Magnesium and pregnancy.

Human pregnancy is characterized by several cardiovascular changes, among them a 50% increase in cardiac output, a decrease in the systemic vascular resistance, a 40% blood volume expansion, a decrease in mean arterial blood pressure and a 10-15 beats/min increase in heart rate. It is possible that alterations in magnesium metabolism may be responsible for some of the physiological changes seen during pregnancy and in many diseases related to cardiovascular abnormalities. Magnesium (Mg2+) has been used extensively in obstetrics for the treatment of alterations of uterine contractility (premature labor) or increased neuronal and vascular smooth muscle activity (pre-eclampsia). This review focuses on some of the alterations seen in Mg2+ metabolism during pregnancy. In addition, some of the problems regarding Mg2+ metabolism and parenteral administration of Mg2+ in the treatment of pre-eclampsia and eclampsia are discussed. The use of Mg2+ during labor and as prophylaxis to prevent rupture of membranes and premature labor are also reviewed and discussed.