Chapter Eight. Preconception matters
Introduction
In addition to the purpose of preconception care, this chapter is concerned with the extent to which childbearing can be affected by the lifestyle of individuals and the environment in which they live, as well as with certain interventions and the main challenges in the process of prepregnancy care provision. Concepts from the disciplines of ecology and evolution will be utilised to discuss the implications of radiation, toxic waste and drug ingestion and their interaction with the physiology of conception.
The problems caused by pregnancy-induced disorders are considerable; Moore & Persaud (2008) estimate that between 7% and 10% of birth defects result from the ‘disruptive actions of drugs, viruses and other environmental factors’. There are also many cases of multifactorial inheritance where genetic and environmental factors act together in complex ways.
Prepregnancy care provision
A difficulty inherent in the concept of preconceptual care for health professionals is that one-third to half of all babies are conceived accidentally. For most of those who plan their conception, by the time their pregnancy is confirmed, many embryonic organs have been developing and this is the most vulnerable stage of embryogenesis. Embryogenesis is completed by the eighth week of pregnancy and few women attend for their first antenatal visit that early in pregnancy. It is then too late for early preventative strategies such as folic acid intake for elimination of neural tube defects. Ethical considerations limit the conduction of randomised trials to investigate efficacy of preconception counselling. Nevertheless, there is evidence from retrospective, prospective and case control studies to indicate that preconception counselling improves pregnancy outcome.
There has been a progressive reduction in perinatal mortality in the last century, but there should be greater emphasis on prepregnancy care and counselling to reduce these low rates of mortality (Smith 1992) and to minimise perinatal morbidity further. Research suggests that pregnancy outcome is improved markedly when couples are screened and advised prior to conception (Korenbrot et al 2002). The mother’s diet and possibly the father’s also, immediately prior to and at the time of conception, may influence the developing embryo. There is evidence from animal studies that spermatogenesis is influenced by diet (Smith & Akinbamijo 2000). There are debates concerning appropriate location, timing and format of preconception care provision, and it has been suggested that young girls or women of childbearing age should be opportunistically educated at school or in primary care settings.
Aims of prepregnancy care
Because of the high level of unplanned pregnancies, preconception care should be embraced in the health education of schoolchildren, continued into adult life and special programmes established that are targeted at groups most in need, such as people in lower social class, smokers, obese women or those at high risk of complications (diabetes or epilepsy). The aims of prepregnancy care according to Chamberlain (1992) are:
• To provide the means of ensuring that preventable factors are attended to before pregnancy starts—e.g. rubella inoculation.
• To give advice about the effects of pre-existing disease and its treatment on the pregnancy and unborn child.
• To consider the likelihood and effects of any recurrence of events from previous pregnancies and deliveries.
Chronic diseases
The benefits of preconception care are more evident in pre-existing and chronic diseases. Chapple (2007) identifies certain groups of women who are particularly in need of preconception care and emphasises the importance of a sensitive approach when dealing with them. In addition to their own concerns, they may be fearful of health care professionals’ attitude in either condemning their wishes to get pregnant or encouraging termination. Particular conditions for which women should consult specialist care prior to or very early in pregnancy include:
• Diabetes—Ray et al (2001) showed that preconception care accompanied with good glycaemic control lowers the risk of fetal abnormalities in diabetic pregnancies. The recent UK Confidential Enquiry into Maternal and Child Health (CEMACH 2007) suggests dedicated preconception clinics (currently provided in 17% of UK units) in which expert help and advice are available for diabetic women is a most effective way of meeting the needs of these women.
• Epilepsy—Antiepileptic medications may be teratogenic, therefore adjusting the required dose under specialist care may help in reducing potential risks.
• Cardiac diseases—Collaboration with cardiologists is crucial.
• Oral anticoagulants—Changing to injectable medication under clinical specialist care may reduce the risk of teratogenicity.
• Hypothyroidism—The thyroid gland is important in human metabolism and the need for thyroid replacement therapy may increase in these women, thus timely intervention could reduce the risk of abnormal neurological development.
• Phenylketonuria—A diet reduced in phenylalanine before and during pregnancy can prevent damage to fetal brain development.
• Mental health—Minor and major forms of mental health disorders should be screened and supportive care offered.
• Acne—The treatment of women with isotretinoin should be stopped because of the risk of teratogenicity.
The healthy gamete
There is no clear demarcation between the health of the gametes immediately prior to conception and the developing embryo. In both instances cells are developing rapidly and are vulnerable to disruption. Even when pregnancies are planned, it is unlikely that a couple will consider the importance of those 100 days of gamete formation (explained by Foresight, an association for the promotion of preconception care—see below). The continuously produced sperm are also at risk of environmental insult. In the female fetus the primary oocytes have already undergone their first reduction division early in the first trimester and no further ova will be generated after the fifth month of gestation. In this arrested stage of development they are relatively resistant to mutagenic damage. Sensitivity increases just prior to ovulation and the mutation rate from radiation may rise sharply.
