Is Magnesium Safe To Take During Pregnancy?


We know there are a ton of reasons to take magnesium, but some still ask, “is magnesium safe to take during pregnancy?”.


After all, not everything that’s good for you is safe while you’re expecting. Therefore, it's perfectly reasonable to question anything you put in your body throughout your pregnancy. In fact, you should! 


Before we dive into the science behind magnesium and pregnancy, let’s cover some basics on this mineral, including why it’s more important while you’re pregnant.

Why are pregnant women more likely to develop a magnesium deficiency?

During pregnancy, you are more likely to experience not just magnesium deficiency, but all types of deficiencies. This is not necessarily because you made any changes to your diet. Rather, your needs for these vitamins and minerals have increased. You have two people you need to feed now, and your body is going into overdrive to create and sustain life within you.

And, some of the complications of pregnancy can exacerbate a magnesium deficiency. Morning sickness, for example, can present a two-fold challenge: For one, constantly vomiting can lead to deficiency, as you are purging nutrients. Two, the inability to eat prevents you from regaining these vital nutrients!

What are the benefits of magnesium during pregnancy?

Magnesium deficiency can lead to a host of problems, which we will explore later on. But, there are plenty of reasons you should supplement with magnesium during pregnancy anyway, even if you don’t show signs of a deficiency. This mineral has the ability to help with many common complaints of pregnancy, including:

  • Headaches
  • Nausea
  • Leg cramps
  • Osteoporosis
  • Delivery
  • And more!

If you want to learn more, you can check out our article on the benefits of magnesium during pregnancy!

What are the side effects of too much magnesium during pregnancy?

In reality, there are no symptoms when taking a safe amount of magnesium and drinking plenty of water. This compound is pretty easy to absorb, and tough to be harmed by. But, excess can lead to issues. 

Most reported side effects of magnesium are reported by those that took way too much (over 350mg per day). Their reported effects include nausea, vomiting, and diarrhea. 


There are also more serious side effects from too much magnesium, which can be fatal. These include irregular heartbeat, slowed breathing, confusion, low blood pressure, coma, and even death. All these can be avoided by simply taking a safe dose of magnesium. If you experience any of these side effects, visit a doctor or go to the hospital.

Evidence supporting magnesium supplementation during pregnancy

Let’s examine some of the research behind magnesium and pregnancy. There have been quite a few studies that support the use of magnesium during pregnancy. Not only is magnesium safe to take during pregnancy, it can actually improve your health in a number of ways, along with your child’s.

How magnesium effects pregnancy outcomes

According to a study from the Department of Obstetrics and Gynecology, magnesium supplementation has a positive effect on pregnancy outcomes. Specifically, the study examined how magnesium supplementation affected common complications of pregnancy, such as:

  • Intrauterine growth retardation
  • Preterm labor
  • Maternal BMI (body mass index)
  • Neonatal weight
  • Pregnancy-induced hypertension
  • Preeclampsia
  • Gestational diabetes
  • Mellitus
  • Leg cramps

This randomized, controlled trial examined three groups of 60 women. Group A was women with sufficient magnesium levels, and they were simply given a multimineral tablet once a day. 


Groups B and C were considered deficient in magnesium. Group B was given the same daily multivitamin tablet as Group A, whereas Group C was given 200 mg of magnesium daily (on top of their normal diet). The groups were examined throughout the entire pregnancy.


In just about all cases, Group C reported better pregnancy outcomes than groups A and B. They showed a much lower frequency of pregnancy complications like the ones listed above. Thus, the researchers concluded that, “Magnesium supplementation during pregnancy is likely to decrease the probability of occurrence of many complications during pregnancy.” 

Its important to note that the women supplementing with Mg showed better results than even the women who weren’t deficient in magnesium (Group A) in the first place. This goes to show that even if you are getting a healthy level of magnesium, you may want to supplement with more!

What complications can magnesium help prevent during pregnancy?

A study done by the Oxford Academic Journal of Nutritional Reviews examined the effects of magnesium deficiency during pregnancy. They looked at how magnesium affects the following disorders and complications:


  • Preterm labor/birth
  • Preeclampsia
  • Gestational Diabetes
  • Preterm labor/birth

According to the research done in this study, women with lower serum magnesium levels are more prone to preterm labor or preterm delivery. However, a more useful indicator of magnesium deficiency is the examination of red cell magnesium. 


One such study was done looking at this level in pregnant women, and it found that woman who experienced preterm labor or birth had hypomagnesemia (deficiency of magnesium in the blood).

Preeclampsia

The study also found that magnesium plays a role in preeclampsia. This is a condition defined by the National Institute of Health and Care Excellence as hypertension after 20 weeks gestation combined with proteinuria. 


The study indicates that supplementing with magnesium sulfate decreases the risk of eclampsia and maternal death by 50%.

Gestational Diabetes

This is a more rare disorder only reported in 1%-14% of pregnant women. The study examined the effects magnesium has on insulin-signaling pathways such as secretion, binding, and receptor activity. 


What is concluded was that women who supplemented with magnesium showed a significant decrease in Gestational diabetes compared to those who did not. And, it can even help those who already suffer from the condition. 


An additional study found that women with Gestational diabetes who use magnesium showed increased levels of glucose control and insulin secretion.


Overall, the findings from the studies conducted in this journal were congruent - magnesium supplementation during pregnancy is safe, and can combat a number of complications.

Can magnesium harm a fetus or cause birth defects?

There is one case where pregnant women should probably avoid magnesium supplementation. We learned previously that Mg supplementation can minimize the risk of preterm labor or birth. But, women who experience it should avoid supplementing once they are aware of the condition. This recommendation comes straight from the FDA (Food and Drug Administration).

According to the warning issued, magnesium sulfate could lead to hypocalcemia and an increased risk of osteopenia and bone fractures in newborns. The reason it can cause problems is because the baby is directly exposed to the magnesium. While the exact amount of magnesium that can result in harm to newborns is unknown, the FDA advises that supplementation cease after 5-7 days.


While magnesium does help prevent preterm labor or birth, we now know that it should not be used as a treatment for the complication, or at the very most, for no longer than 5-7 days. While Mg was previously regarded as a category A drug (no known risk of harming fetus), it is now considered a category D drug (evidence of human fetal risks).

How much magnesium should I take during pregnancy?

The amount of magnesium you need to take during pregnancy differs based on age. According to the National Institute of Health, these are the guidelines:

    • 400mg - Women between the ages of 14-18
    • 350mg - Women between the ages of 19-30
    • 360mg - Women between the ages of 31-50

Before supplementing with magnesium, talk to your doctor. Certain people with certain conditions should avoid magnesium altogether, although this is rare. Be aware of the side effects of magnesium, and stop supplementation should you experience them.

Is magnesium safe to take during pregnancy?

After examining all the relevant evidence, its overwhelmingly apparent that magnesium is safe during pregnancy. Not only that, it is necessary. If you aren’t supplementing with it, you are at heightened risk for many pregnancy complications, and you will have a less positive pregnancy.


Again, we recommend talking to your doctor to come up with a course of action. But, most magnesium supplements are safe for pregnant women. If you are looking for a magnesium supplement, you may want to consider a topical. Studies have shown that magnesium absorbs better transdermally (in our skin) than when we take it orally. 


One great option is 8 Sheep Organics Sleepy Body Lotion. This is an organic body lotion packed with magnesium chloride, among other natural, beneficial ingredients. It can help you get some much needed magnesium into your body, while helping with one of the biggest challenges of pregnancy: sleep. Thousands of happy women across the country have tried it, and it can help you too!