Pregnancy and preconception

Written by Katherine Nicholls
Katherine Nicholls
Nutritionist Resource Content Team

Last updated 5th September 2022 | Next update due 4th September 2025

Whether you’re in the early stages of planning for a family or are already pregnant, chances are, you’re giving your health and well-being some extra attention. A part of this should involve your diet.

Here we’ll look at preconception tips, the vitamins and minerals you need during pregnancy, what foods to avoid and how a nutritionist can support you.

Trying to get pregnant

Giving your body the fuel it needs during preconception and pregnancy is vital for a healthy parent and baby. Contrary to popular belief, you do not need to ‘eat for two’, however, it is important to ensure you’re getting the right nutrients and are avoiding foods that can be harmful to the baby.

All of us should be working on eating a varied and balanced diet, full of fruits and vegetables. If you’re trying to get pregnant, this is especially important. Advice on balanced diets currently suggests eating starchy foods, moderate amounts of meat, fish and dairy and at least five portions of fruit and vegetables a day. Avoiding excessively sugary foods or foods high in saturated fats is also recommended. 

Those actively trying for a baby are advised to take a folic acid supplement whilst trying and up until the 12th week of pregnancy. This helps reduce the risk of your baby being born with a neural tube defect.

It’s also recommended that you stop drinking alcohol and stop smoking. And finally, it’s believed that body weight can impact your fertility. If this is the case for you, you may want to make changes to your diet to either gain or lose weight.

Oily fish (that’s salmon, trout, herring, mackerel, sardines, fresh tuna) contain omega 3 fats, which the body needs but can’t make itself. These fats are the building blocks of all hormones and, if your body doesn’t have enough of them, your fertility could be compromised.

- Ailsa Hichens BA (Hons) Dip ION BANT CNHC.

Pregnancy and nutrition

Vitamins and minerals to be aware of

When you are pregnant, there are a number of vitamins and minerals that can help improve your chances of a safe and healthy pregnancy. 


During pregnancy, you should try to ensure you are eating plenty of foods that are rich in calcium such as green vegetables, milk (pasteurised or ultra-heat treated - UHT) yoghurt and other dairies. A diet rich in calcium (especially during the last 10 weeks of pregnancy), will ensure your baby develops strong teeth and bones.


When you’re pregnant, your body will begin producing more female hormones than usual which will help the pregnancy run smoothly. The problem with the extra hormones is that they tend to slow bowel movements which can lead to constipation.

Eating lots of fibre will help to both prevent and remedy constipation whilst promoting normal bowel activity. Fibre can be found in fruit, vegetables, wholemeal bread, prunes/prune juice and cereals.

Folic acid

Folic acid is a B vitamin which plays a key role in the production and division of cells. It can be found in green, leafy vegetables such as spinach and kale, fortified cereals and grains, orange juice and in supplements.

Research has shown that women and people who are pregnant who get 400 micrograms of folic acid per day both prior to conception and throughout early pregnancy will significantly reduce the risk of their baby being born with a neural tube defect (by up to 70%).

A neural tube defect is a birth defect which involves the incomplete development of the brain or spinal cord, of which spina bifida and anencephaly are among the most common.

If you are pregnant or trying to conceive then, as well as taking a supplement, you should also be topping up levels of natural folate which can be found in baked beans, lentils, leafy green vegetables and sprouts.

If you are epileptic, diabetic or have coeliac disease then you may require a higher dose of folic acid or may be on medication that will work against it. If this is the case then visit your GP before taking folic acid so they can advise you on the safest course of action.


Iron is an important mineral which is essential for the production of haemoglobin (the protein in red blood cells which carry oxygen around the body).

When you become pregnant, the amount of blood in your body will increase by approximately 50% to accommodate the baby, meaning that the body will need to produce more haemoglobin so that it can carry the additional blood.

Those who are pregnant should ensure their iron levels are topped up by eating plenty of lean meat, leafy green vegetables and nuts. If iron levels drop too low then this could result in iron-deficiency anaemia, a condition caused by a lack of red blood cells in the body which can cause fatigue.

Iron-deficiency anaemia is not uncommon in pregnant people due to the extra demand the body places on iron, vitamin and mineral stores during this time.

Iron deficiency anaemia is extremely common in pregnancy, due to the increase of blood volume. You can boost iron sources naturally by eating dried fruit, nuts, seeds and lean red meat. Top tip: combine iron-rich foods with natural sources of vitamin C to increase absorption (such as citrus fruits and tomatoes!).

- Hayley Down, Hayley Down Nutrition, Bsc (Hons), DipNT, mANP, rGNC..

Vitamin A

Some research has suggested that high doses of vitamin A can build up in the liver and cause harm to an unborn baby. In light of this, the Department of Health advises pregnant people to steer clear of foods containing a high vitamin A concentration and highlight that some supplements you may already be taking are high in vitamin A.

Vitamin D

Getting enough vitamin D while pregnant will help to ensure your baby develops strong and healthy bones. It is recommended that you get 10 micrograms a day and should consider taking a supplement of this amount. A small amount of vitamin D can be obtained from natural sources such as certain foods and the sun, though it can be difficult to fulfil the daily recommended amount through food and sun exposure alone.


Iodine is important for the correct development of the baby's brain. Adults are advised to have 150 micrograms of iodine per day, and pregnant/breastfeeding women should get 200 micrograms per day. Having too much or too little can affect the production of thyroid hormones so it's important that you speak to a doctor about your requirements. 

