[Use of calcium for the prevention of pregnancy-induced hypertension].

The Andean population of Ecuador is exposed to major risk factors associated with pregnancy-induced hypertension (PIH). The disease is very frequent, and perinatal and maternal death rates are high. Recently a causal relationship has been suggested between dietary calcium deficiency and PIH, with the proposal that calcium supplements be given throughout pregnancy in order to prevent the disease. This article reviews a series of clinical tests carried out over a six-year period which have demonstrated that calcium supplementation is an effective low-cost measure for reducing the frequency of PIH in women whose intake of the mineral is low. It is not yet known how calcium reduces the risk of PIH. It is suggested that adequate intake of the mineral keeps serum levels of calcium within its narrow physiological limits; these are crucial for the synthesis of nitric oxide in the vascular endothelium, a substance that appears to be responsible for maintaining the vasodilatation that characterizes normal pregnancy. However, before the general use of calcium supplements can be recommended, it will be necessary to conduct epidemiological studies on larger numbers of women.