Alison Morton and Helen White. Jan, 2001. Preconceptional nutrition [online]. Seacroft and St James's University Hospitals, Leeds, UK. Available from http://www.cysticfibrosismedicine.com

Introduction: Women with cystic fibrosis can have a successful pregnancy without compromising long-term nutrition or pulmonary function (Olsen 1997). Nutritional status plays an integral role in the pre-conceptional period and throughout the pregnancy. When a woman is planning a pregnancy she should first discuss this with her CF consultant, he/she will rationalise medication as appropriate. At this time a thorough nutritional assessment by the CF specialist dietitian should be carried out. This includes:

Weight, height and body mass index (BMI)

Four day dietary diary (for computer analysis)

Review of enzyme therapy

Review of diabetic status with probable conversion to insulin for those on oral hypoglycaemic agents (CF Consultant or Endocrinologist/Diabetologist)

Optimise glycaemic control

Measurement of fasting vitamins A, D and E

Review of vitamin therapy (including non-prescription items)

Dietary advice is then based upon the results of the dietary assessment and targets

Optimising nutritional status: A low preconceptional weight is a risk factor for poor pregnancy outcome in any pregnancy. A body mass index of 24 has been suggested as optimal for conception in the non-CF population (Wynn and Wynn 1990). Optimising nutritional status in the pre-conceptional period is of paramount importance in women with CF. Patients are advised to eat a healthy high energy diet with dietary advice being tailored for the individuals dependant on weight/BMI, daily meal pattern, quantitative and qualitative analysis of intake and nutritional requirements. Where possible food items such as butter, cream, cheese, sugar, jams are used to increase the energy density of the diet. High calorie snacks eg crisps, nuts, chocolate may be encouraged. If necessary appropriate oral nutritional supplements or invasive nutritional support may be discussed/introduced.

Vitamin supplements: Research has shown that increasing a woman’s folic acid intake in the pre-conceptional period and during the first timester may prevent neural tube handicaps/defects. All women who are planning a pregnancy should take a daily supplement of 400mcg of folic acid from the time they plan their pregnancy and throughout the first trimester. If a pregnancy is unplanned folic acid should be started as soon possible until the twelfth week of the pregnancy. Folic acid is a water-soluble B vitamin, which occurs naturally in food in the form of folates. It is also used to fortify bread and some cereal products. Cooking may cause a reduction in the folate content of foods as heat can destroy them and they may also dissolve into the cooking water. Dietary advice should be aimed at: A) Increasing the understanding of the importance of folic acid supplementation for the health and development of the baby. Identifying foods fortified with folic acid eg breakfast cereals and some breads and encouraging their intake. B) Encouraging the patient to eat foods high in folic acid or folates eg Brussel sprouts, beef and yeast extracts, green leafy vegetables eg kale, spinach, spring greens, broccoli; oranges and orange juice, beans and pulses such as baked beans, black eyed beans, soya beans, chick peas. NB Liver and liver products are rich in folic acid but these are not encouraged in pregnancy due to the possible teratrogenic effect of excess vitamin A.

Vitamins A, D and E: Most patients with CF will be taking vitamin supplements of the fat-soluble vitamins A D and E. Vitamin D is essential in pregnancy when the requirement for this vitamin is increased. Very high intakes of vitamin A (<10,000 IU/day) have been associated with an increased incidence of birth defects in the non-CF population. Women in the UK who are or might become pregnant have been advised not to take supplements containing vitamin A unless advised to do so by a Doctor (DOH 1990). Serum levels of vitamin A should be checked in the pre-conceptional period or at the start of pregnancy. If levels are low or normal it would appear advisable to continue Vitamin A supplementation at a dose of less than 10,000 IU/day (usually 8000IU). Reassurance is essential for the patient.

Other vitamins: It is essential to review all non-prescription, over the counter and herbal vitamins/products which patients may be taking.

Food safety: In addition to the nutritional aspects of the diet it is important to provide advice regarding avoidance of possible infections eg listeriosis, toxoplasmosis, salmonellosis which may be harmful to the unborn child. The Department of Health provide useful/supportive literature.

Listeriosis: Listerosis is caused by a bacterium called Listeria monocytogenes. Listeriosis is very rare and in 1990 it affected approximately 1 in 30,000 pregnancies. In the mother it causes only a mild flu like illness but if the mother becomes infected it can result in miscarriage, stillbirth or severe illness in the newborn baby. To avoid the risk of infection pregnant women are advised to avoid ripened soft and blue veined cheeses.

