Do you really need to take supplements during pregnancy?

Research says ‘multivitamin and mineral preparations promoted for use during pregnancy are unlikely to be needed’

Any woman who has been pregnant will remember how much effort she put into eating a healthy diet. Many expectant mums also turn to prenatal supplements to optimise their chances of producing a healthy baby and, in later years, a more “intelligent” child.

But experts now warn that many of these daily vitamins are of little or no use.

The Australian research (involving almost 550 pregnant women) published in the Journal of the American Medical Association found there was "little evidence of benefit" after half of the women were given daily supplements while the others took a placebo.

Once the pregnancies were over, the babies were tested at regular intervals until they were seven years old. Results showed no difference between the children’s general intelligence, language skills or overall level of IQ, whether or not their mother had taken supplements while pregnant.


No evidence

These latest findings back up other research (published in the Drug and Therapeutics Bulletin last year), which found no evidence that pregnancy supplements improve the health of women or their babies.

Researchers concluded that “for most women who are planning to become pregnant or who are pregnant, complex multivitamin and mineral preparations promoted for use during pregnancy are unlikely to be needed and are an unnecessary expense”.

Fergal Malone, head of RCSI's Department of Obstetrics and Gynaecology and Master of the Rotunda Hospital, echoes this advice.

“We agree with the studies that show no benefit for routine vitamin supplements in otherwise healthy pregnant women, unless they have a specific dietary deficiency,” he says. “Iron supplements are only recommended if a patient shows evidence of iron-deficiency anaemia.”

The Department of Health recommends that women of child-bearing age take 400 micrograms of folic acid tablet every day while trying to get pregnant and until 12 weeks pregnant.

“Folic acid is important for pregnancy, as it can help to prevent birth defects known as neural-tube defects, including spina bifida,” says a spokesperson. “And foods that contain folate [the natural form of folic acid], such as green, leafy vegetables should also be eaten regularly. However, it’s difficult to get the amount of folate recommended for pregnancy from food alone, which is why it is important to take a folic acid supplement.

“Some women, particularly those who have already had a pregnancy affected by a neural-tube defect, have an increased risk and are advised to take a higher dose of 5 milligrams of folic acid each day until they are 12 weeks pregnant.”

Negative effect

Tracy Donegan, a midwife and the founder of Gentlebirth, says there is no evidence that pregnancy supplements have a negative effect on expectant mothers or their unborn babies, but agrees that folic acid and a good diet are both essential.

“In pregnancy, women are likely to engage in health-promoting activities and at the moment there haven’t been any studies to show taking prenatal supplements are harmful to mum and baby,” she says. “But good nutrition is the foundation of a healthy pregnancy, so if mum is eating a healthy diet with a minimum of processed foods she can skip the vitamins.”

However, Donegan says evidence does support the taking of folic acid supplements. In fact, folate, which is naturally found in some foods, is argued to be a healthier option than the manufactured folic acid.

"Natural folate can be found in spinach and other folate-full green veg as well as orange juice and lentils," she says. "Vitamin D supplementation is also important due to the lack of sun exposure in Ireland and we can't absorb enough from our diet. So low vitamin D levels are associated with an increase in complications for mum."

The experienced midwife also says that sometimes a probiotic can be beneficial.

“Probiotics from both natural food sources and supplements are usually considered safe to take during pregnancy,” she says. “Due to stress and lots of processed foods, our gut bacteria isn’t always as healthy as it could be and probiotics support gut health and immune system and reduce inflammation in the body.

“A large Norwegian study suggested that probiotics may reduce the risk of pre-eclampsia – a very serious complication for mum and baby. Other studies also show a positive effect on anxiety and depression. But always check with your midwife or GP before starting any supplements in pregnancy.”

Marian O’Reilly, chief nutrition specialist at, says the best benefits can be attained with a well-balanced healthy diet.

“Eating a healthy, varied diet pre and during pregnancy will help provide most of the vitamins and minerals needed for mother and baby,” she says. “Early pregnancy can be difficult with morning sickness but eating small amounts frequently can help with this as well as sticking to plain foods.”

Likes reassurance

O’Reilly acknowledges that “some women like the reassurance of taking a pregnancy supplement as well as making improvements to their diet: so folic acid is a must pre-pregnancy and for the first three months. But improvements to the diet are far more beneficial in most cases than taking a supplement.

“The exception to this may be if somebody is anaemic,” which is low in iron. “But including some red meat and plenty of fruit and vegetables in their diet can be equally effective.

“Eating healthily during pregnancy will help your baby develop and grow and keep you fit and well.

“You don’t need to go on a special diet, but make sure that you follow the basic healthy eating guidelines in order to get the right balance of nutrients that you and your baby need.”

