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Healthy eating in pregnancy

Bridget Benelam with dietary hints and tips you can give to pregnant women 

 

Pregnancy results in many physiological changes that can place additional requirements on the body, both to support the developing baby and the health of the mother. This means that eating well in pregnancy (and ideally also pre-pregnancy) is important, not only in relation to the short term effects on the health of mother and baby, but also for the long-term health of the child. Evidence is increasing that nutrition and health during pregnancy and in infancy (often referred to as the ‘first 1000 days’ of a child’s life) can have important consequences on health in adulthood, for example, risk of obesity, type 2 diabetes and cardiovascular disease.1

The basic principles of a healthy diet stay the same in pregnancy. Besides all the nutrients that can be obtained from a healthy, varied diet, there are some vitamins and minerals that are of particular note in pregnancy.

Folic acid supplementation (400 micrograms per day for most women) is recommended when trying for a baby and for the first 12 weeks of pregnancy to reduce the risk of neural tube defects. The requirement for folate (the natural form of folic acid) is higher throughout pregnancy, so you should inform pregnant women that it is a good idea to regularly consume folate-containing foods such as oranges, berries, green leafy vegetables, beetroot, beans and wholewheat bread.

Vitamin D and calcium are both important for growth and development of the baby’s skeleton as well as maintaining the mother’s bone health. There is no additional requirement for calcium in pregnancy as the body becomes more efficient at absorbing calcium from foods and drinks. However, it is still important to ensure that calcium-rich foods are consumed. Dairy foods are a good source of calcium (Government recommendations are to choose lower fat/lower sugar versions). Other foods such as calcium-fortified dairy alternatives, green leafy vegetables, canned oily fish and some nuts and seeds can also contribute.

National surveys show that many women of childbearing age have low vitamin D status.2 So you should advise pregnant women to take a daily vitamin D supplement of 10 micrograms, especially from October to March, when sunlight is not strong enough to allow synthesis of vitamin D in the skin. This may be particularly important for women with darker skin or women who cover their skin for religious or cultural reasons as they may be at greater risk of low vitamin D status.3

Low iron status is common in pregnancy due to the increased requirements for a sufficient blood, oxygen and nutrient supply for mother and baby. While iron supplements are not routinely offered unless blood tests show that the mother is anaemic, your advice can reduce the likelihood of this becoming a problem by emphasising the importance of consuming iron-rich foods in order to maintain their iron levels. Sources of iron include lean red meat, pulses, nuts, eggs, green leafy veg such as watercress, wholemeal bread, dried fruit and fortified foods such as breakfast cereals. Iron absorption from the plant based foods listed can be increased by including vitamin C (e.g. a small glass of orange juice with these foods).

Fibre: Constipation is common in pregnancy and consuming fibre-providing foods such as wholegrains, potatoes with skins, dried fruit, nuts, seeds, fruit and vegetables, alongside plenty of fluids, is advisable.

Varied and balanced diets can be especially important in some groups such as vegetarians and vegans, and young women under 20. For example, as vegan sources of vitamin B12 are particularly limited, a vitamin B12 supplement may be needed for vegans.

Energy in pregnancy

Energy requirements only increase in the third trimester of pregnancy, and even then the increase is small at about 200 kcal, equivalent to one slice of wholemeal toast with peanut butter, a small handful of nuts or a portion of cereal with milk. With the majority of adult women being overweight or obese in the UK it is important to communicate that the idea of ‘eating for two’ does not stand and that it’s generally not necessary to eat more when pregnant.4

Foods to be aware of in pregnancy

There are a number of foods and drinks that should be limited or avoided in pregnancy for safety reasons (table 1). The risks associated with these foods and drinks are low and so you should reassure women that they shouldn’t be alarmed if they’ve consumed something that’s not recommended. While the list may seem long, there are plenty of alternatives that can be enjoyed and these are also given. As well as the foods and drinks to be avoided, pregnant women also need to be careful of food hygiene in general as avoiding food poisoning is particularly important in pregnancy.6

Food/drink to limit or avoid Reason What could be enjoyed instead

Cheese

Soft cheeses with rinds and soft, blue-veined cheese and all types of pate

May contain listeria bacteria Other cheeses made from pasteurised milk like mozzarella, cottage cheese, feta and cream cheese. All hard cheeses (even if blue veined) can be eaten in pregnancy. In addition the cheeses listed as ‘to avoid’ can be eaten if cooked thoroughly (steaming hot all the way through).