Following fertilisation, the zygote becomes resistant to genetic injury while undergoing cleavage, but after 16 days intense organogenesis begins. Sensitivity is high but so few cells are present that either the fetus will be affected and aborted spontaneously or not affected and be normal. This may account for a considerable proportion of unexplained pregnancy losses within the first 6 weeks.
General health care
The medical, obstetrical, social and family history of both the man and the woman is taken and known personal or familial health problems are discussed. A gynaecological examination of the woman and screening of blood and urine and, in some cases hair, stool and semen analysis, are carried out. Any infections should be treated, dietary problems discussed and possible work and lifestyle hazards considered.
A general risk assessment through questioning or using technology helps to identify potential problems and develop appropriate individualised care pathways sensitive to the needs of a mother and her baby. The main relevant issues that can be screened by making simple enquiries are summarised by Chapple (2007). Those, in addition to items addressing wider general health issues, are presented below.
Social history
The impact of maternal age on pregnancy outcome at both ends of the reproductive age is important. Teenagers are more likely to be anaemic, or at risk of having growth-restricted infants, preterm labour and higher infant mortality. Most teenage pregnancies are unplanned, therefore they rarely present for preconception care. Early pregnancy counselling could still be helpful. Pregnancies in later life (after 35) are also more likely to be at risk of obstetric complications (e.g. chromosomal abnormalities). However, for physically fit women the risks are lower than previously reported. Some pregnancy outcomes have been shown to be strongly related to the socioeconomic and health status of the mothers, particularly in this age group. These are hypertension, diabetes, placental abruption, preterm delivery, stillbirth and placenta praevia.
Socially disadvantaged women, asylum seekers and women at risk of mental health problems require integrated care from an early stage of pregnancy or ideally before pregnancy (CEMACH 2007). Providing preconception care is, of course, more challenging for such women due to a non-compliance behavioural pattern and reduced access to routine care. However, providing creative outreach services and/or opportunistic care targeting such vulnerable groups can have a huge impact on improving health and reducing maternal health inequalities.
Hair mineral analysis
Hair analysis for mineral content—which involves taking a sample of scalp hair and using equipment that can measure contaminants—is still regarded as fringe research by some practitioners, but studies confirm its usefulness. Both an excess of toxic minerals and a shortage of essential minerals may cause reproductive problems. Some toxins are eliminated from blood and stored in body tissues. Hair grows slowly and will show traces of whatever has passed into the follicle in the previous 6–8 weeks. Hair analysis can therefore be a useful addition to blood and urine tests to screen for minerals. The group Foresight have a fantastic website (Foresight 2008) and the founder of the group has written a small booklet outlining the programme (Barnes 2007). The information includes testing for the following minerals and gives advice depending on the findings:
• Essential minerals: calcium, magnesium, potassium, iron, chromium, cobalt, copper, manganese, nickel, selenium and zinc.
• Toxic minerals: aluminium, cadmium, mercury and lead. The last two are discussed below.
Either supplementation of essential minerals or removal of toxic minerals by methods such as chelation may be offered.
Nutrition and weight
Establishing a balanced diet and a healthy lifestyle prior to pregnancy increases the chance of a successful pregnancy outcome. Prepregnancy weight is positively related to infant birth weight. In developed countries it is rare to find overt malnutrition except in people with eating disorders such as anorexia nervosa.
Poor nutrition
It is not ethically acceptable to experiment on the effects of food restriction on the human fetus. However, retrospective studies during famine provide some information. The Dutch famine of 1944–45 showed that there was more early pregnancy perinatal mortality in undernourished women and that fertility can be reduced by sudden falls in energy intake (Barker 1992). Barker has spent 20 years studying the effects of the fetal environment on adult-onset diseases and has written many journal articles and books, including one aimed at educating parents on the importance of prenatal nutrition (Barker 2003). Perhaps, as a protective measure, nature ensures that women who are too thin or too fat have difficulty in achieving ovulation and fertilisation. There may be a difference in an acute energy deprivation in comparison to a chronic nutritional deprivation. Maternal metabolism adjusts to optimise nutrient availability for the growing fetus.
Obesity
Obesity is a growing problem in industrialised societies, its rate having doubled since the 1980s in the UK. According to UK obesity statistics, 32% of women are overweight and a further 21% are obese. Obesity is associated with increased risk of complications such as gestational diabetes and pre-eclampsia, thrombophlebitis, post-term pregnancy, caesarean delivery, macrosomia and instrumental delivery (Wolfe 1998). Obese women are prone to further development of obesity after pregnancy, particularly the central type of obesity (Soltani & Fraser 2000). This is the pathological type which leads to higher risk of metabolic disorders such as metabolic syndrome, diabetes and cardiovascular disease (Byrne & Wild 2005).
