pregnant woman taking prenatal vitamins
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Magnesium Is Super Important For Pregnancy, But How Much Is Too Much?

When you’re pregnant, you’re probably used to popping a prenatal vitamin on the daily. And while the focus is often on folic acid, there’s another mineral that’s just as mighty—and that’s magnesium. As it turns out, this super important nutrient is pivotal during pregnancy. But sometimes, more isn’t always better, so is too much magnesium bad for pregnancy? It can be.

While a prenatal vitamin packs a pretty good nutritional punch, it doesn’t usually contain magnesium. A vital nutrient to the body, magnesium is responsible for a whole host of functions, including blood sugar levels, blood pressure, making protein, bone — even DNA, the National Institutes of Health (NIH) reported. Thing is, most people aren’t getting enough of this necessary nutrient. “In the U.S., upwards of 50% of the population is deficient in magnesium,” Dr. Renee Wellenstein, M.D., an OB/GYN, tells Romper. “This makes it an important nutrient to supplement, even during pregnancy.”

So how does magnesium promote a healthier pregnancy? “Studies have shown a benefit of supplemental magnesium in pregnancy can lower some undesired pregnancy conditions such as preeclampsia, preterm labor and low birth weight,” says Dr. Wellenstein. The recommended dietary intake (RDI) for pregnant women aged 19 and older is between 350-360 mg daily, What To Expect reported.

But how can you tell if your magnesium levels are low? Your body will let you know, advises Dr. Sharyn Lewin M.D., a gynecologic oncologist in New Jersey. “Pregnancy-related leg cramps may be due, in part, to low serum magnesium,” says Dr. Lewin. You might experience other symptoms such as “fatigue and weakness, sleep disturbances, headaches, heart palpitations, and nausea,” adds Dr. Wellenstein.


But keep in mind that pregnant women might be even more prone to lower levels of magnesium. “Magnesium deficiency can be more common during pregnancy since one of the ways magnesium is cleared from the body is through the kidneys, i.e., urine,” says Dr. Wellenstein. And since peeing a lot is just par for the pregnancy course, you might be removing even more magnesium from your body during all those trips to the bathroom.

To ensure that you’re getting enough magnesium, you can be tested to ensure that your levels are correct. “You should request a RBC Magnesium level which tests for magnesium in the red blood cells,” says Dr. Wellenstein. “This test is more accurate because when a person is deficient in magnesium, you’ll see the level is low on a RBC magnesium test.”

On the flip side, though, you want to make sure that you don’t have too much magnesium, since that can trigger some troubling results. “You might experience a loss of deep tendon reflexes, respiratory depression, or even paralysis,” says Dr. Lewin. Additional symptoms could also include anything from nausea, vomiting, and diarrhea, to muscle weakness and even breathing problems.

For the most part, you can keep your magnesium levels in check on your own. “There are many sources of magnesium including food like nuts, avocados, seeds and legumes such as black beans,” says Dr. Wellenstein. “You could also take supplementation and medications including laxatives and antacids, which are commonly taken by pregnant women.” Just be sure to speak with your OB first to find out if taking laxatives is safe during pregnancy.

Although getting all of your magnesium needs from dietary sources is ideal, you might find that supplementation is necessary. If you’re experiencing any pregnancy-related ailments, a chat with your OB can help you determine if lack of magnesium might be to blame.


Dr. Renee Wellenstein, MD, an ob/gyn

Dr. Sharyn Lewin, MD, a gynecologic oncologist in New Jersey