Why no magnesium during pregnancy?

Magnesium during pregnancy

There is no general prohibition on magnesium during pregnancy. Magnesium is an essential mineral and is taken in quite normally through the diet during this special phase of life, too. At the same time, a pregnancy does not automatically mean that additional magnesium should be taken in the form of capsules or other food supplements.^1,2,7

During pregnancy, numerous changes take place in the mother’s body, while at the same time the unborn child develops in the womb. A good supply of nutrients is therefore important for mother and child. The German Federal Institute for Risk Assessment (BfR) points out that a varied and wholesome diet can cover the requirement for most vitamins and minerals during pregnancy as well. Pregnant women should not take food supplements on their own without medical recommendation.³

Whether and how a magnesium supplement is used should therefore be discussed individually with a female doctor, gynaecologist or midwife. General information on the mineral and on our magnesium capsules and magnesium powder can be found on our magnesium page.

Why is it said that you should not take magnesium during pregnancy?

Behind this statement lies above all the idea that magnesium could relax the musculature and thereby, towards the end of pregnancy, also affect the uterus and labour activity.

What is correct: according to the authorised EU health claim, magnesium contributes to normal muscle function.⁵ Because the uterus, too, consists of musculature, the assumption arose that additionally taken magnesium could delay the birth.

From this general function of magnesium, however, it cannot be concluded that orally taken magnesium inhibits labour or fundamentally has to be stopped at a particular point in time. Two different questions are also often mixed up here:

• May magnesium be taken in during pregnancy? Yes. Magnesium is a normal component of the diet.
• Should every pregnant woman additionally take a magnesium supplement? No. According to the current DGE assessment, a higher intake does not demonstrably bring a general advantage for pregnant women; Cochrane, too, sees no sufficient high-quality evidence of a general benefit of routine supplementation.^2,7

Can magnesium inhibit labour?

The concern that orally taken magnesium could relevantly weaken natural labour activity at the end of pregnancy is not sufficiently scientifically proven.

A study by Meier et al. examined 40 pairs of healthy women with singleton pregnancies. One group had taken oral magnesium over at least four weeks up to the birth. The first and second stages of labour were numerically longer in this group, but the differences compared with the control group were not statistically significant. There was also no significant difference in the maximum oxytocin required.⁶

The study was, however, small and not randomised. From it, therefore, neither can it be concluded that every woman should continue magnesium up to the birth, nor that magnesium fundamentally has to be stopped before the birth.

Does magnesium have to be stopped before the birth?

A generally applicable rule such as “No more magnesium from the 36th week of pregnancy” or “Magnesium must be stopped four weeks before the birth” cannot be derived from the available study data.⁶

Anyone already using a magnesium supplement should therefore neither stop taking it on their own solely because of a particular week of pregnancy nor automatically continue it up to the birth. What is decisive is the reason for taking it, the dosage, further supplements or medicines and the individual situation.

Particularly with medicines or several food supplements, interactions and dosing intervals can additionally play a role. What to consider here is explained in detail in our guide What should not be taken together with magnesium?.

How high is the magnesium intake during pregnancy?

The DGE currently states an estimated value for an adequate magnesium intake of 300 mg per day for pregnant women. The same value applies to adult women from the age of 19 and to breastfeeding women.¹

Group	DGE estimated value
Adult women from age 19	300 mg/day
Pregnant women	300 mg/day
Breastfeeding women	300 mg/day

The DGE explicitly explains that, because of the insufficient data and inconsistent study results, it currently cannot be assessed whether a higher magnesium intake brings pregnant women an advantage. That is why no higher estimated value is set for pregnant women.²

Older figures according to which, for example, there is an additional requirement of about 10 mg per day in pregnancy or 310 mg is necessary therefore do not correspond to the current DGE assessment. The general question of daily requirement, intake and dosage is deliberately dealt with in more detail in our separate guide: How much magnesium per day?.

Does magnesium have to be additionally taken during pregnancy?

Not automatically. The BfR emphasises that a varied and wholesome diet can cover the requirement for most vitamins and minerals during pregnancy, too. At the same time, it recommends that pregnant women be particularly cautious with food supplements and not take them on their own without medical recommendation.³

The scientific data, too, does not argue for recommending magnesium to all pregnant women across the board: the Cochrane review found no sufficient high-quality evidence that routine magnesium supplementation during pregnancy is generally beneficial.⁷ Whether additional support of the magnesium supply is sensible in an individual case therefore belongs in the advice given by a female doctor, gynaecologist or midwife.

What role does magnesium play in the body?

