Can you take magnesium while pregnant?

Magnesium is an incredibly important mineral for your body.
Written by
Bailey Petts
Reviewed by
Last updated on
June 3, 2024
min read
Can You Take Magnesium While Pregnant? | Kin Fertility
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Your body is amazing — it's a temple, truly. That's why it's good to be aware of all the vital ingredients that make you a happy and healthy mum.

One of those vital nutrients is magnesium. While it can be obtained via food, you're probably familiar with magnesium supplements, which are often taken to assist with things like sleep quality, muscle spasms and migraines.

But, can you take a magnesium supplement while pregnant? Here's what you need to know first.

Benefits of magnesium for pregnant people

Magnesium is an incredibly important mineral for your body and many pregnant women worry whether they're getting enough or not. When taken during pregnancy, it can help with:

  • Migraines
  • Anxiety
  • Leg cramps
  • Constipation
  • Gestational hypertension
  • Controlling blood pressure such as decreasing the risk of high blood pressure
  • Reducing pregnancy complications such as preterm birth

It can also affect your baby's growth so it's a pretty important mineral to know about, especially when you're pregnant.

While your magnesium intake can usually be managed through what you eat and drink, supplementation during pregnancy might be considered as your changing hormone levels can affect your magnesium levels.

What is magnesium?

Magnesium (or Mg) is a mineral required for brain and body function. Both the mother and baby need this mineral to have healthy growth during and after pregnancy.

It is one of the 7 macrominerals that you need to maintain in your body daily [1]. Iron and zinc are important, too, however, the amount of magnesium you need is higher.

During pregnancy, your body changes constantly and you need to make sure you're consuming the right amount of magnesium to support optimum body functions for a reduced risk of magnesium deficiency.

Does magnesium affect the baby?

Your baby consumes everything that you do, whether this is dietary supplements, food, drink or other lifestyle factors such as smoking.

So, of course, a magnesium supplement will affect the baby — more on that later.

What does magnesium do?

Magnesium supports energy, nerve function, bone health and muscles. It also plays an important role in your pregnancy outcome and carrying your baby.

Magnesium during pregnancy helps:

  • Maintain your diastolic blood pressure
  • Improves pregnancy-induced leg cramps and muscle cramps
  • Reduce the risk of preterm birth and preterm labour [2]
  • Reduce restriction of foetal growth [3]
  • Increase birth weight.

A magnesium deficiency can be connected to restricted foetal growth due to high blood pressure, so to avoid poor pregnancy outcomes, making sure that you're getting everything your body needs whilst pregnant is very important [4].

You want your baby's weight gain to be gradual and healthy, and magnesium is a key mineral required for this.

Various studies have shown a significant difference when mothers take magnesium during pregnancy.

Magnesium supplements provide a healthy top-up of the mineral, which encourages the healthy growth of your baby and reduces pregnancy complications.

It's good to look at it as something your body needs and, when your body is already working overtime supporting your health and your baby's, a daily magnesium supplement can decrease the chances of deficiency, improve foetal growth and increase birth weight.

Can you take magnesium when pregnant?

Although there are studies that state there's a reduced risk in preterm labour or preterm birth, magnesium supplementation during pregnancy might not make a significant difference.

An Mg deficiency is closely connected to dietary factors, so if you're experiencing magnesium deficiency during pregnancy, supplementation is often advised.

Due to your rapidly changing hormones, which can make pregnancy all the more chaotic, especially in your first trimester, you are likely to experience morning sickness or sickness all day.

As your fluctuating hormone levels alter your magnesium levels, supplementation during pregnancy can actually improve or reduce your morning sickness symptoms [5].

Similarly, you might experience leg cramps due to fluctuating magnesium levels and this might be a sign to up your magnesium dose.

Of course, with any changes in supplementation during pregnancy, consult with your doctor first.

They'll be able to confirm whether you need Mg supplementation during pregnancy or not — it might just be something you need after you give birth due to the likelihood of losing precious minerals from your body.

Should you avoid magnesium in the last trimester?

While magnesium supplementation is generally harmless, it is worth flagging that some antacids, which you might take for pregnancy-related indigestion and heartburn, can contain magnesium (magnesium oxide), which in some cases, could complicate uterine contractions during labour.

And, it also uses magnesium amino acid chelate, which is bioavailable (making it easier for your body to absorb and use) while also being gentle on the stomach.

How much magnesium is safe during pregnancy?

During pregnancy, the recommended daily dose of magnesium is 350-360 milligrams to avoid pregnancy complications [6]. 500mg is considered too much and could cause magnesium toxicity.

Don't forget that you also get this essential mineral from food and you don't need your entire daily dose to come solely from a supplement.

