The most critical period for micronutrient (vitamin and minerals) in pregnancy are the early weeks, long before most women know they are pregnant!
Preconception supplementation ensures there are sufficient stores of micronutrients in your body to meet the demands of a developing foetus for these early weeks.
Continuing supplementation throughout pregnancy helps meet the physiological requirements that food may not be able to achieve.
Here are the key nutrients to look for in your prenatal multivitamin:
Some prenatal multivitamins contain different or "active" forms of vitamin B9 and folic acid. Let me clarify their differences first.
Folic acid is the synthetic form of vitamin B9, found only in supplements.
Folate refers to natural B9, found in foods and our blood.
Follinic acid is a natural form of B9. It is found in some prenatal multivitamins.
Methylenetetrahydrofolate and levomefolic acid are biologically active forms of folate, meaning they don't have to "activated" in the body to affect.
It’s important to note that there are no studies on methylenetetrahydrofolate and levomefolic acid in the prevention of neural tube defects (NTD).1 What we do know about both these “active folate’s” is that they can increase blood concertation of folate much quicker than folic acid, making them suitable quicker folate repletion.
Researchers have noted that what is most important is having plasma folate concentration higher than 16nmol/L (or red blood cell folate >906 nmol/L) to protect against NTD rather than the actual simple dose of folic acid.1
There is around ~10-22% of the European population that has a polymorphism that prevents them from effectively converting folic acid to methylenetetrahydrofolate, known as the MTHFR mutation.1 These individuals tend to have less of a response to folic acid supplementation, potentially predisposing them to NTD, lip and palate deformations, and in some instance’s miscarriage.
If you are unsure what form of folate suits you, a simple blood test to check plasma folate concentrations, homocysteine, and if indicated, screening for the MTHFR polymorphism can be helpful.
Ok, so now let's talk about why folate is essential and how much you need.
Folate assists in DNA synthesis (production of new DNA) and blood production. Insufficient intake of folate during the preconception period and the first trimester is associated with a higher risk NTD.
Research has shown that women with optimal serum folate status what better assisted reproductive outcomes.2 It is recommended that all women of reproductive age consume 600 mcg/day of folate or folic acid.
The tolerable upper intake of folic acid (synthetic) is 1mg (1000 mcg) per day. Methylenetetrahydrofolate, on the other hand, has no upper intake level, though it is more expensive.
Recommendation: Ensure your multivitamin contains 400 mcg folic acid (or activated methylenetetrahydrofolate form equivalent). Plus, be sure to include another further 200 mcg/ day folate-rich foods. Folate rich foods include green leafy vegetables, beans, and lentils.
Choline plays a pivotal role in spinal cord formation, placental function, and early brain development. As a methylating nutrient, it is arguably just as important as folic acid.
There is emerging evidence that the current recommendation of 440 mg per day is insufficient and that most pregnant women would benefit from additional choline supplementation. Up to ~1000, mg per day would be more optimal for supporting pregnancy outcomes, and that high gestational choline intake is correlated with the improved cognitive function of offspring. 3
Most multivitamins will typically contain up to 100mg per capsule of choline.
Recommendation: You will be hard-pressed to find a multi with more than 100mg of choline. You may need to supplement with additional choline or optimise your diet to meet the higher "optimal" dose closer to ~900 mg/day, as suggested in recent literature.
Dietary iodine is required for the synthesis of thyroid hormones that regulate the mother's metabolic rate and promote growth and development throughout the pregnancy. Iodine is especially critical for early foetal brain development in pregnancy, and mild to moderate deficiency may lead to neurological and cognitive impairment of the infant.4
Recommendation: The recommended daily intake for iodine for both preconception and pregnancy is 250 mcg/day. 150 mcg /day from your prenatal multivitamin plus an additional 100 mcg coming from iodine-rich food including seafood, seaweed, and fortified eggs.5
Vitamin B12 supports DNA synthesis and methylation. It promotes healthy blood production in the mother and is required for neurological function in both the mother and the infant.
Research has shown that women with optimal B12 status what better assisted reproductive outcomes.2
Vitamin B12 and folic acid should always be taken together as they both mask the deficiency of each other.1
Recommendation: The recommended daily intake (RDI) of vitamin B12 is 2.6 mcg/day. Most prenatal multivitamins contain between 100 -200 mcg per capsule, which should be more than sufficient in the absence of deficiency.
