Vitamins for Pregnancy: What the NHS Recommends and What the Evidence Says

Are you getting the right nutrients for pregnancy?

Pregnancy increases the body's demand for several key nutrients. Some — like folate — are critical in the earliest weeks, often before a woman knows she is pregnant. Others, like iron and calcium, become increasingly important as the pregnancy progresses.

The challenge is that general advice on pregnancy supplements can be vague, contradictory, or driven by marketing rather than evidence. This guide focuses on what the NHS, NICE, and peer-reviewed research actually recommend — and where the gaps in the average UK diet tend to fall.

Before we go any further: if you are pregnant, planning a pregnancy, or breastfeeding, always discuss supplementation with your GP or midwife. No article replaces individualised medical advice, and your healthcare provider can assess your specific needs based on blood tests, medical history, and dietary intake.

What do the NHS and NICE recommend for pregnancy?

The NHS advises two specific supplements for all pregnant women:

Folic acid — 400 micrograms (µg) daily, from before conception until at least 12 weeks of pregnancy
Vitamin D — 10 micrograms (µg) daily throughout pregnancy and breastfeeding

NICE guideline NG201 (Antenatal Care, 2021) reinforces these recommendations and adds that women with certain risk factors — including diabetes, BMI above 30, or a previous pregnancy affected by a neural tube defect — should discuss higher-dose folic acid (5mg daily) with their doctor.

Beyond folic acid and vitamin D, the NHS does not recommend routine supplementation with other nutrients for all pregnant women. However, several nutrients deserve attention depending on individual circumstances.

Why is folate so important before and during pregnancy?

Folate is essential for DNA synthesis and cell division — processes that occur at an extraordinary rate during early embryonic development. The neural tube, which forms the brain and spinal cord, closes within the first 28 days after conception. Inadequate folate status during this window is a well-established risk factor for neural tube defects (NTDs) such as spina bifida.

This is why the NHS recommends starting folic acid supplementation before conception, not just after a positive pregnancy test. Many pregnancies are unplanned, which is why public health guidance extends to all women of childbearing age who could become pregnant.

The authorised health claims for folate under EU Regulation 432/2012 (retained in UK law) include:

Folate contributes to maternal tissue growth during pregnancy
Supplemental folic acid intake increases maternal folate status, and low maternal folate status is a risk factor in the development of neural tube defects in the developing foetus

Data from the NDNS Years 9–11 report found that 89% of UK women of childbearing age (16–49 years) had red blood cell folate concentrations below the threshold associated with increased NTD risk (748 nmol/L). That is a striking number, and it underscores why supplementation rather than diet alone is the recommended approach.

Does the form of folate matter? Folic acid vs 5-MTHF

Most pregnancy supplements use synthetic folic acid (pteroylmonoglutamic acid). The body must convert folic acid through several enzymatic steps — involving the MTHFR enzyme — into its active form, 5-methyltetrahydrofolate (5-MTHF), before it can be used.

A significant proportion of the population carries genetic variants that reduce MTHFR enzyme activity. As Scaglione and Panzavolta (2014) described in their review, 5-MTHF has practical advantages over synthetic folic acid: it does not require enzymatic conversion, it avoids the potential masking of vitamin B12 deficiency, and its bioavailability is not affected by MTHFR genotype variations.

Bailey and Ayling (2018) further demonstrated that 5-MTHF raises serum folate levels more rapidly and uniformly than folic acid, without generating unmetabolised folic acid in the blood.

PARTICULAR uses 5-MTHF (Quatrefolic) — the body-ready form — rather than synthetic folic acid. Both forms are available in the ingredient catalogue.

What role does vitamin D play during pregnancy?

Vitamin D is the one nutrient where supplementation is recommended for the entire UK population, not just pregnant women. The Scientific Advisory Committee on Nutrition (SACN) recommended in 2016 that all UK adults take 10µg (400 IU) of vitamin D daily, particularly during autumn and winter.

For pregnant women, adequate vitamin D status is important for both maternal and foetal health. The authorised health claims under EU Regulation 432/2012 include:

Vitamin D contributes to the normal absorption and utilisation of calcium and phosphorus
Vitamin D contributes to the maintenance of normal bones
Vitamin D contributes to the normal function of the immune system
Vitamin D contributes to the maintenance of normal muscle function

A standardised analysis of over 55,000 Europeans found that approximately 13% had serum 25(OH)D concentrations below the deficiency threshold of 30 nmol/L, rising to 17.7% during extended winter (Cashman et al., 2016). Women with darker skin, those who cover their skin for cultural reasons, and those who spend limited time outdoors are at particularly high risk.