Milk

Unpasteurised milk or cream

May contain harmful bacteria that can cause food poisoning Standard milks and creams that have been pasteurised

Eggs

Raw or undercooked eggs that have not been produced under the ‘British Lion’ code of practice

May contain salmonella bacteria Eggs that have been produced under the British Lion code can be eaten raw or lightly cooked. This followed new safety advice from the Foods Standards Agency in 2017.

Meat

Raw, undercooked or cured meats

May contain parasites that can cause toxoplasmosis Thoroughly cooked meats, cold cooked meats and prepacked meats like ham.

Offal

Liver and pâté (all types of pâté, even fish, crab and vegetarian pâtés)

Liver and liver products may contain high levels of the retinol form of vitamin A. Pâtés may contain listeria bacteria Sliced cooked meats, dips like houmous or soft cheeses made with pasteurised milks.

Supplements

Vitamin or fish oil supplements containing vitamin A or foods fortified with vitamin A

Contain high levels of the retinol form of vitamin A Supplements designed for pregnancy containing the plant form of vitamin A (beta-carotene) can be taken and some omega 3 supplements are available that are suitable for pregnant women (vegan versions are also available).

Fish

Shark, marlin and swordfish

May contain higher levels of mercury than other fish Fish is still a good choice and should be encouraged during pregnancy*
Limit oily fish to 2 portions a week May contain low levels of pollutants  
Limit tuna to 2 fresh steaks or 4 medium-sized cans (140g drained weight) per week May contain higher levels of mercury than other fish  

Shellfish

Raw shellfish

May contain harmful bacteria that can cause food poisoning. Well-cooked shellfish are safe to eat  

Licorice

Avoid licorice root herbal remedies (moderate amounts of licorice sweets or teas can be consumed)

Contains a compound call glycyrrhizin, which may be harmful to an unborn baby Licorice sweets can be consumed but they can be high in free sugars so this should be in small amounts.

Caffeine

Limit caffeine intake to 200mg per day – equivalent to about:

  • Two cups of instant coffee (about 100mg per mug)
  • Two and a half cups of tea (about 75mg per mug)

A can of cola contains about 40mg. Energy drinks can vary in their caffeine content but a small can (250ml) can contain 80mg and a large can (500ml) 160mg.

It’s also recommended to drink herbal teas in moderation as there is little information on their safety.

Very slight risk of miscarriage with caffeine intakes above this level

 

Very high intakes of caffeine have been associated with low birthweight

Decaffeinated versions of teas, coffees and colas, and other soft drinks** can be consumed

Alcohol

Ideally avoid alcohol completely

Possible harm to baby, especially associated with heavy drinking Alcohol-free versions and other soft drinks can be consumed.
*A note on fish in pregnancy: While there are some restrictions on different types of fish it is important to remember that fish contains many beneficial nutrients and is great choice for pregnant women. The recommendation for all the population is to include two portions a week, one of which should be an oily type such as mackerel or salmon. Oily fish contributes omega 3 fatty acids that are important during pregnancy for the development of the baby’s eyes and brain. Alongside this, non-oily types and well-cooked shellfish can be consumed too and provide important nutrients like protein, iodine, selenium and B vitamins.

 

**Fizzy drinks, squashes and juice drinks can contain added sugars and very few nutrients, so should be limited.

 

Bridget Benelam is a nutritionist and nutrition communication manager at the British Nutrition Foundation

 

Resources

The British Nutrition Foundation has produced a resource to show practical ways to meet fibre needs over a day, and a FAQ resource for pregnant women on common concerns such as tiredness, constipation