Magnesium fulfils various normal bodily functions. According to the health claims authorised in the EU:

• magnesium contributes to normal muscle function,
• magnesium contributes to the normal function of the nervous system,
• magnesium contributes to the reduction of tiredness and fatigue,
• magnesium contributes to the maintenance of normal bones,
• and magnesium has a role in the process of cell division.⁵

These statements refer to the general functions of the mineral in the body. They do not mean that the additional intake of a magnesium supplement during pregnancy improves the development of the foetus, the growth of the child or particular bodily functions of the baby.

Statements such as “Magnesium supports the growth of the foetus” or “Magnesium promotes the bone development of the unborn child” would therefore go beyond the authorised health claims and are deliberately not made here.

Can magnesium be taken in through the diet?

Yes. Natural sources of magnesium are, for example, kernels and seeds, nuts, wholegrain products, pulses and green leafy vegetables; foods such as bananas also contribute to the intake.¹

Which foods are particularly rich in magnesium and how high the respective magnesium content is, we show in detail in the article Where is the most magnesium found?. Many foods contain several minerals at the same time. What role magnesium and potassium play here, and in which foods both occur, we therefore deal with in a separate article.

What should be considered with magnesium supplements during pregnancy?

Anyone using a magnesium supplement during pregnancy should look at the overall supply. Pregnancy preparations can already contain various vitamins and minerals. Additional capsules or other single-nutrient products should therefore not be combined without a look at the amounts contained. The BfR fundamentally advises pregnant women against taking food supplements on their own without medical recommendation.³

Magnesium and iron: Iron, too, can be a topic during pregnancy. With additional iron therapy, the simultaneous intake of certain magnesium preparations should be considered. The patient information leaflet for Magnesium 100 mg JENAPHARM explicitly notes that the absorption of iron can be impaired when magnesium is taken at the same time.⁸ How magnesium should be combined with iron, other minerals and medicines is therefore not dealt with further here, but in the guide What should not be taken together with magnesium?.

Can too much magnesium cause diarrhoea?

Yes. An increased additional magnesium intake from food supplements can lead to mild diarrhoea. The BfR recommends a maximum daily amount of 250 mg of additional magnesium for food supplements and explicitly points out that this value refers to additionally ingested magnesium from food supplements or fortified foods.⁴

How different amounts are to be classified in general is therefore reserved for the article: How much magnesium per day?.

What applies with kidney dysfunction?

With existing conditions, additional intake should be clarified particularly carefully with a doctor. For the medicine Magnesium 100 mg JENAPHARM, severe kidney dysfunction is explicitly listed as a contraindication. With mild to moderate kidney dysfunction, it should only be taken under medical supervision.⁸ These details refer specifically to this medicine and should not be transferred across the board to every magnesium food supplement.

Which magnesium compound is suitable?

Magnesium supplements can contain different magnesium compounds. Which form, amount or quality of a preparation is suitable in an individual case should not be decided during pregnancy solely on the basis of general statements on the internet.

Magnesium stearate, too, must not be confused with a magnesium supplement. What lies behind this substance is explained in the article Magnesium stearate: a bad reputation without cause?.

What should be considered with a suspected magnesium deficiency during pregnancy?

Individual complaints such as calf cramps, tiredness, dizziness or abdominal discomfort can have many different causes during pregnancy. They are therefore no reliable proof of a magnesium deficiency in pregnancy.

A single magnesium level in the blood, too, does not allow a simple assessment of the overall magnesium supply. The DGE points out that there is currently no suitable biomarker for determining magnesium status, among other reasons because magnesium occurs predominantly inside the cells.²

Anyone who notices symptoms or suspects a deficiency should therefore not self-diagnose and not change the dosage of a preparation on their own. The causes and possible signs of a deficiency are a separate search intent and are dealt with in detail in our guide: How do you recognise a magnesium deficiency?.

What does magnesium have to do with pre-eclampsia?

Pre-eclampsia, colloquially sometimes also called “pregnancy poisoning”, is a medical pregnancy complication. It can be accompanied, among other things, by elevated blood pressure and belongs in medical treatment.

The WHO recommends magnesium sulfate to prevent eclampsia in women with severe pre-eclampsia as well as to treat eclampsia. This is a medically supervised intravenous or intramuscular therapy.⁹

That is something fundamentally different from the independent intake of a freely available magnesium supplement. From the medical use of magnesium sulfate, therefore, no recommendation for magnesium food supplements in pregnancy can be derived.

Why is the question “Why no magnesium during pregnancy?” misleading?