Cheeses to avoid: Ripened soft cheeses: Brie, Cambozola, Camembert, Chaumes, Lymeswold, Pont L’Evenque, Tallegio Blue veined cheeses: Bavarian Blue, Blue Brie, Blue Shropshire, Danish Blue, Dolcelatte, Gorgonzola, Roquefort, Stilton, Stilton spread cheese. There is no need to avoid hard cheese, cottage cheeses or processed cheeses. Cheeses which are safe to eat: Hard cheeses: Austrian Smoked, Babybel, Caerphilly, Cheddar, Cheshire, Derby, Edam, Emmental, English goat’s cheddar, Feta, Glucester, Gouda,Gruyere, Halloumi, Havarti, Jarlsberg, Lancashire, Leicester, Mozzarella, Orkneu, Paneer, parmesan, Pecorino (hard), Provolone, Port Salut, Wensleydale. Soft and processed cheeses: Cottage, spread, processed cream and processed cheeses, Borsin, Mascarpone, Philadelphia, Quark, Ricotta. Yogurts, fromage frais, soured cream (crème fraiche): Any variety ie natural, flavoured and whether biologically active or not, are safe to eat.

Toxoplasmosis: Toxoplasmosis is an illness caused by an organism Toxoplasma gondii which has been found in raw meat and cat faeces. It does not usually cause any problems though it can cause flu-like symptoms and in severe cases an illness similar to glandular fever. In most cases a person does not realise they have ever had it. Some pregnant women will have had toxoplasmosis in the past – the risk to the baby is only from an infection caused during pregnancy or shortly before conception. Toxoplasmosis in pregnancy can result in miscarriage, stillbirth or severe illness (brain damage/blindness). Toxoplasmosis is extremely rare and affects approximately 1 in 50,000 pregnancies.

Salmonellosis: Salmonella is one of the most common causes of food poisoning. Although salmonellosis may not have a direct effect on the unborn baby, it is sensible to avoid this illness during pregnancy. Salmonella is particularly associated with chicken and raw eggs. To reduce the possibility of becoming infected with these or other food born organisms it is important to follow these guidelines:

Food safety guidelines. Always wash hands thoroughly before and after preparing food. Use one board for preparing raw meat and poultry and a separate board for other foods. Wash hands, all boards, cooking utensils and surfaces after preparing raw meat. Make sure raw food does not contaminate other food. Store raw meat and poultry on the bottom shelf of the fridge so blood and juices do not drip on other foods. Use a thermometer to ensure the fridge is kept below 5°C and freezer below – 18°C. Defrost frozen meat and poultry thoroughly before cooking. Follow the manufacturers cooking instructions precisely. Do not eat food which has passed the manufacturers “use by” date. Cook meat and poultry thoroughly and ensure all food is piping hot throughout. Avoid raw and uncooked meats eg Parma ham, Steak tartare, Salami. Thoroughly reheat cook chill foods and ready cooked poultry dishes. Avoid raw eggs and foods containing them eg home made mayonnaise, mousses etc. Only eat eggs which are cooked until both the yolk and white are solid. Avoid “green top” milk (unpasteurised) unless it has been boiled for at least two minutes. Avoid unpasteurised sheep and goats milk and cheese made from unpasteurised milks. Avoid meat, fish and vegetable pates unless tinned or marked pasteurised. Avoid shellfish eg prawns, mussels, cockles unless packaged and clearly marked with a use by date. Avoid soft-whip ice cream from machines. Use caution when buying unwrapped foods eg salads, cooked meats. Avoid infections from other sources. Wear rubber gloves whilst gardening and always wash your hands thoroughly afterwards. Wear rubber gloves when emptying cat litter trays – wash your hands and the gloves afterwards. Wash your hands after handling kittens or cats. Do not use the same utensils and bowls for pet food and your own food. Wash pet dishes separately. Avoid milking ewes that have recently given birth, lambing and all contact with newborn lambs.

Alcohol: Advice regarding alcohol consumption is also provided. Pregnant females should aim to reduce their alcohol intake. The recommendations are to limit alcohol intake to no more than eight units of alcohol per week and no more than two units at any one time. 1 Unit of Alcohol = 1 pub measure of spirit = ½ pint beer or lager = 1 glass wine = ½ bottle of alco pop.

References

Olsen G. Cystic Fibrosis In Pregnancy. Seminars In Perinatology 1997; 21 (4): 307-12

Wynn A, Wynn M. The Need For Nutritional Assessment In the Treatment Of The Infertile Patient. J Nutr. Med 1, 315-24

Chief Medical Officer. Department Of Health Press Release No 90/507 Women Cautioned – Watch Your Vitamin A Intake. London Department Of Health, 1990

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