Pregnancy vitamins guide: what to eat and what not to eat

Pregnancy is an exciting time when your body can change quickly. A few key vitamins and supplements can help to support your changing nutritional needs at this time.

What are the four vitamins and supplements to take during pregnancy?

Folic acid

You need twice as much folic acid during pregnancy than at any other time. Folic acid is the synthetic form of the naturally occurring B vitamin folate, which is found mainly in green leafy vegetables and wholegrains. Folic acid is more readily absorbed than folate, and is also used more efficiently in the body.

Folic acid is needed by rapidly dividing cells and good intakes are vital, especially during the first trimester, to help protect against a type of developmental abnormality known as a neural tube defect (such as spina bifida), which arises between the 24th and 28th day after conception.

The Department of Health recommends that you take 400mcg folic acid every day from before trying to conceive until you are 12 weeks pregnant (I suggest continuing until the end of pregnancy, too). You should also eat foods that provide folate such as green leafy vegetables, brown rice and fortified foods (such as cereals) as part of a healthy diet.

Vitamin D3

Vitamin D is needed for the absorption of calcium from food, and is also important for general immunity. The Department of Health now recommends that you take 10mcg of vitamin D per day during pregnancy and when breastfeeding (to boost calcium absorption, and to protect against infant rickets).

Vitamin D can also help with a natural delivery, which doesn't require medical intervention.

A study published in 2022, involving 965 pregnant women from Southampton, Oxford and Sheffield, found that those who took an extra 1,000IU (25mcg) of vitamin D each day were more likely to have a natural delivery without medical assistance: two-thirds of those given the supplement had a natural delivery, compared to just over half of those who were not.

Look for the form known as vitamin D3, as this is more readily absorbed and used by the body than vitamin D2.

Multivitamin and mineral

A multivitamin and mineral supplement designed for pregnancy and breastfeeding is a good way to get the folic acid, vitamin D and other key nutrients you need at this time to safeguard against deficiencies that can, for example, increase feelings of tiredness.

Supplements designed for pregnancy will not contain vitamin A, and usually have boosted levels of B vitamins, including folic acid, and vitamin D.

Omega-3s

The long-chain omega-3 essential fatty acids found in oily fish are especially important for a baby's developing brain, eyes and nervous system. It is important to only take a DHA-rich omega-3 supplement designed for use in pregnancy, to ensure you get the right blend of essential fatty acids.

It should be noted that women who are pregnant should avoid taking cod liver oil supplements, as these contain high amounts of vitamin A, which is best avoided during pregnancy.

Nutritionist Rob Hobson's top pregnancy diet tips

At any stage of life, it is important to eat a healthy balanced diet, but this is even more important if you are pregnant or trying to conceive. Eating nourishing foods will give you the most nutrients, which will help assist your baby's growth and development.

There is no special diet for pregnancy, but this is a time when you should get the basics right. This includes:

• Eating plenty of fruits and vegetables, to provide essential vitamins and minerals. These foods are also a good source of fibre, which can help to ease the constipation that may be common during pregnancy.
• Eating a source of starchy foods with meals, to provide an important source of energy. Always choose wholegrain foods such as brown bread, pasta and rice over more refined varieties. Oats, potatoes and corn also fall into this category.
• Eat protein with every meal, which may include dairy foods, lean meats, poultry, fish, beans and pulses or tofu. Beans and pulses are a healthy addition to the diet as they are rich in essential minerals and fibre to help support good digestion.
• Eating calcium-rich foods for bones and teeth. These foods are also often supplemented with vitamin D, which can have a further beneficial effect. This is especially important during pregnancy as the demands for calcium may increase during the third trimester. If you're on a plant-based diet then always choose dairy alternatives that are fortified with calcium and vitamin D.
• Eat plenty of iron-rich foods, as many women often have low levels of this mineral. During the third trimester of pregnancy, the demand for iron also increases. Good sources are red meat, dark green vegetables, dried fruit, dried spices, beans, pulses and fortified cereals. Try eating plant-based sources of iron with a food or drink rich in vitamin C such as fruit juice, peppers and citrus fruits to increase absorption in the body.

Also, remember that you are not eating for two: the additional energy required during pregnancy is only between 300 and 400 calories per day. You certainly do not need to focus on calories during pregnancy, but try not to overeat, as this may lead to unnecessary weight gain.

What not to eat when pregnant

There are certain foods to avoid when pregnant to help protect your health. These include:

• Fish rich in heavy metals such as mercury, as this may impact the development of your baby. High-mercury fish include swordfish, fresh tuna, and shark, and should probably be avoided during pregnancy. The basic healthy eating guidance of two servings of oily fish per week, such as trout and salmon, applies during pregnancy, but try to avoid eating any more than this, or consider a supplement containing omega-3.
• Raw meat and fish, as this puts you at greater risk of food poisoning from bacteria and parasites such as Listeria and Salmonella. Although the likelihood of this may be slim, there is still a risk.
• Eggs not produced under the British Lion Code of Practice, which may not be safe to eat raw or partially cooked. The Code guarantees that flocks that produce the eggs have been vaccinated against salmonella.
• Unpasteurised cheeses, which may run an increased risk of Listeria poisoning.
• Liver and liver-containing foods such as pâté, sausages and haggis. Liver contains very high amounts of vitamin A, which may be harmful to your baby.

The previous advice regarding peanuts in pregnancy was to avoid them if there was a history of allergy in the immediate family, such as asthma, eczema, or a food allergy. This advice has now changed, because there is no clear evidence to prove that eating peanuts during pregnancy may increase the risk of your baby developing a peanut allergy.

Pregnancy supplements

Regarding supplements, I would advise choosing a preparation designed for pregnancy, to ensure that you are not unwittingly getting a heavy dose of vitamin A in your diet. Always seek trustworthy advice when taking supplements during pregnancy.