TAREA 15: CALCIUM SUPPLEMENTATION TO PREVENT HYPERTENSIVE DISORDERS OF PREGNANCY

Methods

We conducted a multicenter, double-blind, randomized controlled trial to assess the effect of supplementation with 2 g of elemental calcium per day on the incidence of hypertensive disorders of pregnancy (gestational hypertension and preeclampsia). Women were considered to have gestational hypertension if measurements of blood pressure on two occasions at least six hours apart revealed a systolic blood pressure 140 mm Hg and diastolic blood pressure 90 mm Hg after the 20th week of gestation in the absence of proteinuria. Women were considered to have preeclampsia if they met the criteria for gestational hypertension and had proteinuria (protein, 0.3 g per liter) on examination of at least two separate (more than six hours apart) random urine specimens obtained after the 20th week of gestation. The women were enrolled at three affiliated hospitals of the Centro Rosarino de Estudios Perinatales, Rosario Argentina. Two are public institutions serving patients with low socioeconomic status, and the other hospital is private, serving patients of medium-to-high socioeconomic status.

Pregnant women who sought prenatal care before the 20th week of gestation between January 1987 and September 1989 were screened for possible enrollment. They were eligible for the study if they were nulliparous, had singleton pregnancies, were less than 20 weeks pregnant at the time of the first interview, and had blood pressures below 140/90 mm Hg (mean of five measurements). Gestational age was estimated from the date of the last menstrual period and confirmed by ultrasonography; women in whom the two estimates of gestational age differed by more than 1 O days were excluded from the study. None of the women had any clinical or laboratory evidence of present or past disease, none were taking any medications, and all had normal oral glucose-tolerance tests. The study was approved by the Joint Human Voluntary Committee of the Centro Rosarino de Estudios Perinatales and the participating hospitals, and all the women gave informed, written consent.