Oxford Handbook of Midwifery (29 page)

1
National Institute for Health and Clinical Excellence (2008). Antenatal care: Routine care for the healthy pregnant mother. Clinical guideline 62. London: NICE. Available at: M
www.nice.org.uk/cg62.

This page intentionally left blank

Chapter 5

79‌‌

Health advice in pregnancy

Smoking
80

Alcohol
82

Nutrition during pregnancy
84

Weight gain in pregnancy and body mass index
86

Food safety
88

Folic acid
91

Iron
92

Peanut allergy
94

Exercise
96

Employment
97

Sexuality during pregnancy and beyond
98

Dealing with disability during pregnancy and beyond
102

CHAPTER 5
Health advice in pregnancy

80‌‌

Smoking

As smoking is a potentially preventable activity it is a significant public health issue in pregnancy. There are a number of risks associated with smoking during pregnancy. Although the risks are well known, many women still require specific information about the effects and support to give up or reduce the number of cigarettes smoked. It is estimated that 25% of pregnant women who smoke stop before their first antenatal appointment, and 27% of women report that they are current smokers at the time of the birth of their baby.
¹

• Cigarette smoke contains carbon monoxide and nicotine. The haemoglobin in RBCs combines with oxygen but if carbon monoxide is present this replaces the oxygen in the cell.
  
• During gaseous exchange in the placenta the oxygen levels are reduced while the cigarette is being smoked and less oxygen is transferred to the fetus.
  
• Each time a cigarette is smoked the fetus can become hypoxic.
  
• Nicotine acts on the blood vessels making them narrow. This decreases the blood flow, reducing oxygen and nutrient supply in the body.
  
• Blood vessels in the placenta will be affected at the same time reducing
  oxygen and nutrient supply to the fetus.
  

  These effects cause damage in several ways:
  

• Low birth weight due to reduced nutrition
  
• Preterm birth
  
• Stillbirth.
  

  Babies born to smokers may have the following problems:
  

• Decreased physical growth
  
• Decreased intellectual development
  
• Increased risk of sudden infant death syndrome
  
• Behavioural problems
  
• Asthma and respiratory problems
  
• Poor lung development.
  

  The mother may also experience problems during pregnancy as a result of smoking:
  

• Increased risk of early miscarriage
  
• Placental complications such as placenta praevia and placental abruption
  
• Preterm labour
  
• Intrauterine infection.
  

The midwife is in a unique position to offer information and support to the mother who smokes. If the mother is able to give up early in pregnancy she will greatly increase her chances of a delivering a healthy baby. Many localities now have a midwife dedicated to smoking cessation support and mothers can be referred to this service to receive the help they need. Women who are unable to quit should be encouraged to reduce smoking.

SMOKING

81

Women who smoke should be offered:

1
National Institute for Health and Clinical Excellence (2008).
Antenatal Care: Routine Care for the Healthy Pregnant Woman
. London: RCOG Press, p. 100.

CHAPTER 5
Health advice in pregnancy

82‌‌

Alcohol

When alcohol consumption is either occasional or moderate, it is rec- ognized as a socially acceptable behaviour. Over 90% of the population consumes alcohol, but the quantity and frequency of alcohol consumption in women of reproductive age is increasing.

The consequences of alcohol consumption on pregnancy are difficult to study, due to confounding variables such as smoking, diet, socio-economic status, and other substance misuse. The effect of alcohol consumption on the developing fetus depends on:

• The timing in relation to the period of gestation
  
• The amount of alcohol consumed.
  

  Effects can range from organ damage in the first trimester of pregnancy to growth restriction and inhibited neuro-behavioural development in the second and third trimesters.
  

  Fetal alcohol syndrome describes the complete form of the condition and has become recognized as the foremost preventable, non-genetic cause of intellectual impairment. Another term used to describe various types of this condition is ‘alcohol-related birth defects’ (ARBD).
  

  NICE
  ¹
  states that there is no conclusive evidence of adverse effects
  on either fetal growth or childhood IQ at levels of consumption below
  

  1–2 units of alcohol once or twice per week, but recommends that women should avoid alcohol if planning a pregnancy and in the first trimester.
  

  There is uncertainty about what constitutes a safe level of alcohol consumption during pregnancy but women should be informed that getting drunk, or binge drinking (5 drinks/7.5 units on a single occasion) may be harmful to the unborn baby.
  

