Supplements When Trying to Conceive: Folic Acid, Vitamin D and What to Avoid
Supplement aisles are crowded, and many products marketed for fertility or pregnancy promise a lot. The official advice is much shorter than the shelves suggest. This guide sets out what the NHS recommends, so you can check anything you are considering against it. Guidance can be updated, so always confirm with your midwife, GP or pharmacist.
Folic acid
- Dose: 400 micrograms of folic acid every day.
- When to start: when you are trying to get pregnant (ideally three months before), or as soon as you find out you are pregnant.
- How long: for the first 12 weeks of pregnancy. The NHS adds that taking it for longer will not harm your baby.
Who is advised a higher dose?
The NHS advises a higher dose of 5 mg if you are planning a pregnancy or are under 12 weeks pregnant and have certain risk factors. Examples listed include a neural tube defect in you or the baby's father, diabetes, a blood condition such as sickle cell anaemia or thalassaemia, or taking epilepsy or HIV medicine. This higher dose can be prescribed by a GP, so ask rather than buying over the counter.
Vitamin D
- Dose: 10 micrograms of vitamin D every day during pregnancy.
- Months: the NHS says to take it from early October to late March, when sunlight alone cannot provide enough vitamin D.
- All year: the NHS advises taking it all year if you usually cover most of your skin outdoors or spend a lot of time indoors, and says you might consider all-year use if you have black or brown skin.
- Upper limit: do not take more than 100 micrograms of vitamin D a day, as it could be harmful.
What to avoid: vitamin A (retinol) and cod liver oil
The NHS is direct on this: do not take cod liver oil or supplements containing vitamin A (sometimes called retinol) when you are pregnant, because too much vitamin A can harm your baby's development. It also advises avoiding foods high in vitamin A, with liver given as an example.
This matters because vitamin A turns up in places you might not expect: multivitamins, hair, skin and nail gummies, and some “beauty from within” blends. Read the label for “vitamin A”, “retinol” or “retinyl” and check with your pharmacist if you are unsure. Our label-checking guide goes into more detail.
Iron and other supplements
On iron, the NHS says levels are checked at your booking appointment and again around 28 weeks, and that your GP or midwife may recommend iron supplements. The page does not give an iron dose, so do not self-prescribe.
Practical tip: if you want your folic acid from a multivitamin rather than a standalone tablet, check that it contains 400 micrograms and no vitamin A before you buy. Ask your pharmacist if the label is unclear.
The bottom line
Official advice when you are trying to conceive comes down to folic acid, vitamin D at the right times, and no vitamin A supplements or cod liver oil. Anything beyond that is worth a conversation with your GP or pharmacist first.
Frequently Asked Questions
How much folic acid should I take when trying to conceive?
The NHS recommends 400 micrograms every day, starting when you are trying to get pregnant (ideally three months before) or as soon as you find out you are pregnant, and continuing for the first 12 weeks.
Who needs the higher 5 mg dose of folic acid?
The NHS lists risk factors including a neural tube defect in you or the baby's father, diabetes, a blood condition such as sickle cell anaemia or thalassaemia, or taking epilepsy or HIV medicine. A GP can prescribe the higher dose.
Do I need vitamin D when trying to conceive?
The NHS recommends 10 micrograms daily during pregnancy, from early October to late March, and all year for some people, such as those who cover most of their skin outdoors or spend a lot of time indoors.
Why avoid vitamin A supplements?
The NHS says too much vitamin A can harm a baby's development, so supplements containing vitamin A (retinol) and cod liver oil should be avoided in pregnancy.
Are fertility supplements necessary?
This guide covers only what the NHS recommends. Anything beyond folic acid and vitamin D should be discussed with your GP or pharmacist first.
Sources
- NHS. Pregnancy vitamins and supplements. Page last reviewed 3 June 2026. nhs.uk
- NHS. Trying to get pregnant. Page last reviewed 2 June 2026. nhs.uk
This article is general information, not medical advice. If you have a skin or scalp condition, or you are pregnant, breastfeeding or taking medication, speak to a doctor, pharmacist or dermatologist before changing your routine.
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