion in the randomized study. Randomization was divided into three groups: control, low-dose aspirin, and calcium supplementation. After delivery, patients were classified as either having remained normotensive or having developed PIH, with or without proteinuria.
                The incidence of both proteinuric and nonproteinuric PIH was significantly lower in patients screened out as low risk than in those selected as high risk using a critical value of 60 mm Hg for left lateral MAP (p < 0.05). The incidence of proteinuric PIH was significantly lower in patients given low-dose aspirin than in the control group (p < 0.05). However, the confidence intervals for the effect were wide, comparable with aspirin having no effect or leading to a 16-fold reduction in the risk of preeclampsia. For those given calcium supplementation, the reduction was not significant. There was no significant difference in the incidence of nonproteinuric PIH between the control group and the two groups receiving prophylaxis.
                Oscillometric measurement of second-trimester left lateral MAP is a valid predictor of proteinuric PIH. Low-dose aspirin may offer a degree of protection from proteinuric PIH in these high-risk women. Calcium supplementation was not shown to significantly reduce the incidence of PIH.