Because it assumes a fundamental prohibition that does not exist in this form. Four points are decisive:

• Magnesium is a normal component of the diet during pregnancy, too.
• The DGE currently states an estimated value of 300 mg per day for pregnant women and sees no proven general additional requirement.^1,2
• Additional magnesium supplementation is not automatically needed by every pregnant woman; high-quality evidence for a general benefit of routine supplementation is lacking.⁷
• There is no sufficiently proven general rule according to which oral magnesium must be stopped from a particular week of pregnancy.⁶

Instead of “You must not take magnesium during pregnancy” it is therefore more accurate to say: whether a magnesium supplement is sensible during pregnancy and how long it should be taken must be assessed individually.

Conclusion

Magnesium is not fundamentally prohibited during pregnancy. The widespread assumption that oral magnesium supplements must be stopped before the birth because they would otherwise inhibit labour cannot be derived as a general rule from the available study data.⁶

At the same time, there is no reason to take magnesium as a precaution because of this. The DGE currently states an estimated value of 300 mg per day for pregnant women and sees no proven general additional requirement compared with non-pregnant women.^1,2 A Cochrane review also found no sufficient high-quality evidence of a general benefit of routine magnesium supplementation during pregnancy.⁷

Whether a magnesium supplement is sensible in an individual case, which dosage comes into question and whether an existing intake should be continued up to the birth therefore belongs in the advice given by a female doctor, gynaecologist or midwife.

Frequently asked questions about magnesium during pregnancy

Is magnesium prohibited during pregnancy?

No. Magnesium is a component of the normal diet and is not fundamentally prohibited during pregnancy. Whether an additional magnesium supplement is sensible should be clarified individually with a professional.

Do you have to stop magnesium during pregnancy?

Not fundamentally. A small study found no significant lengthening of labour or a significantly higher oxytocin requirement with continued oral magnesium intake up to the birth. Because of the limited study size, however, no general recommendation to continue can be derived from it either.

From which week of pregnancy should you stop magnesium?

A scientifically proven general week of pregnancy from which orally taken magnesium must be stopped cannot be derived from the available data. Continued intake should be coordinated individually with the professional providing care.

Do pregnant women need more magnesium?

According to the current assessment of the DGE, there are no sufficient indications of a general additional requirement. For pregnant women, therefore, the same estimated value of 300 mg of magnesium per day currently applies as for non-pregnant adult women.

Can too much magnesium cause diarrhoea during pregnancy?

An increased additional magnesium intake via food supplements can cause diarrhoea. The BfR generally recommends a maximum daily amount of 250 mg of additional magnesium for food supplements. This value is not a specific dosage recommendation for pregnant women.

Sources

1. German Nutrition Society (DGE): Magnesium – Reference Values – Documents the current estimated values of 300 mg/day for adult women, pregnant women and breastfeeding women, as well as natural sources of magnesium.
2. German Nutrition Society (DGE): Selected Questions and Answers on Magnesium – Documents that no higher estimated value is currently set for pregnant women and that no suitable biomarker for the simple determination of magnesium status is available.
3. German Federal Institute for Risk Assessment (BfR): Folic acid and co. – Do pregnant women have to supplement their diet? – The BfR explains that a varied diet can cover the requirement for most vitamins and minerals, and advises pregnant women not to take food supplements on their own without medical recommendation.
4. German Federal Institute for Risk Assessment (BfR): Maximum daily amount for magnesium in food supplements – Documents the general recommendation of a maximum of 250 mg of additional magnesium per day from food supplements and that higher additional intakes can cause diarrhoea.
5. European Commission: EU Register of Nutrition and Health Claims – Documents the authorised magnesium claims, among others on muscle function, nervous system, tiredness, bones and cell division. The claims apply under the respective prescribed conditions of use.
6. Meier B., Huch R., Zimmermann R., von Mandach U. (2005): Does continuing oral magnesium supplementation until delivery affect labor and puerperium outcome? – The study with 40 matched pairs of women found no statistically significant lengthening of the stages of labour and no significantly higher oxytocin requirement with continued oral magnesium intake up to the birth. Because of the study design and the small sample, it is only of limited generalisability.
7. Makrides M., Crosby D. D., Shepherd E., Crowther C. A. (2014): Magnesium supplementation in pregnancy. Cochrane Database of Systematic Reviews – The review covers ten studies with a total of 9,090 women and concludes that there is not enough high-quality evidence of a general benefit of magnesium supplementation during pregnancy.
8. PatientenInfo-Service: Magnesium 100 mg JENAPHARM – patient information leaflet – Documents, for this specific medicine, the possible impairment of iron absorption, the contraindication with severe kidney dysfunction and notes on high dosage and soft stools or diarrhoea.
9. World Health Organization (WHO): Recommendations for Prevention and Treatment of Pre-eclampsia and Eclampsia – The WHO recommends magnesium sulfate to prevent eclampsia in severe pre-eclampsia and to treat eclampsia. This recommendation concerns a medically supervised therapy and not ordinary magnesium food supplements.