Can I Take a Magnesium Supplement During Pregnancy?

We recently discussed the potential benefits of magnesium supplementation in a bit of detail. What we found was that most people should be able to get the magnesium they need through a healthy and balanced diet. We also found that diet is the superior source of vitamin and mineral intake due to the better bioavailability and the better chance for a balanced uptake of nutrients, since taking single nutrients can sometimes cause nutritional imbalances (nutrients interact, they don’t act alone.).

However, there are some populations that may benefit from taking a magnesium supplement. One of those is pregnant women. Let’s explore that a little. 

Are pregnant women getting enough magnesium?

For what reasons would a pregnant woman take a magnesium supplement?

Magnesium may promote better sleep

Magnesium may help with joint and muscular discomfort

Magnesium may reduce risks and symptoms related with preeclampsia

Summary / TLDR

Are pregnant women getting enough magnesium?

In theory, even if you are pregnant, diet should provide all the magnesium you need. 

The recommended daily intake of magnesium for adult women is 310-320 mg, while the recommended intake for pregnant women is slightly higher at 350 mg. Prenatal vitamins typically do contain magnesium. I’m sure it varies but I’ve seen around 10% of daily allowance seems pretty common. Again, if you’re eating a relatively balanced diet, you should already be getting enough magnesium and if you are taking a regular prenatal vitamin, that added magnesium should be plenty to fill any gaps. 

And yet, we do know that there is a decent prevalence of inadequate magnesium intake (really of most nutrients) in America. It’s difficult to get solid numbers on this, but a reasonably reliable one is that as many as 60% of Americans are not getting enough magnesium through their diets according to an analysis of their food consumption for two days. I want to highlight that we’re talking inadequate intake here, not deficiency, which is more severe.

As for pregnant women, there have been a few measurements of magnesium serum level to try to determine the level of deficiency in this population, but it’s clear the data is severely limited. Based on a good sample size in Russia, magnesium deficiency was between 34% and 79% (depending on the serum level they were considering as marking deficiency) and a much smaller sample in Berlin found a deficiency rate of about 16%. I haven’t been able to find data like this for American women. There are others with other measurements, but all this data can really tell you is that we don’t know the level of deficiency for pregnant women (though people like to keep passing these numbers around and saying we do). It’s difficult to adequately and consistently measure magnesium levels and serum-level may not be a perfect method, but it is often the best we have.

However, based on the general population we have for America (which is not a perfect way to measure this), it is reasonable to say that a decent number of pregnant women are not getting enough magnesium. This will obviously be impacted by issues with eating at all throughout pregnancy as well as the strong tendency of women to supplement at least a prenatal vitamin during pregnancy. 

Though the most common recommendation for pregnant women is simply to take a prenatal supplement (which does contain magnesium), it wouldn’t be unusual for a doctor to recommend magnesium to a pregnant woman as well. It’s not standard practice to just recommend to every pregnant woman though. 

I know I’ve never had a doctor recommend a specific magnesium supplement, though when recommended by other healthcare professionals, my doctors have cleared the use of this additional supplement while I was pregnant. 

For what reasons might a pregnant woman take additional magnesium?

Obviously, one reason a pregnant woman may take magnesium is because they’re deficient. I’m not going to cover all the pregnancy benefits of magnesium because I mentioned them in our previous overview of magnesium. However, there are several important functions of magnesium and being deficient while pregnant is not ideal. You can expect improvements in the fetal growth and development of babies as well as several pregnancy related issues by ensuring you have adequate magnesium intake, wherever it comes from. 

Beyond truly having a magnesium deficiency, you might take an additional supplement if you are having difficulty sleeping, for back pain, or for issues related to preeclampsia. I know I’ve been recommended a few times by a variety of people to take a magnesium supplement for the first two reasons (I’ve never experienced preeclampsia, so that hasn’t been relevant to me). 

Though you may be recommended by some to take magnesium for these reasons, let’s look at what the research says about magnesium’s benefits in these areas.

Promote better sleep

There doesn’t appear to be much research specific to magnesium supplementation and sleep in pregnancy. 