  One unit of alcohol equates to approximately 8g of absolute alcohol. The following measures are used as guides when discussing alcohol consumption (although it is recognized that ‘home measures’ are often larger than pub measures):
  

• 1 unit alcohol = 10g alcohol
  
• 1 unit alcohol = 1 pub measure of spirits
  
• 1 unit alcohol = ½ pint ordinary strength beer/lager
  
• 1 unit alcohol = 1 small glass red or white wine.
  

1
National Institute for Health and Clinical Excellence (2008).
Antenatal Care: Routine Care for the Healthy Pregnant Woman
. London: RCOG Press, p. 99.

This page intentionally left blank

CHAPTER 5
Health advice in pregnancy

84‌‌

Nutrition during pregnancy

Good nutrition is essential for a successful and healthy pregnancy, as poor nutrition is associated with adverse pregnancy outcomes. Increases in specific nutrients are recommended during pregnancy, but these are not difficult to attain in a well-balanced diet. The estimated average require- ment (EAR) for energy during pregnancy is 2000kcal/day in the last tri- mester only,
¹
therefore it is not necessary for a woman to ‘eat for two’. Nutritional requirements also vary due to changes in basal metabolic rate, which varies widely, increasing in some women and decreasing in others.

Calcium

Calcium needs are highest during the last trimester. Calcium absorption is more efficient during pregnancy but it is still important to eat plenty of calcium-rich foods. The best sources are dairy products such as milk, cheese, yoghurt, dark-green vegetables, sardines, pulses, tofu, nuts, and seeds.

Iron

Iron is needed by the fetus and mother as a reserve for blood loss during
pregnancy. Needs are normally met by an increase in absorption and absence of menstruation. Good maternal iron stores and a good dietary

intake are needed throughout pregnancy. Lean red meat, chicken to a lesser extent, and fish are the best sources. Iron from animal sources is better absorbed than that from green vegetables, fortified breakfast cereals, bread, pulses, and dried fruit. Vitamin C helps the absorption of iron if taken at the same time.

Zinc

Zinc is involved in over 200 enzyme reactions in the body, including a key role in stabilizing the structure of DNA and RNA, therefore in conjunc- tion with folic acid it helps to prevent neural tube defects. It is also an important mineral for fertility in both men and women. Although zinc is widespread in many foods it may be deficient in some diets due to a high consumption of highly processed foods.

Essential fatty acids

Essential fatty acids are particularly important during periods of rapid fetal brain growth and in early neonatal life. During pregnancy they are respon- sible for the production of prostaglandins and steroid hormones. Dietary sources include vegetable oils, oily fish (mackerel, tuna, and sardines) and lean red meat.

Vitamin D

Vitamin D is produced within the skin in response to sunlight. The majority of women have no difficulty in maintaining their own vitamin D levels but for vulnerable groups which include women whose cultural practices include covering the head and body, vitamin D synthesis may be reduced. For these women a 10micrograms/day supplement is recommended.

NUTRITION DURING PREGNANCY

85

Vitamin B
₁₂

Vitamin B
₁₂
stores are not usually depleted as a result of pregnancy and lactation, but they can be impaired in vegetarians as vitamin B
₁₂
is exclusively of animal origin. Vitamin B
₁₂
levels can be maintained by con- suming fortified products such as Marmite
^®
, breakfast cereals, and soya products.

1
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.

CHAPTER 5
Health advice in pregnancy

86‌‌

Weight gain in pregnancy and body mass index

Weight gain during pregnancy is extremely variable and can be influenced by factors such as maternal age, parity, BMR, diet, smoking, pre-pregnancy weight, size of the fetus, and maternal illness such as diabetes. The weight gain is distributed between the fetus, placenta, membranes, amniotic fluid, and the physiological development of maternal organs, e.g. uterus and breasts (blood and fat deposition in preparation for lactation). Most healthy women in the UK gain between 11 and 16kg, although young mothers and primigravidae usually gain more than older mothers and multigravidae.
¹

An optimal weight gain of 12.5kg is the figure used for an average pregnancy. This is associated with the lowest risk of complications during pregnancy and labour and of low birthweight babies.
²
Maternal weight gain tends to be more rapid from 20 weeks onwards, although excessive weight gain during pregnancy is associated with postpartum weight retention, as is increased weight gain in early pregnancy compared with late pregnancy. Weight gains above 12.5kg in women of normal pre-

pregnancy BMI are unlikely to reflect an increase in fetal weight, maternal lean tissue, or water.

Perinatal outcome has a complex relationship with maternal pre- pregnancy BMI, as well as with antenatal weight gain. Calculating the BMI is a method of estimating the amount of body fat, based on weight and height. The index is calculated by dividing the individual’s weight in kilograms by the square of his or her height in metres. Many charts are available for instant grading (Table 5.1).