For women following a strictly plant-based diet, it is best to check your serum B12 levels and supplement with additional (usually up to 1000 mcg/day) for many months, if required. 6
Zinc is involved in up to 300 different enzymatic functions within the body. Zinc is an essential mineral for the embryogenesis (formation and development of an embryo). Make sure your levels are optimal with a simple blood test before conceiving if possible.
A low dietary intake of zinc in pregnancy is linked to preterm deliveries, and deficiency may lead to prolonged labour. 7
Recommendation: Most prenatal multi will contain close to the RDI of 11 mg per day for zinc.
Zinc competes with other minerals like iron for absorption, so if your zinc levels are low, it is the best to supplement with an additional zinc tablet. I recommend taking zinc before bed because it can be nauseating.
Zinc is very bioavailable in animal foods while plant food like nuts, seeds, and legumes contains an antinutrient called phytic acid.8 Phytic acid binds to mineral, reducing their bioavailability. Soak, activate, fermented, or sprout these plant foods to decrease the effect of phytic acid in these foods.
Your body uses iron to make hemoglobin, a substance in red blood cells that moves oxygen throughout the body. During pregnancy, the demand for iron increases to keep up with the increased demand in blood supply.
Maternal deficiency is associated with low birth weight, preterm labour, and autism. 9
The recommended daily intake of iron during pregnancy is 27 mg / day. If you are following a plant-based diet, your iron RDI is up 80% higher than the standard RDI.
Recommendation: Most good prenatal multi’s will contain ~12 mg of iron. Not all forms of iron are created equally. I suggested an iron bisglycinate or chelate for optimal absorption. Amino acid bound iron supplements (like bisglycinate and chelate) are less constipating forms of iron.
Get your healthcare practitioner to keep an eye on your hemoglobin and ferritin (storage form of iron) levels. If hemoglobin drops below 110g/L in the first trimester or 105g/L in the second and third trimester, you will need to supplement with additional iron. 6
Vitamin D supports foetal skeleton development, immune function, gene expression, and hormone secretion.
Vitamin D isn't a vitamin but is a hormone. There are recent studies suggested that it has progesterone-like activity meaning it plays an essential role in fertility and reproduction. 10
Recommendation: Supplement with 500-1000 iu daily to maintain healthy vitamin D levels. Add additional if vitamin D deficiency is present. 6
Many other vitamins and minerals should make up your prenatal multivitamin; these are just seven of them that you really should check that you are getting adequate amounts. It's always a good idea to check how many tablets are required to meet these recommended dosages, as some are once a day, and others are more.
If you are unsure, always ask your healthcare practitioner.
1. Obeid, R., Holzgreve, W. & Pietrzik, K. Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects? J. Perinat. Med. 41, (2013).
2. Gaskins, A. J. et al. Association between serum folate and vitamin B-12 and outcomes of assisted reproductive technologies. Am. J. Clin. Nutr. 102, 943–950 (2015).
3. Korsmo, H. W., Jiang, X. & Caudill, M. A. Choline: Exploring the Growing Science on Its Benefits for Moms and Babies. Nutrients 11, 1823 (2019).
4. Zhou, S. J. et al. Association Between Maternal Iodine Intake in Pregnancy and Childhood Neurodevelopment at Age 18 Months. Am. J. Epidemiol. 188, 332–338 (2019).
5. Ershow, A., Skeaff, S., Merkel, J. & Pehrsson, P. Development of Databases on Iodine in Foods and Dietary Supplements. Nutrients 10, 100 (2018).
6. Baroni, L. et al. Vegan Nutrition for Mothers and Children: Practical Tools for Healthcare Providers. Nutrients 11, 5 (2018).
7. Chaffee, B. W. & King, J. C. Effect of Zinc Supplementation on Pregnancy and Infant Outcomes: A Systematic Review: Zinc Supplementation and Pregnancy Outcomes. Paediatr. Perinat. Epidemiol. 26, 118–137 (2012).
8. Hunt, J. R. Bioavailability of iron, zinc, and other trace minerals from vegetarian diets. Am. J. Clin. Nutr. 78, 633S-639S (2003).
9. Schmidt, R. J., Tancredi, D. J., Krakowiak, P., Hansen, R. L. & Ozonoff, S. Maternal Intake of Supplemental Iron and Risk of Autism Spectrum Disorder. Am. J. Epidemiol. 180, 890–900 (2014).
10. Monastra, G., Grazia, S. D., Luca, L. D., Vittorio, S. & Unfer, V. Vitamin D: a steroid hormone with progesterone-like activity. Vitam. D 11.