The Cochrane review by Palacios et al. (2019) examined vitamin D supplementation during pregnancy and found that supplementation probably reduces the risk of pre-eclampsia when combined with calcium, though the evidence base for some outcomes remains limited.

D3 vs D2: which form is better?

A meta-analysis by Tripkovic et al. (2012) found that vitamin D3 (cholecalciferol) is significantly more effective than vitamin D2 (ergocalciferol) at raising and maintaining serum 25(OH)D concentrations. PARTICULAR uses vitamin D3.

Why do iron requirements increase during pregnancy?

Iron requirements rise substantially during pregnancy. The body needs additional iron to expand maternal red blood cell mass, support placental development, and supply the growing foetus. Achebe and Gafter-Gvili (2017) estimated that iron needs increase exponentially during pregnancy to meet these demands, with total iron requirements across the full pregnancy estimated at approximately 1,000mg.

Even before pregnancy, iron status in UK women is a concern. The NDNS Years 9–11 report found that 25% of women aged 19–64 have iron intakes below the Lower Reference Nutrient Intake (LRNI) — the level below which deficiency is likely.

The authorised health claims for iron include:

Iron contributes to the normal formation of red blood cells and haemoglobin
Iron contributes to normal oxygen transport in the body
Iron contributes to the reduction of tiredness and fatigue
Iron contributes to normal energy-yielding metabolism
Iron contributes to normal cognitive function

The NHS does not recommend routine iron supplementation for all pregnant women but advises that iron status should be assessed through blood tests at the booking appointment and at 28 weeks. Women found to be iron-deficient should be offered supplementation.

Which form of iron matters

The form of iron significantly affects tolerability. Tolkien et al. (2015) found in their systematic review and meta-analysis that ferrous sulfate — the most commonly prescribed form — significantly increases gastrointestinal side effects compared to placebo. This is particularly relevant during pregnancy, when nausea and digestive discomfort are already common.

Is iodine a concern during pregnancy in the UK?

Iodine is essential for thyroid hormone synthesis, and thyroid hormones play a critical role in foetal brain development — particularly during the first trimester, before the foetal thyroid becomes functional.

The WHO recommends a daily iodine intake of 250µg during pregnancy and lactation, compared to 150µg for non-pregnant adults. The UK has no formal iodine supplementation programme, and the UK diet relies heavily on milk and dairy as iodine sources.

A cross-sectional survey by Vanderpump et al. (2011) found that 51% of UK schoolgirls had mild iodine deficiency based on urinary iodine concentration. Bath et al. (2013), using data from the Avon Longitudinal Study of Parents and Children (ALSPAC), found an association between mild-to-moderate iodine deficiency in early pregnancy and lower verbal IQ and reading scores in offspring at age 8–9.

The authorised EU health claim for iodine:

Iodine contributes to the normal production of thyroid hormones and normal thyroid function
Iodine contributes to normal cognitive function

Women following plant-based diets, those who avoid dairy, or those with low fish intake may be at particular risk of insufficient iodine status. If you are concerned about your iodine intake during pregnancy, discuss this with your midwife or GP — they can assess whether supplementation is appropriate for you.

How does calcium support pregnancy?

The foetus depends entirely on maternal calcium supply for skeletal development. Calcium demands are highest during the third trimester, when foetal skeletal mineralisation accelerates — the foetus accrues approximately 50mg of calcium per day at 20 weeks, rising to around 330mg per day by 35 weeks.

The UK Reference Nutrient Intake (RNI) for calcium in adult women is 700mg per day, and this does not change during pregnancy — the body adapts by increasing calcium absorption from the gut. However, the NDNS found that 11% of women aged 19–64 and 19% of girls aged 11–18 have calcium intakes below the LRNI.

The authorised health claims for calcium include:

Calcium contributes to the maintenance of normal bones and normal teeth
Calcium is needed for the maintenance of normal bones (and is needed for the normal growth and development of bone in children)

Women who are dairy-free, vegan, or have low calcium intakes should consider whether their diet meets the RNI — and discuss supplementation with their healthcare provider if not.

Which supplements should you avoid during pregnancy?

Not all supplements are appropriate during pregnancy. Some carry specific risks:

Vitamin A (retinol)

Preformed vitamin A (retinol) in high doses is teratogenic — meaning it can cause birth defects. Rothman et al. (1995) found in a study of over 22,000 pregnant women that intakes above 10,000 IU per day of preformed vitamin A were associated with an increased risk of birth defects, particularly when consumed before the seventh week of gestation.

