Oxford Handbook of Midwifery (18 page)

Examples

When calculation is difficult

• Combined oral contraception, ‘the pill’, may confuse withdrawal bleeding with a normal period; anovular cycles may lead to inaccuracy in calculation of expected birth date.
  
• Cerazette
  ^®
  progesterone-only pill may have the same effect—it is designed to inhibit ovulation, unlike other progesterone-only pills.
  
• After Depo-Provera
  ^®
  injections it may take several months before menstrual bleeding and ovulation return; anovular cycles may lead to inaccuracy in calculating the expected birth date.
  
• After the removal of the Mirena
  ^®
  intrauterine system or an Implanon
  ^®
  or Nexplanon
  ^®
  implant, the woman’s hormonal levels return to normal with 72h of removal and will not inhibit early conception.
  
• A copper intrauterine device does not affect the woman’s hormonal levels.
  

  1
  Nguyen T, Larsen T, Enghollm G,
  et al
  . (1999). Evaluation of ultrasound-estimated date of delivery in 17,450 spontaneous singleton births: do we need to modify Naegele’s rule?
  Ultrasound in Obstetrics and Gynaecology
  14
  (1), 223–8.
  

  CHAPTER 2
  Pre-conception care
  

  18‌‌
  

  Nutrition
  

  For women of childbearing age, the estimated average requirement (EAR) for energy is approximately 2000kcal/day. A healthy diet contains a variety of foods including protein and starchy carbohydrates such as bread, break- fast cereals, potatoes, pasta, rice, and a daily helping of at least five fruits or vegetables. Foods containing excess fat should be used sparingly and foods containing sugar should be eaten infrequently, in small amounts. (b See also Chapter 4.)
  

  Good nutrition is an essential requirement to a successful outcome of pregnancy. In the ideal situation, the woman will have good body stores of the vitamins and minerals the embryo requires in order to develop into a healthy fetus. Poor nutritional status can cause problems with fertility and conception, and the extremes of body weight, e.g. being underweight or very overweight, are associated with adverse pregnancy outcomes,
  

  such as low birthweight, or developing complications of pregnancy such
  

  as high blood pressure, gestational diabetes, and preterm labour. Women in these categories are advised take steps to modify their body weight towards the normal range in preparation for pregnancy.
  

  Other categories of women who may be in need of nutritional counselling include:
  

  • Those with
    closely spaced pregnancies.
    If the gap between births is only about 1 year, there is an increased risk of the next baby being born prematurely and/or of low birthweight. Two or three years between births allows the repletion of body stores. Until then, vitamin and/or mineral supplements may be appropriate.
    
  • Vegans/vegetarians
    . These diets can be extremely healthy; however, if meat or fish or dairy foods are avoided, essential nutrients must be
    

    replaced from other food sources, such as cereals and pulses, nuts, and seeds. Yeast extracts, such as Marmite
    ^®
    , are fortified with vitamin B
    ₁₂
    .
    

  • Adolescents
    . A main influence on pregnancy outcome is the number of years between the menarche and pregnancy: the shorter this interval, the greater the potential for nutritional deficiencies. Nutritional deficiencies are also more likely during pregnancy as adolescents need enough nutrients to complete their own growth as well as to fulfil the demands of a growing baby.
    
  • Those with
    a low income
    . Several surveys have shown that women tend to ‘go without’ food themselves in order to ensure that other members of their family get enough to eat.
    ¹
    
  • Those with
    a pre-existing disease
    , e.g. diabetes and epilepsy. Food allergies should always be diagnosed medically, and malabsorption syndromes, such as Crohn’s disease, ulcerative colitis, or cystic fibrosis, require dietetic consultation.
    

  NUTRITION
  

  19
  

1
Northwest Community Hospital (1995).
Going Hungry: The Struggle to Eat on a Low Income
. Available at: M
www.nch.org/uploads/documents/going-hungry.pdf (accessed 20.3.10).

CHAPTER 2
Pre-conception care

20‌‌

Lifestyle

Changes in lifestyle

A person’s lifestyle can impact on their health and well-being and a healthy lifestyle is the ideal for everyone. It is even more appropriate during preg- nancy to consider the impact of lifestyle choices. Couples who are plan- ning a pregnancy may seek advice prior to conception.

The aim of pre-conception care is to prepare the body for a successful pregnancy. This preparation should take place at least 3–4 months prior to conception. The following lifestyle changes may be suggested:

• Advise the woman and her partner to give up smoking, as women who smoke reduce their chance of a successful pregnancy by 40% compared with non-smokers. Smoking reduces sperm motility and can
  

  lead to higher numbers of abnormal sperm. Offer referral to a smoking
  cessation programme (NHS smoking helpline is 0800 169 0169).
  

• Advise a reduction or elimination of alcohol from the diet. Women
  

  who drink more than 10 units per week have a reduced chance of successful pregnancy and increased risk of miscarriage compared with women who drink fewer than 5 units per week. Excess alcohol
  

  consumption by the mother is associated with fetal alcohol syndrome.
  

• Advise the woman to avoid using illegal drugs and if she is taking prescribed medications to ask for her general practitioner’s (GP’s) advice.
  
• Some occupations may reduce male and female fertility. Exposure to heat, X-rays, chemical pesticides, or solvents may contribute to reduced fertility. Advise avoiding such exposure as far a possible.
  
• If the man or woman is obese, advise weight reduction prior to pregnancy as excessive weight reduces fertility in both men and women, and the woman is at a greater risk of pregnancy and delivery complications.
  

  Medical considerations
  

• The woman can be offered a blood test to determine her rubella immune status and offered vaccination 3 months prior to pregnancy if she is not immune. The vaccination can also be offered after the birth although there is no indication that the vaccine is teratogenic.
  
• Perform a full blood count to screen for anaemia, which can be corrected prior to pregnancy.
  
• Measure blood pressure to screen for hypertension.
  
• Perform a cervical smear test if more than 5 years have elapsed since her last test.
  
• Test a urine sample for the presence of protein (indicator of renal disease or infection) and glucose (indicator of diabetes).
  
• Offer the couple screening for genital infection as many of these are asymptomatic.
  

MEDICAL CONDITIONS

21‌‌

Medical conditions

Certain medical conditions may complicate pregnancy, and women who have these should be referred to their GP before embarking on a preg- nancy so that any concerns can be addressed, medications reviewed, and treatment adjusted to enable a successful pregnancy to be achieved.

Type 1 diabetes