A multivitamin formulated for pregnancy and the period before conception, distinguished by higher folic acid, iron and iodine and by lower preformed vitamin A. Some include DHA; most do not include enough calcium or choline to matter.
Prenatals are the one multivitamin category with a defensible evidence base, and it is narrower than the packaging implies. What is well established is folic acid before conception and in early pregnancy, iodine for fetal brain development, and iron where iron deficiency exists or is likely. Beyond that, large trials of multiple micronutrient supplements in low-income settings show modest reductions in low birthweight and small-for-gestational-age births compared with iron and folic acid alone — a genuine finding, in populations with widespread deficiency. Evidence for extra micronutrients in well-nourished women is much weaker. The one hard rule is what should not be in the bottle: preformed vitamin A above modest amounts is teratogenic.
Sold as
Tablet, Capsule, Gummy (usually iron-free), Combination pack with DHA softgel
Regulation: Sold as a dietary supplement in the US with no pre-market efficacy review, though some prenatals are marketed as prescription products. WHO recommends daily iron and folic acid in pregnancy and has moved toward multiple micronutrient supplements in settings with widespread deficiency. Upper limits still apply — particularly the 3,000 µg RAE ceiling for preformed vitamin A.
What the research used
The amounts, forms and durations published trials of Prenatal multivitamin actually administered.
These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.
Studied for Folic acid before and during early pregnancy
400–800 µg
Strong
Daily, from before conception
The component with the strongest evidence in the whole product. Higher prescribed doses apply after a previously affected pregnancy or with certain conditions and medications.
Studied for Iodine in pregnancy
150–220 µg
Moderate
Daily as potassium iodide
Professional bodies in the US recommend 150 µg/day of supplemental iodine in pregnancy and breastfeeding, against an RDA of 220 µg. Surveys have found many prenatals contain no iodine at all, or amounts far from the label.
Studied for Iron in pregnancy
27 mg
Strong
Daily elemental iron
The RDA in pregnancy. WHO recommends routine daily iron and folic acid supplementation in pregnancy; some high-income guidelines supplement based on ferritin and haemoglobin instead.
This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.
When it was taken
Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.
1 of 2 timings below were actually compared in a trial. The rest reflect convention or pharmacology.
🍽️With food
Moderate
Usually taken with food because the iron content causes nausea on an empty stomach — a meaningful consideration in the first trimester. Iron absorption is better fasted, so this is a deliberate trade of absorption for tolerability.
Timing was tested. A trial compared this window against another and reported a difference.
🌙Evening
Not enough
Often shifted to bedtime when morning sickness makes daytime dosing impossible. Practical rather than tested.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.
The evidence in depth
Best supported: Moderate
What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.
Iron supplementation in pregnancy reduces maternal anaemia and iron deficiency at term, which is well documented. Whether every pregnant woman needs routine iron, or only those with demonstrated deficiency, differs between national guidelines.
Moderate evidence. Several human studies point the same way, with real caveats.
Multiple micronutrient supplements reduce low birthweight and small-for-gestational-age births compared with iron and folic acid alone in trials conducted largely in low- and middle-income settings. The folic acid and iodine components have their own stronger evidence; the benefit of the additional micronutrients in well-nourished women is much less clear.
Moderate evidence. Several human studies point the same way, with real caveats.
Iodine deficiency in pregnancy impairs fetal brain development, and correcting it in deficient populations improves child cognitive outcomes. In iodine-sufficient populations, supplementation trials have not shown a cognitive benefit and one found no effect on child IQ.
Limited evidence. Early human work, or mostly lab and animal research.
Randomised controlled trial · American journal of perinatology · 2024 · PMID 38228158
Deep research mode adds each paper’s own conclusion and stated limitations.
Things to know
Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.
Avoid
Preformed vitamin A must stay low
Retinol is teratogenic above roughly 10,000 IU/day in early pregnancy. Prenatals should supply vitamin A predominantly as beta-carotene, and a general multivitamin, a cod liver oil capsule or a high-dose vitamin A product taken alongside can push total retinol into the range associated with birth defects.
Worth knowing
Iron overdose is a leading cause of poisoning deaths in young children
Prenatal tablets contain enough iron to be lethal to a toddler, and they are often in homes with small children by definition. Child-resistant packaging, storage out of sight, and immediate poison-centre contact after any suspected ingestion are the standard precautions.
Worth knowing
Content frequently does not match the label
Independent analyses of prenatal products have found iodine content varying widely from label, folate forms differing from what is stated, and detectable heavy metals in some products. Third-party testing matters more here than in almost any other category.
Worth knowing
Gummy prenatals usually omit iron
Iron tastes metallic and is generally left out of gummy formats, so a gummy prenatal often supplies no iron at all — the nutrient most likely to be needed. Many also omit iodine.
Worth knowing
Constipation and nausea are the usual reasons people stop
The iron content commonly causes constipation and nausea. Alternate-day dosing, lower-dose iron or a different iron salt are options worth raising with a midwife or doctor rather than simply stopping.
In the food catalogue
The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.