Food-related risks in pregnancy

It's so important to eat enough good food to satisfy your nutritional needs while you're pregnant or you could put yourself and your developing baby at risk.

Fresh food rather than processed is best. Take care not to eat food contaminated with bacteria that cause disease; for example, chicken or eggs contaminated with salmonella.

Malnutrition in pregnancy

You need to eat properly for your baby's sake. If you don't, there's a higher risk you could miscarry or have a premature or low birthweight baby, who will be more vulnerable at birth and later in life. (By the way, having a low birthweight baby does not mean labour will be easier.) Being poorly nourished yourself can also slow the growth of the placenta, and low placental weight is related to a higher infant mortality rate. Your baby's brain develops most rapidly in the last trimester of pregnancy (and in the first month of life after birth) so if you're undernourished it can affect your baby's brain function.

A poor diet during pregnancy can continue to affect a child throughout his life, and may mean he's more likely to suffer such middle-aged diseases as high blood pressure, coronary artery disease, and obesity. If there's not enough nutrition getting through to your womb, the baby diverts what's available to those cells that are immediately important, and away from those cells that will not be important until later in life - in effect, your unborn baby trades long life for survival.

On the other hand, if you have enough good food and give birth to a good-sized baby, such a baby will be easier to care for, more vigorous, active, and mentally alert, and less likely to suffer from colic, diarrhoea, anaemia, and infection. If you're on a low income and you can't afford what you need, ask your midwife about free vitamin supplements.

Processed foods

Many of these foods contain chemicals to improve flavour and shelf life. As a general rule, it's best to avoid these, especially when you're pregnant - in particular, processed cheese and meats, cheese spreads, and sausages. Check the lists of ingredients on labels for additives - food colourings and preservatives are represented by E numbers. Always make sure that you eat any packaged food well before its use-by date. Avoid highly salted foods, particularly if they contain monosodium glutamate (MSG), which causes dehydration and headaches.

Preserved foods such as smoked fish, meat, and cheese, pickled food, and sausages often contain nitrates. These can react with the haemoglobin in your blood and reduce its oxygen-carrying power so are best avoided.

Drinks

Caffeine (in tea, coffee, and chocolate) is a stimulant, so try to cut it down when you're pregnant. The tannin in tea interferes with iron absorption: drink organic herbal teas instead. Soft drinks always contain sugar or sweeteners, so limit your intake of them. Mineral water is fine.

Food hazards

Some foods can be contaminated with large enough numbers of bacteria to cause illness, particularly in vulnerable people - such as pregnant women and babies.

Listeriosis in pregnancy

Foods that can contain large numbers of listeria bacteria include soft cheese, unpasteurized milk, ready-prepared coleslaw, cooked chilled foods, pâtés, and meat that hasn't been properly cooked. Listeria bacteria are normally destroyed at pasteurizing temperatures, but if infected food is then refrigerated, the bacteria may continue to multiply. For this reason, you shouldn't eat chilled food after the “use-by” date. Listeriosis can spread through direct contact with infected live animals, such as sheep. Symptoms are flu-like: a high temperature and aches and pains, and also sore throat and eyes, diarrhoea, and stomach pain. An unborn child affected through his mother's blood may be stillborn, and listeriosis may be a cause of recurrent miscarriage.

Salmonella in pregnancy

Infection with salmonella is often traced to eggs and chicken meat, so avoid any foods that contain raw eggs, and cook eggs and chicken thoroughly. Choose free-range poultry and look for eggs with the Lion Quality mark, which means they have been produced to the highest standards of food safety.

Symptoms of salmonella, including headache, nausea, abdominal pain, diarrhoea, shivering, and fever, develop suddenly 12-48 hours after infection and last about two to three days. If the infection spreads into your bloodstream, you'll need to take antibiotics.

Toxoplasmosis in pregnancy

This common infection can be picked up by eating raw or undercooked pork or beef, or by coming into contact with the faeces of infected cats and dogs (see Toxoplasmosis and your baby).

Dysentery in pregnancy

This is carried in the faeces of an affected person. It causes dehydration, severe diarrhoea, and abdominal pain and is dangerous for pregnant women. Amoebic dysentery is rare outside tropical areas, but bacterial dysentery is more common. It's usually passed on when an infected person fails to wash his hands properly after going to the toilet and then handles food.

Are you at risk nutritionally?

• If you've had a recent stillbirth or miscarriage, or you're having a baby soon after a previous child (at least 18 months between babies is best for your health).

• If you smoke, or drink alcohol heavily.

• If you're allergic to certain foods, such as cow's milk or wheat.

• If you suffer from a chronic medical condition that means you have to take long-term medication.

• If you're under 18, your own body is growing quickly and your nutritional needs will be higher than average when pregnant.

• If you're carrying twins or multiple babies.

• If you've been under a lot of stress or had any physical injury.

• If your job involves physical work or is in a potentially dangerous environment (see Avoiding Hazards).

• If you were generally run-down or underweight before conception, or eating an inadequate or unbalanced diet.

• If you are bulimic, anorexic, or have a BMI (body mass index) of less than 19.

Food safety

• Always use clean utensils between jobs, or tastings.

• Always wash hands after going to the lavatory and before touching food, and take good care to seal off any infections or cuts.

• Defrost and cook food thoroughly, especially poultry

• Never let raw meat or eggs come into contact with other foods.

• Avoid dented and rusty tins and any food that looks or smells “off”.

• Make sure dairy products have been pasteurized.

• Don't refreeze food that has already been defrosted.

• Reheat food thoroughly and only once. Throw away leftovers.

• It's important to wash all salad leaves under cold running water - even salad marked washed and ready to eat.

Dr Miriam Stoppard

Conception Pregnancy and Birth
Copyright © 2008 Dorling Kindersley
Text copyright © 2008 Miriam Stoppard

Posted 16.11.2010

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