What Should a Prenatal Vitamin Contain? The Nutrients and Daily Amounts

What should a prenatal vitamin contain?

A prenatal vitamin should give you at least 400 micrograms (mcg) of folic acid a day, along with iron, iodine and vitamin D. ACOG says that eating healthy foods and taking a prenatal vitamin every day should supply all the vitamins and minerals you need during pregnancy.

ACOG's daily amounts are totals, and the pill does not have to supply all of it: ACOG says the best way to get these nutrients is through food. Choline, for example, is not found in most prenatal vitamins, according to ACOG, so it has to come from your diet.

How much folic acid should a prenatal vitamin have?

At least 400 mcg. ACOG, the CDC and the NHS all give that figure, and the US Preventive Services Task Force recommends a daily supplement with 400 to 800 mcg (0.4 to 0.8 mg) for anyone planning to or who could become pregnant.

Folic acid lowers the chance of neural tube defects, which are problems with the baby's brain or spine such as spina bifida. The NHS adds that it can also help prevent cleft lip and palate and some heart conditions. ACOG says folic acid is the only form of folate proven to help prevent neural tube defects, and asks you to check that it is on your vitamin's ingredients list.

Some people need a much higher dose. ACOG gives 4 mg (4,000 mcg) a day if you have already had a child with a neural tube defect, and the CDC gives 4,000 mcg a day after a pregnancy affected by one. ACOG says to take it as a separate supplement from at least 3 months before pregnancy through the first 3 months. The NHS recommends 5 mg a day, which a GP can prescribe, if you or the baby's father has a neural tube defect or a relative with one, if you have had an affected pregnancy, if you have diabetes, sickle cell anaemia or thalassaemia, or if you take medicine for epilepsy or HIV.

When should you start taking prenatal vitamins?

Before you get pregnant if you can, and otherwise as soon as you find out. The CDC says to start folic acid at least 1 month before conception, ACOG says at least 1 month before pregnancy, and the NHS says ideally 3 months before.

The CDC explains why: neural tube defects happen in the first few weeks of pregnancy, often before you know you are pregnant. The USPSTF says the critical period starts at least 1 month before conception and runs through the first 2 to 3 months of pregnancy.

ACOG and the NHS both name the first 12 weeks for folic acid, and the NHS says taking it for longer will not harm your baby. ACOG advises taking a prenatal vitamin before pregnancy and continuing after you get pregnant. It also says prenatal vitamins may help reduce nausea and vomiting if you start taking them before you get pregnant. Other ways to ease it are in how to ease morning sickness.

How much iron, iodine and vitamin D do you need?

ACOG gives 27 mg of iron, 220 mcg of iodine and 600 IU (15 mcg) of vitamin D a day in pregnancy.

ACOG says your iron need rises from 18 mg a day to 27 mg in pregnancy, and that most prenatal vitamins have that amount. Gummy vitamins cannot hold as much iron as regular prenatal vitamins, ACOG adds, so you may need an extra iron supplement; ask your ob-gyn how much. ACOG also recommends a blood test for anemia during pregnancy, and in the UK the NHS checks iron at the booking appointment and again at around 28 weeks. The booking visit is covered in the first prenatal appointment.

In the US, the American Thyroid Association recommends a supplement with 150 mcg of iodine a day for anyone pregnant, breastfeeding or planning a pregnancy. Not every prenatal vitamin has it: a 2019 study in the journal Thyroid found iodine in 34 of the 59 top-selling US prenatal vitamins it analyzed, from sales in 2016 and 2017.

For vitamin D, ACOG says you need 600 IU a day whether you are pregnant or not, and a blood test can check your level if your ob-gyn thinks it may be low. The NHS recommends a 10 mcg (400 IU) supplement every day from early October to late March, and all year if you cover most of your skin outdoors or spend a lot of time indoors. It says to consider taking it all year if you have black or brown skin.

Does a prenatal vitamin need DHA?

ACOG gives no daily amount for DHA, an omega-3 fat found in fish; its advice for omega-3s is 2 or 3 servings of fish or shellfish a week, at 4 ounces (113 g) a serving. ACOG says omega-3s may be important for your baby's brain development before and after birth.

Advice on DHA supplements is less settled. The FDA says omega-3 supplements lack the protein, vitamins and minerals in fish, and that research on their benefits is still underway. A 2018 Cochrane review of 70 trials with 19,927 women found less preterm birth, both before 37 weeks and before 34 weeks, in women who took omega-3 supplements or ate more omega-3 foods. It also found that pregnancies going past 42 weeks were probably more common with omega-3. For eating fish safely, see which fish are low in mercury.

Can you take too much of a prenatal vitamin?

Yes. ACOG says not to take more than the recommended amount a day, because some ingredients, such as vitamin A, can cause birth defects if you double or triple the dose. Read the bottle to see how many pills make one daily serving.

The NHS says not to take cod liver oil or any supplement containing vitamin A (sometimes called retinol) in pregnancy, and to avoid foods high in vitamin A, such as liver. Other foods to skip are in foods to avoid during pregnancy. The NHS also says not to take more than 100 mcg of vitamin D a day.

On choosing one, ACOG suggests a vitamin from a company with a long, reputable history over a new brand found on social media, and says an ob-gyn or registered dietitian can recommend one.

When should you ask your doctor or midwife about vitamins?

• Before you try to get pregnant, if you have had a pregnancy affected by a neural tube defect or fall into one of the NHS higher-dose groups above. The CDC says to talk with your doctor before a pregnancy if a previous one was affected.
• If you take gummy vitamins, about extra iron.
• If you feel more tired than usual. The NHS says low iron can cause this and anaemia, and if your iron is low your GP or midwife will recommend supplements.
• If you eat a vegetarian diet, about vitamin B12.
• Before taking any other supplement or herbal remedy. ACOG says some vitamins and herbal remedies can be harmful to a fetus.