The Magpie Trial

In the trial population as a whole, there was indeed a significant reduction in the incidence of eclampsia (1·9% in the placebo group, 1·1% with magnesium), although there was no significant difference in maternal or perinatal mortality. The investigators ensured that treatment allocation was balanced for several variables including severity of pre-eclampsia and country. [...]just before the final analysis, three subgroups of the participating countries were defined as having “low, moderate, or high” perinatal mortality. Perhaps treatment of hypertension is more effective in “first world” nations, or perhaps delivery is delayed in countries with high perinatal mortality. 25% of the women in each group received no antihypertensive treatment.