Supplement use in pregnancy and breastfeeding

Why the decision belongs to a clinician

There are three reasons, and none is a formality:

• Total intake changes. Most people take a prenatal vitamin in this period. Add a second supplement and the total of certain ingredients rises without anyone noticing. The person who can see that overlap is the clinician reviewing both.
• Safety data are limited. For ethical reasons, the safety of supplement ingredients in pregnancy often cannot be studied in controlled trials. Even for magnesium oxide, clinical references note that safety has not been established and that there are no controlled data in human pregnancy.
• Not every symptom is due to pregnancy. Tiredness, cramps and sleep problems in this period can also relate to anaemia, thyroid disorders and pregnancy complications. Each needs its own assessment.

Magnesium: intake and evidence

Recommended magnesium intakes in pregnancy are reported by sources in the region of 350–360 mg/day, with some giving a wider range. The nutrient reference value used for comparison on labels is 375 mg of elemental magnesium. There is also a separate upper level defined for magnesium from supplements, which does not include magnesium obtained from food — so “from food” and “from supplements” are not treated the same.

On leg cramps in pregnancy: a Cochrane review graded the certainty of evidence for treatments as low or very low. The trials were poorly designed and too small to answer the question, and outcomes were measured in different, incomparable ways, so no meta-analysis was possible. Some sources state that oral magnesium does not appear to help leg cramps in pregnancy. More in Magnesium and muscle cramps.

The same review could not assess safety either, because adverse outcomes other than side effects were not reported.

Breastfeeding

Here the data are thinner still. What is available indicates that urinary magnesium excretion falls during breastfeeding and that maternal magnesium supplementation is not expected to affect the infant’s serum magnesium. That is a brief note; there is no intake recommendation specific to breastfeeding. Again, the decision belongs to a clinician.

Caffeine

Magvela’s RISE capsule contains caffeine. Caffeine intake is restricted during pregnancy and breastfeeding, and the limit is discussed in terms of total intake — coffee, tea, cola and supplements counted together. Tell your clinician clearly that the product contains caffeine.

What to tell your clinician

• The brand and composition of your prenatal vitamin.
• The full ingredient list and amounts of the product you are considering — a photo of the label is the most practical way.
• Your daily caffeine intake: how many cups of coffee, how many cups of tea.
• All medicines you take, particularly iron, thyroid medication and stomach medicines — there may be timing conflicts with magnesium. See Magnesium and drug interactions.

When it is urgent

One-sided persistent leg pain; swelling or redness in the calf; severe headache; visual changes; upper abdominal pain; sudden swelling; or reduced fetal movement are findings that need prompt assessment.

Frequently asked

The questions most often searched on this topic, answered as they are.

Related reading

• Magnesium and drug interactions — the timing table
• Magnesium and muscle cramps — what the Cochrane review concluded
• Magnesium intake and deficiency — why intake falls short, and food sources
• All guides