The effect of calcium supplementation on blood pressure in non-pregnant women with previous pre-eclampsia: An exploratory, randomized placebo controlled study.

BACKGROUND: Epidemiological findings suggest that the link between poverty and pre-eclampsia might be dietary calcium deficiency. Calcium supplementation has been associated with a modest reduction in pre-eclampsia, and also in blood pressure (BP). METHODS: This exploratory sub-study of the WHO Calcium and Pre-eclampsia (CAP) trial aims to determine the effect of 500mg/day elemental calcium on the blood pressure of non-pregnant women with previous pre-eclampsia. Non-pregnant women with at least one subsequent follow-up trial visit at approximately 12 or 24weeks after randomization were included. RESULTS: Of 836 women randomized by 9 September 2014, 1st visit data were available in 367 women of whom 217 had previously had severe pre-eclampsia, 2nd visit data were available in 201 women. There was an overall trend to reduced BP in the calcium supplementation group (1-2.5mmHg) although differences were small and not statistically significant. In the subgroup with previous severe pre-eclampsia, the mean diastolic BP change in the calcium group (-2.6mmHg) was statistically larger than in the placebo group (+0.8mmHg), (mean difference -3.4, 95% CI -0.4 to -6.4; p=0.025). The effect of calcium on diastolic BP at 12weeks was greater than in those with non-severe pre-eclampsia (p=0.020, ANOVA analysis). CONCLUSIONS: There is an overall trend to reduced BP but only statistically significant in the diastolic BP of women with previous severe pre-eclampsia. This is consistent with our hypothesis that this group is more sensitive to calcium supplementation, however results need to be interpreted with caution.

What does an elevated mean arterial pressure in the second half of pregnancy predict--gestational hypertension or preeclampsia?

OBJECTIVE: The purpose of this study was to determine the predictive value of elevated mean arterial pressure in the second half of pregnancy for both preeclampsia and gestational hypertension. STUDY DESIGN: This was a cohort of 588 nulliparous pregnant women studied prospectively from the twentieth week until delivery. Mean arterial pressure was obtained by means of a random-zero sphygmomanometer at 20, 26, and 31 weeks of gestation. The best cutoff point for the determination of predictive values was established by a receiver-operator characteristic curve. RESULTS: Patterns of mean arterial pressure throughout pregnancy were different between preeclamptic and gestational hypertensive women. Receiver-operator characteristic curves for mean arterial pressure showed better predictive capacity for gestational hypertension than for preeclampsia. Sensitivity of mean arterial pressure to predict preeclampsia ranged between 39% and 48%, whereas for prediction of gestational hypertension it varied from 72% to 92%. Specificities for both groups were moderate (60% to 86%). Positive predictive values were low for all groups (5% to 33%). CONCLUSION: Elevated mean arterial pressure in the second half of pregnancy is a good predictor of gestational hypertension but is a poor predictor of preeclampsia.