It is likely that the fluctuations in several key pregnancy hormones impact sleep in negative ways, especially toward the end of pregnancy. Additionally, the psychological stress of pregnancy and, for some, becoming a new parent, can add to the difficulty in sleeping. There are also several other health issues such as disordered breathing or obesity that can become worse in pregnancy and impact sleep but also impact sleep in and of themselves.

All in all, sleep during pregnancy can be hard to come by! It’s not possible for a supplement to overcome all the various factors involved in that.

Like I said, there’s not a lot of research on the impact of magnesium on sleep during pregnancy. I could find plenty of people and organizations online saying it helped, but next to no research. I even told you it seemed to help me, personally. That’s not exactly solid evidence though. 

The best thing we can do in this situation is look at the evidence for the impact of magnesium supplementation in the general population. This isn’t the best, as the general population isn’t always generalizable to unique populations like pregnant women. However, it’s all we’ve got at this point. 

Take the findings with a grain of salt, but I don’t think it’s unreasonable to assume at least some of the benefits seen in the general population would carry over to pregnant women, given the basic biology and chemistry of how magnesium likely works to affect these benefits.

I did a whole post on magnesium and sleep, so you can go read all of that research and my conclusions there, as well as my thoughts on the best magnesium supplement for sleep!

Relieve pain and leg cramping

There’s been a few pretty well-designed studies that found improvements in leg cramping frequency and intensity when controlled based on different dose levels as well as a placebo group.

There’s been a decent number of studies on leg cramping in the general population as well and when compared to those with pregnant women, the effect seems more prominent for pregnant women, as in, pregnant women see more benefit from magnesium supplementation than those who are not pregnant. There’s not enough to show definitive causality, but it’s decently strong evidence. Even the evidence all taken together is not enough to be conclusive, though like I said, it does appear to be a strong possibility that it can.

It’s important to note as well that it does appear any significant benefit from supplementation would be with regular intake over more than a month, which is just generally probably true of all these points considering nutrition tends to be a long-term game.

Besides this, there has been interesting research on the effects of magnesium for pain management, particularly in neuropathic disorders. It’s unclear the level of effect and some studies show no more benefit than a placebo, but some show improvement in experience in pain. This effect is supposed to come from a physiological role magnesium plays in blocking a specific receptor related to pain.

So we know that magnesium may help with pain but it’s unclear. The most likely benefit you can expect is a reduction in leg cramping.

Reduce risk and symptoms of preeclampsia

There’s a good amount of evidence that magnesium at the least is related with pregnancy-induced hypertension. This doesn’t mean that it’s the only or most important cause, but that low magnesium is relatively likely to cause hypertension during pregnancy. On the other side, there’s growing evidence that supplementing magnesium during pregnancy can help reduce rates and severity of preeclampsia during pregnancy.

You can read the study for more details, but one study I found interesting with a not perfect but very good design found that rates and severity of preeclampsia and the outcomes related to that were better for those who had low magnesium but took 300mg magnesium a day even compared to the “control” group that had normal levels of magnesium but took 100mg of magnesium a day.  

Reviews of randomized controlled trials tend to find that results are mixed whether magnesium supplementation truly reduces risk of preeclampsia, but that the evidence reasonably support that it does.

Beyond reducing the occurrence of preeclampsia, magnesium sulfate supplementation is an established standard treatment for preeclampsia when considering the management of related symptoms, such as seizures.

All in all, it seems well supported that pregnant individuals struggling with hypertension or preeclampsia would benefit by supplementing magnesium, though this is a conversation for your doctor. I don’t know this at all, but I would imagine the available research would lead a lot of doctors to recommend it already. Who knows, though. 

Summary / TLDR

Taking in enough magnesium (as with any other nutrient) is very important for both maternal and fetal health, with even some limited evidence that magnesium intake during pregnancy could impact your child’s disease outcomes in their adulthood. Nutrition is probably more important than any of the other toxicology things we talk about on this blog, and a bit easier to see in the research as well. 

Magnesium may be particularly beneficial for those dealing with preeclampsia, as magnesium supplementation may help reduce blood pressure and risk of negative health outcomes for mother and babies in this situation.

(Obviously, talk to your doctor about making any changes to your current health routines. I am not a doctor and I do not make individual health recommendations. I’m just here to present you with the current research.)

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