The NHS advises pregnant women to avoid:

Supplements containing vitamin A (retinol), unless specifically advised by a doctor
Liver and liver products (very high in retinol)
High-dose multivitamins not specifically designed for pregnancy

Beta-carotene (the plant form of vitamin A) is not associated with the same risk, as the body regulates its conversion to retinol.

Herbal supplements

The NHS advises caution with herbal remedies during pregnancy, as many have not been tested for safety in pregnant women. This includes supplements such as St John's wort, ginseng, and high-dose green tea extracts.

High-dose single-nutrient supplements

Taking very high doses of individual nutrients (particularly fat-soluble vitamins A, D, E, and K) without medical guidance can carry risks. Always check doses against the recommended amounts and discuss with your healthcare provider.

How do pregnancy nutrients compare? A summary table

Nutrient	NHS/NICE recommendation	Amount	EU-authorised claim	Notes
Folate	Recommended for all	400µg daily (pre-conception to 12 weeks)	Contributes to maternal tissue growth during pregnancy	5mg if higher risk; 5-MTHF bypasses MTHFR variants
Vitamin D	Recommended for all	10µg (400 IU) daily throughout pregnancy	Contributes to maintenance of normal bones	D3 form more effective than D2
Iron	Test and treat if deficient	Varies by individual need	Contributes to normal formation of red blood cells and haemoglobin	25% of UK women aged 19–64 below LRNI
Iodine	No routine recommendation	WHO advises 250µg daily in pregnancy	Contributes to normal production of thyroid hormones	51% of UK schoolgirls mildly deficient
Calcium	No routine recommendation	700mg RNI (unchanged in pregnancy)	Contributes to maintenance of normal bones	11% of women aged 19–64 below LRNI
Vitamin B12	No routine recommendation	1.5µg RNI	Contributes to normal red blood cell formation	Particular concern for vegans
Vitamin A	Avoid retinol supplements	Do not exceed 10,000 IU preformed retinol	—	Teratogenic at high doses

What should you look for in a prenatal multivitamin?

If you are considering a prenatal multivitamin, the evidence points to several features worth checking:

Contains at least 400µg folate — ideally as 5-MTHF rather than synthetic folic acid, to bypass MTHFR conversion issues
Contains 10µg (400 IU) vitamin D3 — the form shown to be more effective at raising serum levels
Contains iodine — particularly important if your diet is low in dairy or fish
Appropriate iron form and dose — if included, look for forms with better tolerability than ferrous sulfate
No preformed vitamin A (retinol) — or at least well below the 10,000 IU upper limit
Transparent labelling — specific forms and doses listed, not just "vitamin B9" or "iron"
Avoids proprietary blends — where individual ingredient amounts are hidden

Not every woman needs the same nutrients in the same doses. A multivitamin designed for a 25-year-old omnivore has different requirements from one for a 38-year-old vegan.

A note on PARTICULAR and pregnancy

PARTICULAR is a personalised food supplement — not a medicine, and not specifically marketed as a prenatal product. This article is educational, based on published NHS guidance and peer-reviewed evidence.

PARTICULAR's questionnaire does account for pregnancy status and other individual factors when generating a personalised formula. However, pregnancy is a period where nutritional needs change rapidly and where the stakes of getting things wrong are higher than usual.

If you are pregnant, planning a pregnancy, or breastfeeding, we strongly recommend discussing any supplementation — including PARTICULAR — with your GP or midwife before starting. Your healthcare provider can review your blood results, dietary intake, and medical history to give you tailored advice that no algorithm can fully replicate.

Key takeaways

The NHS recommends two supplements for all pregnant women: 400µg folic acid (from before conception to 12 weeks) and 10µg vitamin D (throughout pregnancy)
Folate is critical for neural tube development in the first 28 days — starting supplementation before conception is essential because many pregnancies are unplanned
5-MTHF may offer advantages over synthetic folic acid for women with MTHFR variants, as it does not require enzymatic conversion
Iron requirements increase substantially during pregnancy, but routine supplementation is not recommended — the NHS advises testing and treating deficiency on an individual basis
Iodine is an underappreciated nutrient in the UK, with evidence linking mild maternal deficiency to lower cognitive scores in offspring
Avoid preformed vitamin A (retinol) supplements during pregnancy, as high doses are teratogenic
Not all prenatal multivitamins are equal — check forms, doses, and whether vitamin A is included as retinol or beta-carotene
Always discuss supplementation with your GP or midwife before and during pregnancy — personalised medical advice is more valuable than any general guide

Sources cited in this article: