Magnesium for Pregnant Women: What’s an Adequate Intake?

Magnesium is a metal vital for plant, animal, and human life. Magnesium is a key nutrient for hundreds of chemical reactions within the body. However, this versatile nutrient is especially important for pregnant women. Keep reading to learn what are benefits of magnesium supplementation and how to ensure adequate intake during your pregnancy.

Magnesium’s importance in pregnancy

Magnesium is the most common metal ion found in the body and is an essential nutrient for more than 600 bodily chemical reactions. Magnesium plays a vital role in the following:

  • Fetal bone development
  • Cardiac function of mother and baby
  • Seizure prevention
  • Uterine contraction
  • Protein synthesis
  • Blood glucose regulation
  • Vascular tone regulation and much more

Determining magnesium levels

Interestingly, at least 50% of the body’s magnesium is found in the bones and only 1% in blood serum. However, serum magnesium is the primary means for measuring adequate magnesium levels. Since serum levels are low in correlation to total body magnesium levels, many medical professionals are questioning the effectiveness of this measuring tool.

Unquestionably, total body magnesium levels are difficult to assess, and no single method of evaluation is adequate at this time. Therefore, providers rely on blood levels and symptom evaluations to determine if a pregnant woman is suffering from low magnesium (hypomagnesemia).

Hypomagnesemia statistics

According to the World Health Organization (WHO), magnesium deficiencies are prevalent in both developed and underdeveloped countries. Many equate this deficiency to a decreased intake of magnesium-rich foods, overprocessed foods, and changes in produce cultivation practices, which lower mineral content.

Surprisingly, studies show that the magnesium content of certain produce has decreased by 20–27% since 1968. According to an analysis by the National Health and Nutrition Examination Survey (NHANES), 65% of women ages 19–30 have an inadequate magnesium intake.

As indicated above, the majority of women of childbearing age are not meeting the United States recommended daily allowance (RDA). Women in this season of life need 350–400 mg of magnesium daily. Secondly, women who are breastfeeding also need to be aware of their diet. Lactating women need approximately 310–360 mg of magnesium a day.


How to get enough magnesium

Though most women are deficient in magnesium, it is not difficult to change this statistic. Magnesium is naturally found in many foods. A supplement is often not necessary, but a trip to the local farmer’s market or grocery store is a good idea. Here are some magnesium-rich foods to pick up while you are grocery shopping:

Green leafy vegetablesSpinach, swiss chard, arugula
SeedsPumpkin and chia
NutsAlmonds, cashews, peanut
LegumesBlack beans, edamame
Whole grainsShredded wheat, bran flakes

In general, foods with high dietary fiber usually contain significant amounts of magnesium. When eating breads and cereal, choose the whole grain options. The refining of grain often removes the nutrient-rich fiber and much of the naturally occurring magnesium.

Reasons for prescribing magnesium

Magnesium is vital for a significant number of enzymatic reactions in the body. Low magnesium levels are often not symptomatic. Yet, hypomagnesemia in pregnancy might be associated with several symptoms.

Support uterine function

Preterm labor is the leading cause of perinatal deaths. Magnesium plays a significant role in muscle contractions and relaxation. The uterus is a muscle. Therefore, it is thought that low magnesium levels may contribute to early contraction of the uterus and preterm labor. Increasing dietary intake of magnesium supports proper muscular and uterine function.

Decrease risk of seizures

Preeclampsia is diagnosed when a pregnant woman has high blood pressure levels and protein in the urine. Providers are prescribing magnesium to reduce the seizure threshold does to its ability to dilate vessels. Magnesium solutions are also used intravenously to prevent seizures in preeclampsia cases. This safe treatment decreases the risk of eclampsia and maternal deaths by 50%.


Reduce insulin resistance

With rates of obesity on the rise, the prevalence of gestational diabetes mellitus (GDM) will likely follow. Magnesium impacts insulin-signaling pathways. Low magnesium intake has been shown to negatively affect insulin sensitivity and blood glucose levels. Therefore, increasing magnesium is given in GDM cases to reduce insulin resistance.

Promote adequate fetal nutrition

Magnesium, along with other key nutrients, promotes fetal nutrition. Obviously, maternal diet has a great impact on a baby's birth weight. However, the answer is not always increasing the amount of food but rather increasing the amount of nutrient-rich foods.

Symptoms of low magnesium

Magnesium plays a vital role in many chemical reactions. A deficit of magnesium affects many bodily functions. Therefore, determining if low magnesium is the cause of symptoms is difficult. Yet, there are some early and late signs of low magnesium levels.

Early signs of hypomagnesemia

Since most of the body's magnesium is found in the bone, serum magnesium levels are slowly depleted for up to 4 months before the noticing of signs or symptoms. Some early signs of magnesium deficiency are as follows:

  • Loss of appetite
  • Nausea
  • Vomiting
  • Fatigue
  • Weakness

Late signs of hypomagnesemia


Because magnesium levels are challenging to assess, the deficiency may become moderate to severe before lab values indicate a problem. Knowing the signs of hypomagnesemia helps promote self-advocacy. The following are late symptoms of low magnesium levels:

  • Electrolyte imbalances
  • Numbness or tingling
  • Muscle cramps
  • Seizures
  • Irregular heart rhythm
  • Kidney stones

Benefits and risks of magnesium

The benefits of increasing magnesium-rich foods are great. Supplements are usually not necessary. Eating a diet rich in dietary fiber promotes adequate magnesium intake. However, under your provider’s watchful eye, a magnesium supplement is a safe preventive treatment option for pregnant women.

High doses of magnesium sourced from supplements or medications, like antacids and laxatives, can have negative effects, such as:

  • Nausea
  • Abdominal cramping
  • Diarrhea
  • Medication interactions
  • Magnesium toxicity in unborn babies

Magnesium is the most commonly found metal ion in our bodies and is important for so many bodily functions. The majority of women of childbearing age are deficient in magnesium. Pregnant women are at great risk of being negatively impacted by hypomagnesemia. However, improving your diet is often all that is needed. Consuming foods rich in dietary fiber improves magnesium intake. Remember, talk with your provider anytime you need medication, including antacids, laxatives, or magnesium supplements.

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