See Safefood's pregnancy recommendations at See


Folic acid: Folic acid is a B vitamin found in some foods as well as supplement form. If you have enough folic acid around the time you conceive your baby, then there is less risk of your baby being born with neural tube defects such as spina bifida.

All women who could become pregnant are advised to take a supplement of 400 micrograms of folic acid each day. When you do become pregnant, continue to take the supplement each day for the first 12 weeks of pregnancy. If you’ve just found out you are pregnant and had not been taking folic acid supplements, start them right away and continue to take them until the 12th week of pregnancy.

Folic acid supplements are available over the counter in pharmacies and some supermarkets. If you take folic acid as part of a multivitamin supplement, make sure it contains 400 micrograms of folic acid – and does not contain vitamin A, which could harm your baby.

Folic acid is also found in green vegetables, brown rice, orange juice and some breakfast cereals (check the label). You can boost your folic acid by eating these foods, but you still need to take a supplement to get the full amount you need while you’re pregnant.

Iron: You need extra iron when you are pregnant to make new blood cells for your developing baby. Many women are low in iron even before they become pregnant, so be sure to eat iron-rich foods regularly throughout your pregnancy.

Lean red meat is the best source of iron in the diet. Other good sources are chicken, turkey(especially the dark meat) and oily fish. Liver has lots of iron, but avoid eating it while pregnant because it has very high levels of vitamin A.

Other foods that contain iron include peas, beans, lentils, eggs, wholegrain bread, dried fruit, green vegetables, and some breakfast cereals (check the label). Having salad vegetables, citrus fruits or a glass of fruit juice with meals will boost iron absorption.

Some women are advised by their doctor to take iron supplements during pregnancy. So speak to your doctor if you have a history of heavy periods or anaemia.

Calcium: You need extra calcium in your diet during pregnancy. This allows your baby's bones to grow and develop, while looking after your own bones as well. Dairy foods such as milk, cheese and yoghurt are the best sources of calcium. Pregnant women should have five servings of dairy foods each day. One serving is a glass of milk, a carton of yoghurt (125g) or a matchbox-sized piece of cheese.

Avoid unpasteurised dairy products, soft mould-ripened cheeses such as Camembert or Brie, and all blue-veined cheese because of the risk of listeria food poisoning, which is dangerous for pregnant women.

Other foods that have some calcium include green leafy vegetables (such as broccoli or cabbage); tinned fish where the bones can be eaten (sardines, salmon); nuts; soya products; baked beans; and calcium- enriched juice drinks, breads and breakfast cereals (check the labels).

Vitamin D: In the UK, women who are pregnant or breastfeeding are advised to take supplements containing 10 micrograms of vitamin D each day. In Ireland, pregnant women are advised to take a supplement of 5 micrograms vitamin D per day. Vitamin D is only found in a small number of foods – and we get most of our vitamin D from the sun.

Fish and omega fats: Omega-3 and omega-6 fatty acids are important for the developing baby's brain and eyes. You'll find these fatty acids in oily fish (such as herring, mackerel, sardines, salmon, trout), white fish (cod, plaice, whiting), and some vegetables oils (rapeseed, canola, flaxseed, linseed, walnut).

When you are pregnant, aim to eat two portions of fish each week, one of which is oily. Some types of fish can contain levels of mercury that are too high for your unborn baby. So, during pregnancy you should include a maximum of two portions of oily fish per week. Avoid shark, swordfish and marlin, and limit tuna to four tins per week, or two tuna steaks.


Vitamin A: Having too much vitamin A may harm your unborn baby. Avoid taking fish liver oil or supplements that contain vitamin A while you are pregnant. Eating liver is best avoided while pregnant because it is high in Vitamin A.

Alcohol: Avoid alcohol completely during your pregnancy.

Caffeine: High levels of caffeine might result in babies having a low birth weight, which increases their risk of some health conditions as babies and in later life. High levels of caffeine may also increase the risk of miscarriage. You don't need to cut it out completely but try to keep your caffeine intake below 200mg per day. Caffeine is also found in some cold and flu remedies.

Undercooked or raw eggs: These can increase risk of salmonella food poisoning, which is a much nastier experience when you are pregnant.

Raw shellfish: Raw or undercooked shellfish may contain bacteria or viruses that may cause food poisoning. However, shellfish is perfectly safe to eat when cooked thoroughly.

Allergies: Some guidelines recommend that you avoid peanuts during pregnancy, breastfeeding, and the first three years of childhood. While the evidence to support these guidelines is not conclusive, it is important to be vigilant until there is more concrete evidence one way or the other, especially if there is a history of atopic disease (asthma, eczema, etc) in the family.