Magnesium in Pregnancy

Magnesium in Pregnancy

Pregnancy and Magnesium

Magnesium in pregnancy: introduction

Magnesium is considered a very important mineral in pregnancy.

On the other hand, as we will see later, this statement can be considered misleading, since each nutrient performs indispensable and irreplaceable functions. However, only in certain cases, the increase in magnesium intake during pregnancy can prove not only useful but even necessary. Let’s see why.

Magnesium overview

Magnesium (Mg++) is a nutritional mineral that belongs to the group of microelements. It exerts many functions, including participation in enzymatic reactions, nerve and muscle membrane excitability , thermoregulation ,  protein and nucleic acid synthesis , synaptic transmission, alkalization, blood pressure modulation , etc. Magnesium is mainly contained in foods of plant origin, such as legumes , vegetables , whole grains , sweet fruits, oilseeds , algae and cocoa. Absorption occurs in the small intestine and is hindered by the presence of calcium . It is also subject to the influence of certain anti-nutritional agents such as phytates ; on the other hand, the plasma content of vitamin D has a positive effect on absorption . The main routes of excretion are urine and faeces , but vomiting also determines its elimination from the body. Magnesium deficiency is manifested by nausea, vomiting, anorexia, muscle cramps , vasodilation , cardiac arrhythmia , and coma; the excess does not occur in people with normal kidney function . During pregnancy it also performs other roles, most of which are preventive. Let’s see them in more detail.

Need in Pregnancy

Importance of magnesium in pregnancy

Magnesium is therefore a very important mineral. In truth, there is no “proper” nutrient mineral more important than the other; they are all essential, with some exceptions represented by microelements whose role for health is not yet well defined.

We have already mentioned the main functions of magnesium, but not the specific (or assumed) ones in pregnancy which, moreover, are often confused with each other. It is in fact a common misconception to mix the prevention of deficiency effects with what should be the effects of an increase in intake beyond the norm.

Since this is a fairly complex topic, we will propose a practical example below to make it easier to understand:

  • Magnesium has an alkalizing effect. It is an absolute feature; magnesium has an alkalizing power whether it is introduced in small or large quantities. Then, the healthy body is able to manage nutritional excesses and defects by regulating absorption and excretion, taking it from the bones or eliminating it in the urine. The alkalizing characteristic of magnesium is however objective.
  • Magnesium deficiency can be responsible for dangerous uterine contractions. However, this does not mean that increasing the magnesium intake BEYOND the recommended ration (the normal one, which any pregnant woman should respect) reduces the risk of uterine contractions, premature birth , etc.

To avoid confusing readers too much, we will limit ourselves to specifying that:

if the intake of magnesium with the diet is already normal, the preventive functions of a possible nutritional increase are reduced to almost zero. On the other hand, if the pregnant woman’s nutritional regime is dangerously at risk of magnesium deficiency, increasing its intake is undoubtedly the most suitable choice.

Causes of magnesium deficiency in pregnancy

During pregnancy, the intake of magnesium with food may not fully cover the mother’s needs. We emphasize “of the mother”, not of the fetus, as this physiological condition always favors the coverage of the child’s needs. He therefore risks being left without only the mother, not the child. However, any mineral deficiency, affecting the muscles (striated but also smooth), can jeopardize the outcome of pregnancy due to possible unwanted uterine contractions.

Possible reasons for magnesium deficiency, often co-existing, are:

  • Increased need due to pregnancy
  • Insufficient dietary intake (also due to nausea)
  • Vomiting, due to nausea, which causes the expulsion of magnesium from the body
  • Excessive sweating .

Effects of increased magnesium, if deficient, in pregnancy

Let us now summarize the effects of increasing magnesium during pregnancy (especially when the diet is potentially deficient in the mineral):

  • Ensures proper fetal growth
  • Prevents low birth weight
  • Reduces the risk of preeclampsia or gestosis
  • Regulates uterine contractions
  • Reduces the risk of premature birth
  • Reduces the risk of pregnancy hypertension
  • Prevents muscle cramps
  • Reduces the feeling of nausea and vomiting
  • It reduces the feeling of tiredness , weakness, irritability and insomnia .


What is the point of supplementing a balanced diet with magnesium ?

To nothing. According to an April 3, 2014 study called “Magnesium supplementation in pregnancy” which reviewed the “Cochrane Pregnancy and Childbirth Group’s Trials Register” (March 31, 2013), there is not enough significant evidence showing the benefits of dietary supplementation of magnesium in pregnancy.



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