Oxford Handbook of Midwifery (30 page)

Table 5.1
Grading of weight by BMI

BMI Interpretation

<20 Underweight

20–24.9 Desirable

25–29.9 Overweight

>30 Obese

Appropriate weight gain for individual women should be based on their pre-pregnancy BMI (Table 5.2), as lower perinatal mortality rates are associated with underweight women who achieve high weight gains and overweight women who achieve low gains. The number of women in the obese category of BMI is escalating and rapidly becoming a major public health problem within maternity care.
³
Maternal and perinatal complica- tions are much more prevalent, such as an increased risk of gestational diabetes, pre-eclampsia, macrosomia, and perinatal mortality.
^3,4

WEIGHT GAIN IN PREGNANCY AND BODY MASS INDEX

87

Table 5.2
Weight gain in pregnancy and BMI

Pre-pregnancy body mass index [weight (kg)/height (m
²
)]

Recommended weight gain kg lb

Low (<19.8) 12.5–18.0 28–40

Normal (19.8–26) 11.5–16.0 25–35

High (26.0–29.0) 7–11.5 15–25

Obese (>29)
¹
6 (min.) 14 (max.)

Recommended reading

Webster-Gandy J, Madden A, Holdsworth M (2006).
Oxford Handbook of Nutrition and Dietetics
. Oxford: Oxford University Press.

1. Hytten FE (1991). Weight gain in pregnancy. In Hytten FE and Chamberlain G (eds)
   Clinical Pathology in Obstetrics
   . London, Blackwell Scientific: 173–203.
   
2. Goldberg GR (2000). Nutrition in pregnancy.
   Advisa Medica
   , London,
   1
   (2): 1–3.
   
3. Veerareddy S, Khalil A, O’Brien P (2009). Obesity implications for labour and the puerperium.
   

   British Journal of Midwifery,
   17
   (6): 360–362.
   

4. Stewart FM, Ramsay JE, Greer IA (2009). Obesity: impact on obstetric practice and outcome.
   

   Obstetrician and Gynaecologist
   ,
   11
   (1): 25–31.
   

   CHAPTER 5
   Health advice in pregnancy
   

   88‌‌
   

   Food safety
   

   Listeriosis
   

   Listeria monocytogenes
   is a Gram-positive bacterium that is normally found in soil and water, on plants, and in sewage. The incidence of listeriosis in adults is 0.5:100 000 and the mortality rate is about 26% in vulnerable groups such as babies, the elderly, immunocompromised individuals (such as those with acquired immune deficiency syndrome (AIDS)), and during pregnancy. Infection is usually asymptomatic in healthy adults.
   

   Currently it is thought to affect approximately 1 in 20 000 pregnancies and, due to the suppressed immune response in pregnancy, the bacteria can cross the placenta. Infection during pregnancy is serious and can lead to spontaneous abortion, stillbirth, preterm labour, congenital infection, or infection after birth. Affected babies often develop pneumonia, septicaemia, or meningitis, depending on when the infection occurred. Case studies of pregnancies complicated by listeriosis report a history of having had a flu-like illness up to 2 weeks before the onset of labour, and of eating soft French cheeses, pre-packaged salads, or pre-cooked chicken.
   

   Advice from the Department of Health
   ¹
   for vulnerable groups includes the following:
   

   • Avoid mould-ripened cheeses, such as Brie and Camembert, and blue- veined cheeses, such as Danish Blue or Stilton.
     
   • Avoid meat, fish, or vegetable pâté, unless it is tinned or marked pasteurized.
     
   • Thoroughly re-heat cook-chill foods and ready-cooked poultry.
     

Toxoplasmosis

Toxoplasmosis is an infection caused by the parasite
Toxoplasma gondii
, a microscopic, single-celled organism that can be found in raw and inad- equately cooked/cured meat, cat faeces, the soil where cats defecate, and unpasteurized goats’ milk. Infection is often asymptomatic, although if symptoms do present, they are of a mild flu-like illness. Infection produces lifelong immunity. It is predicted that 30% of people will have had toxo- plasmosis by the age of 30 years.

Vulnerable groups are babies, the elderly, immunocompromised individuals, and pregnant women. The risk of vertical transmission ranges from 15% in the first trimester to 65% in the third trimester.
²
If the infection is contracted during the first trimester of pregnancy, then severe fetal damage is likely and may result in miscarriage or stillbirth. If it is contracted during the third trimester, then the risk of the fetus being infected is higher. Babies with congenital toxoplasmosis may develop encephalitis, cerebral calcification, convulsions, and chorioretinitis.

Immune status can be determined by serological screening, although routine testing in the UK is not offered, as it is predicted that 80% of women would be negative.
³
If infection during pregnancy is suspected, blood tests for antibodies will be able to detect whether the infection is recent, and amniocentesis or cordocentesis will determine whether the fetus is affected. Management may include antibiotic therapy. Termination of

FOOD SAFETY

89

pregnancy may be offered when there is evidence of fetal damage or infection.

Avoiding the infection is the simplest and best way to prevent congenital toxoplasmosis; therefore the following advice should be given to pregnant women:

There is no contraindication to breastfeeding by a woman who has, or is undergoing treatment for, toxoplasmosis.