Ensure you're eating a healthy amount of green leafy vegetables, seeds, nuts and beans per day so that your supplement is merely a 'top up' of magnesium.

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

Your magnesium levels can be maintained through your diet but your fluctuating hormones during pregnancy can impact your magnesium levels.

The best magnesium supplement depends on dietary reference intakes. For example, if you have a highly nutritious diet with less change of nutrient deficiencies, then you will be able to take a smaller dose.

It's best to consult with your doctor regarding the amount of magnesium that you need.

How do you know if you're deficient in magnesium when pregnant?

Although quite rare, signs to look out for with magnesium deficiency are [7]:

  • Nausea
  • Loss of appetite
  • Insomnia
  • Weakness
  • Irregular heartbeat

A magnesium deficiency isn't an automatic experience for pregnant people, so don't worry too much.

If you have poor nutrition, high blood pressure and are over the optimum child bearing age, then there is an increased risk in magnesium deficiency.

Mg supplementation just makes it easier to maintain the right levels for you and your baby.

Magnesium and gestational diabetes

Some evidence has indicated that a magnesium deficiency could elevate the risk of gestational diabetes mellitus, thanks to the effects on insulin sensitivity and glucose control [8].

A study from 2020 found that magnesium supplementation during pregnancy can actually reduce "maternal serum glucose" (blood glucose levels), including the hard-to-control fasting glucose [9].

Research from 2019 suggests that magnesium during pregnancy can positively impact those who are at a high risk of gestational diabetes due to their gestational age and could be helpful in preventing complications and improving pregnancy outcomes associated with gestational diabetes [8].

What kind of magnesium should you take during pregnancy?

For magnesium supplementation, there are a few types of magnesium.

Magnesium sulfate

A combination of sulfur, oxygen and magnesium (think Epsom salt) that can soothe your muscle tension.

Magnesium amino acid chelate

It is best for bioavailability and being gentle on the stomach.

Magnesium citrate (Mg citrate)

Bound with citric acid, this type of magnesium is found in citrus fruits and is the most common form for magnesium supplementation.

Magnesium citrate is absorbed easily through your digestive tract.

Magnesium oxide (Mg oxide)

This is oxygen and magnesium together, typically in powder form. It's more of a temporary fix for things such as heartburn, migraines or constipation [10].

You want to take a type of magnesium that is easily absorbed through your digestive tract and has reduced side effects. For this reason, magnesium amino acid chelate works wonders.

Can you use magnesium oil or magnesium spray when pregnant?

Magnesium oil is perfectly safe to use externally when pregnant and many pregnant people carry this around with them wherever they go!

There is no evidence that using magnesium spray transdermally (on your skin) has negative side effects for you or your baby.

If you've never used a magnesium spray or oil before, it is applied topically to help reduce painful cramps, which can be common during pregnancy.

By using a topical solution, you're able to target cramping without consuming oral supplements that impact your magnesium levels.

Magnesium for leg cramps in pregnancy

Leg cramps can be incredibly painful and are often a common experience for pregnant people. Thankfully, there are a few things you can try to help relieve the uncomfortable tension in your muscles.

Magnesium sulfate — in the form of Epsom bath salts — can help reduce muscle aches and leg cramps. And, taking a warm bath is also a pleasant experience that can help relax the body.

However, it should be noted that there is limited scientific evidence to suggest that magnesium supplementation can resolve your leg cramps fully [11].

Your best bet at reducing cramps is to keep active and consume a nourishing diet filled with nutrients and minerals like calcium and magnesium.

Observational studies show that magnesium citrate and magnesium sulfate also help to decrease swelling and tired muscles but whether or not it is a placebo effect hasn't been ruled out [12].

Anecdotally speaking, magnesium supplementation for leg cramps is loved by many people so it could be worth giving it a go for yourself.

Be sure to consult your doctor if you're experiencing intense pain or consistent cramps.

Magnesium for sleep in pregnancy

Another joy of pregnancy is restless legs syndrome. It can really affect your sleep, which is something you need a lot of when you're growing another human.

Magnesium supplementation can help you relax, feel sleep and reduce the feelings of restless legs, in turn, helping you get better sleep. Be sure to consult your doctor about supplementing magnesium during pregnancy.

Magnesium during pregnancy: The takeaway

Magnesium supplementation during pregnancy can help ensure you're meeting your mineral requirements and that your baby isn't leaving you without any magnesium of your own.

Prenatal nourishment is key and including magnesium supplementation in your daily routine may help support your baby's growth and development whilst making your pregnancy all the more comfortable.

After selling out twice, you can rest assured that our Prenatal Vitamins are well-loved and can help put your mind and body at ease.

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