If you are struggling to meet your iodine requirements through diet alone, a supplement may be advised. Many (but not all) pregnancy multivitamins on the market contain iodine, so check this before getting additional supplements. A supplement should contain around 140-150 micrograms of your daily intake with your diet providing the rest.

Foods to avoid during pregnancy

When pregnant there are certain foods that you should avoid or eat with caution in order to reduce the risk of food poisoning. These include:

Alcohol – Consumption of alcohol during pregnancy can cause harm to an unborn child, with some evidence suggesting that it is linked to an increased risk of birth defects and low birth weight. It may also prevent you from effectively absorbing all of the nutrients needed from certain foods.

Caffeine – Similarly to alcohol, caffeine can interfere with the body's ability to absorb important nutrients so mothers-to-be should try to limit their intake to no more than 200mg per day, (equivalent to approximately four cups of coffee or six cups of tea).

Cheese – Cheeses which are either veined such as blue cheese or stilton, or those which have a rind such as camembert or Brie should be avoided. These cheeses contain a bacteria known as listeria which can be harmful to an unborn baby. Cheddar cheese, cheese spread, cottage cheese and processed cheese are all fine and do not carry any risks.

Eggs – Either raw or partially cooked eggs could put mothers or parents-to-be at risk of salmonella so be sure to cook your eggs fully (solid egg and yolk). Homemade salad dressings and mayonnaise are things to look out for whilst eating out but the supermarket varieties usually only contain pasteurised egg and will, therefore, be safe to consume.

Fish – Pregnant women are encouraged to include fish in their diets as it provides lots of healthy vitamins and nutrients. However, there are certain fish which should be avoided as their high mercury content could affect the development of a baby's nervous system.

Though the amount consumed would have to be extremely high to pose a risk, it's best to limit tuna consumption and to avoid marlin, swordfish and shark. All other fish is fine to eat regularly but make sure it is cooked thoroughly.

Pate – Pate commonly contains listeria so is best avoided.

Raw or undercooked foods – Raw foods are a breeding ground for bacteria so during pregnancy it is best to thoroughly cook any meat, fish, shellfish etc as this will reduce the likelihood of food poisoning.

Common pregnancy and nutrition problems

Coeliac disease and diabetes

If you are pregnant and have coeliac disease or diabetes then you may benefit from consulting a nutritionist who will make sure you are eating a well-balanced and healthy diet which is going to provide your baby with all of the nutrients it needs. If this service is not available on the NHS in your local area then there are plenty of independent nutritionists who can provide this service.


As mentioned previously, constipation can become an issue for pregnant people due to the high volume of female hormones slowing movements in the bowel and intestines. To prevent discomfort eat lots of fibre and drink lots of fluids as this will ensure the bowel and intestines continue to function as normal.

Food cravings and aversions

A desire for specific foods may increase during pregnancy and some mothers-to-be may find themselves craving anything and everything - from pickles to a cube of chocolate wrapped in parma ham. Generally, cravings are unlikely to cause any negative effects if the rest of the diet is healthy and balanced, though craving non-food items such as washing powder, soap or charcoal (known as pica), is dangerous for both parent and child and advice should be sought from a professional.

Aversions are the opposite of food cravings, foods which you used to like but now find unappealing. Unfortunately, some find that it is specific nutritious foods which they can no longer tolerate so if this is the case then it is best to try substitutes such as a different fruit or veg, or you could try cooking them in a different form such as eating raw with dips or mixed into a dish.

Morning sickness

Morning sickness is characterised by frequent sickness, nausea and vomiting which occurs predominantly during the first three months of pregnancy (though it does happen past this point for some).

The exact cause of morning sickness is unknown, though experts believe it is a combination of hormonal changes and blood sugar imbalance.

If you are struggling to eat or keep food down then try eating small meals rich in carbohydrates every few hours, avoid eating fatty foods, steer clear of tea and stick to foods which don't involve a lot of preparation (if you are having a good day you could prepare meals in advance and freeze them).

There is some thought that drops in blood sugar may cause some cases of morning sickness. In this case, try to have a small breakfast, and then a small snack about every 2-3 hours outside of main meals. Make sure the foods you eat are low GI, that is those that minimally disrupt your blood sugar.

- Robin Dowswell BSc MFNTP.

Vegetarian and vegan parents to be

It is perfectly healthy to remain vegetarian or vegan throughout pregnancy so long as the diet is well-planned and all food groups and vitamin and mineral requirements are met. If you are struggling to plan your diet, or are feeling weak during pregnancy then it is advisable to get in touch with your GP or a qualified nutritionist for professional advice.

Healthy Start 

Some mothers and parents may qualify for 'Healthy Start' vouchers. These vouchers are distributed by the NHS and can be used to buy milk, infant formula and plain fresh and frozen fruit and vegetables from local shops and supermarkets. You can also get coupons which can be exchanged locally for free vitamins. Visit HealthyStart to find out if you qualify.

How can a nutritionist help me?

Having a varied and balanced diet has been linked to an increased chance of healthy birth weight, increased brain development and a reduction of some birth defects. The positive aspects of a healthy diet also cross over to the mother, having been linked to a reduction in morning sickness, fatigue, pre-eclampsia, mood swings, constipation and post-natal recovery.

Conflicting and mixed messages can make it difficult to know exactly what it means to have a ‘balanced diet’ however. If you are unsure or concerned about your diet then consulting a nutrition professional may help you to feel more at ease. A nutritionist will be able to assess your personal circumstances and current diet and use this information to formulate a diet plan that can help give your baby the best possible start in life.

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