Vitamin A

Vitamin A is a fat-soluble vitamin that is essential for embryogenesis, growth, and epithelial differentiation. The retinol form of vitamin A is found chiefly in dairy products such as milk, butter, cheese, and egg yolk, some fatty fish, and in the liver of farm animals and fish. Experiments in animals have shown that retinoids, but not carotenoids, can be teratogenic.
⁴

A high dietary intake of vitamin A before the seventh week of pregnancy has produced an increased frequency of birth defects, including cleft lip; ventricular septal defect; multiple heart defects; transposition of the great vessels; hydrocephaly; and neural tube defects.

Retinol is given to animals as a growth promoter, and any excess is stored in the liver. Since 1990, women who are pregnant or planning a pregnancy have been advised to avoid eating liver and liver products such as pâté or liver sausage, as they contain large amounts of retinol.

Vitamin A deficiency is largely a problem of developing countries, and is relatively uncommon in the developed world in the absence of disease. In the UK, the reference nutrient intake (RNI) is 600micrograms/day, with a 100micrograms/day increase during pregnancy.
⁵
Most women in the UK have a vitamin A intake in excess of the RNI.

Cod liver oil supplements may contain large amounts of vitamin A and should not be taken during pregnancy, except on medical advice.

Caffeine

Caffeine is a methyl xanthine, a naturally occurring compound found in plants. It is present in tea, coffee, and chocolate, and acts as a stimulant. It is also added to some soft drinks and so-called ‘energy’ drinks, as well

CHAPTER 5
Health advice in pregnancy

90

as over-the-counter anti-emetics and analgesics.
⁶
In pregnant women it is metabolized more slowly, and studies have suggested an association between the ingestion of caffeine and an increased risk of spontaneous abortion.
⁷
During breastfeeding an excessive intake can cause irritability and sleeplessness in both the mother and the baby.

The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment looked at the effects of caffeine on reproduction, and concluded that caffeine intakes above 200mg/day may be associated with low birthweight and, in some cases, miscarriage. Therefore, the Food Standards Agency
⁸
has issued advice to pregnant women to limit their intake of caffeine to less than the equivalent of two mugs of coffee a day.

It is not necessary for women to cut out caffeine in the diet completely, but it is important that they are aware of the risks, so they can ensure that they do not have more than the recommended amount. 200mg of caffeine is roughly equivalent to:

• 2 mugs of instant coffee (100mg each)
  
• 2½ cups of instant coffee (75mg each)
  
• 2 cups of brewed coffee (100mg each)
  
• 4 cups of tea (50mg each)
  
• 3 cans of cola (up to 80mg each)
  

  •
  4 (50g) bars of chocolate (up to 50mg each).
  

  1. Food Standards Agency (2007). Your questions answered: listeriosis. Available at: M www.food.
     gov.uk/multimedia/faq/anchorcatering (accessed 3 November 2009).
     
  2. Tommy’s The Baby Charity (2001).
     Toxoplasmosis: A Hand Book for Health Professionals
     . London: Tommy's. Available at: M
     www.tommys-campaign.org/problems/ToxoAcquired.pdf (accessed 2.3.10).
     
  3. Elsheikha HM (2008). Congenital toxoplasmosis: priorities for further health promotion action.
     

     Public Health
     122
     (4), 335–53.
     

  4. Azais-Braesco V, Pascal G (2000). Vitamin A in pregnancy: requirements and safety limits.
     

     American Journal of Nutrition
     71
     (55), 13255–335.
     

  5. Department of Health (1991).
     Report on Health and Social Subjects 41. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Dietary Reference Values for the United Kingdom
     . London: HMSO.
     
  6. Jordan S (2002).
     Pharmacology for Midwives The Evidence Base for Safe Practice
     . Hampshire: Palgrave, p. 18.
     
  7. Cnattingius S, Signorello LB, Anneren G,
     et al.
     (2000). Caffeine intake and the risk of first- trimester spontaneous abortion.
     New England Journal of Medicine
     343
     (25), 1839–45.
     
  8. Food Standards Agency (2008).
     Advice for Pregnant Women on Caffeine Consumption
     . London: FSA. Available at: M
     www.food.gov.uk/news/pressreleases/2008/nov/caffeineadvice (accessed 3 November 2009).
     

  FOLIC ACID
  

  91‌‌
  

  Folic acid
  

  Folic acid is a water-soluble B vitamin that is necessary for DNA synthesis and has a key role in cell division and development. Folates are folic acid derivatives found naturally in foods. The richest sources are leafy green vegetables, potatoes, and other vegetables and pulses. Liver is one of the richest sources of folate but should not be consumed in pregnancy due to high levels of vitamin A (b see Food safety, p. 88). A diet that is rich in other B vitamins and vitamin C is usually rich in folates. Folates are rapidly destroyed by heat and dissolve readily in water, therefore considerable losses can occur during cooking, keeping foods warm, and prolonged storage. Deficiency of folate can result in a megaloblastic or macrocytic anaemia, either through inadequate intake, malabsorption, or increased requirements, as in pregnancy or drug treatments with anticonvulsants and oral contraceptives. Requirements are increased in pregnancy due to increased cell turnover, and are particularly important around the time of conception and during early pregnancy.
  

  The RNI for folate is 200micrograms/day for both males and females from the age of 11 years onwards. The Expert Advisory Group on Folic Acid and Neural Tube Defects (NTDs)
  ¹
  recommended that to reduce
  

  the risk of first occurrence of NTDs, women should increase their daily
  

  folate and folic acid intake by an additional 400micrograms (making a total of 600micrograms/day) prior to conception, or from the time they stop using contraception, and during the first 12 weeks of pregnancy. This can be achieved by: