Magnesium is the second most abundant cation of intracellular fluids. The human body contains 20 to 28g of magnesium, of which 50-60% is in bone, 40- 45% exists as an intracellular cation in muscle and soft tissues, and 1% is in extracellular fluid. Magnesium is essential for the activity of many enzymes. It influences protein and carbohydrate metabolism, plays an important role in neurocheniical transmission, depresses muscular excitability, and through its peripheral vasodilatory action, affects the cardiovascular system.  Research indicates it may also control cholesterol and heart arrhythmia.

Magnesium deficiency includes hypomagnesaemia, hypomagnesuria, hypocalcaemia and hypokalaemia. Hypocalcaemia in magnesium deficiency appears to result from reduced magnesium-calcium exchange. i.e. reduced exchange of calcium for magnesium at unstable bone mineral surfaces. After appropriate magnesium supplementation, plasma magnesium levels rise rapidly, plasma calcium concentrations are corrected after some delay.

Overall, the close relationship between magnesium and calcium homeostasis has potentially major clinical significance. The value of magnesium supplementation for correction of hypocalcaemia in certain clinical settings can not be ignored.

Magnesium in Pregnancy

Magnesium supplementation during pregnancy may be able to reduce fetal growth retardation and pre-eclampsia, and increase birth weight.

A severe deficiency may lead to preeclampsia, congenital malformations, and infant mortality.

The RDA of magnesium is 280 mg for nonpregnant women, 300 mg for pregnant women, and 355 mg for nursing women.
Magnesium and calcium work in combination: Magnesium relaxes muscles, while calcium stimulates muscles to contract. Research indicates that proper levels of magnesium during pregnancy can help maintain uterine relaxation until week 35. Dropping levels at this point may help the onset of labor.
Dietary supplements taken during pregnancy may reduce premature births and birth defects, federal research finds.

Magnesium sulphate has been used for treating eclampsia in the United States for much of the 20th century. Pre-eclampsia is a complex, multisystem disorder and how magnesium sulphate may prevent eclamptic convulsions is unclear. Magnesium may have localised effects, producing cerebral vasodilatation with subsequent reduction of cerebral ischaemia, or blocking of neuronal damage associated with ischaemia. However, magnesium sulphate also affects many other organs, and it would be implausibly fortuitous if these effects were exclusively beneficial.Women getting magnesium sulfate also had a 45 percent lower risk of dying11 died, compared with 20 in the comparison group.

During pregnancy, adequate levels of magnesium help prevent premature contractions and help delay preterm births and at-risk low birth weight babies. Low magnesium intake has also been shown to contribute to eclampsia and convulsions occurring in pregnant women with preeclampsia, which is high blood pressure due to pregnancy.

Disclaimer: This information is intended as a guide only.   This information is offered to you with the understanding that it not be interpreted as medical or professional advice.  All medical information needs to be carefully reviewed with your health care provider.