There is no clear guidance with regard to dieting during pregnancy, thus it is very important to adjust maternal diet and weight prior to conception. Prepregnancy weight influences pregnancy outcome. Being undernourished is associated with fetal abnormality and low birth weight, while being obese brings the risk of complications of pregnancy mentioned above.
A guide to ascertaining the optimum weight for a woman is the Quetelet index or body mass index. This is obtained by using the formula of weight (kg) divided by height squared (m 2). The following BMI range is used as a guide:
• Less than 20: underweight.
• 20–24.9: desirable weight.
• 25–29.9: overweight.
• 30 and over: obesity.
• 35 and over: severe obesity.
Specific nutrient abnormalities
Suboptimal dietary deficiencies are common, especially in areas of high unemployment and poverty or women with dietary restriction (vegans or vegetarians).
The importance of nutrition in male fertility has rarely been investigated. Protein, energy and possibly zinc deficiencies may be linked to reduced spermatogenesis (Wharton 1992). There is mounting evidence implicating specific dietary deficiencies affecting the process of organogenesis in the embryo, mainly related to folic acid and zinc.
Although the mechanism is not clear, studies have shown that supplementation with folate/folic acid around conception can prevent neural tube defects (NTD) in the fetus (Schorah & Smithells 1991). It is therefore advised that women planning a pregnancy should take 0.4 mg folic acid as a daily supplement from when they try to conceive until the 12th week in pregnancy (DOH 1993). Women are also encouraged to eat more folate-rich foods (e.g. green beans, peas and dark green leaf vegetables) and avoid overcooking them.
Maternal zinc status is also essential in fetal development. The degree to which maternal zinc deficiency can lead to teratogenic effects in humans is unclear but there is limited evidence that severe maternal zinc deficiency may lead to fetal abnormality (Soltan & Jenkins 1982).
Excessive intake of fat-soluble vitamins is harmful. An epidemiological study in Spain (Martinez-Frias & Salvador 1990) showed an increased risk of birth defects in babies of mothers who had taken high levels of vitamin A (6000–167 000 μg) during the first 2 months of pregnancy. Although its role in causing human abnormalities is not confirmed, in the UK it is advised that women who might become pregnant should avoid vitamin A supplements unless suggested by a doctor or antenatal clinic. Women who are pregnant or might become pregnant are also advised against eating liver or liver products because of its high vitamin A content (National Dairy Council 1994).
Drugs
Drugs may be teratogenic, reduce absorption of nutrients or interfere with normal growth and development. The placenta is not a complete barrier against all chemicals.
Many people are exposed to drugs used to treat medical conditions. These may be essential for treatment and difficult to withdraw or reduce. Sometimes they can be substituted by less toxic drugs or stopped altogether during pregnancy. Women of childbearing age should only take medicines under medical supervision and medical practitioners should be alert to the teratogenic side effects of drugs. People may purchase drugs for minor problems such as pain and indigestion without their doctor’s knowledge. The doctor may then prescribe drugs that exacerbate the effects of the over-the-counter drugs. The public should be informed about the danger of taking drugs in pregnancy.
Women are usually advised to discontinue the use of hormonal contraceptives at least 3 months prior to the time they wish to get pregnant. This allows the body to readjust its hormonal system and resume physiological menstrual cycles, as well as regulating the level of minerals and vitamins which may be affected by the contraceptive pill. Mineral and vitamin levels may also be affected by intrauterine devices, especially if they contain copper which can interfere with absorption of zinc and cause zinc deficiency.
Drugs may be taken for recreational reasons because of their mood-altering abilities. It is sometimes difficult to ascertain whether they are being taken and to help people to stop taking them. Such substances include alcohol, tobacco and caffeine as well as addictive drugs such as cocaine and its derivative crack, marijuana and heroin. With appropriate referral systems, preconception counselling would be most effective for women who habitually use drugs, as drug abuse is associated with malnutrition, alcohol abuse, smoking and a higher risk of sexually transmitted diseases.
Smoking and alcohol consumption
The dangers of smoking for general health and during pregnancy are well documented. Many harmful chemicals such as polycyclic aromatic hydrocarbons, carbon monoxide, cyanide, lead and cadmium are inhaled in cigarette smoke. The effects of smoking on reproduction are summarised below:
• Male and female infertility—Besides experiencing infertility, women who smoke often undergo an early menopause (Jick et al 1977). In men, smoking reduces testosterone levels, reduces the number and motility of sperm and increases the number of abnormal sperm (Evans et al 1981). Alcohol is a direct testicular toxin, causing atrophy of seminiferous tubules and an inhibiting effect on Leydig cells.
• Low birth weight—One of the most frequent adverse effects of smoking during pregnancy is reduced fetal growth, which is dose-dependent. Conter et al (1995) carried out a longitudinal study of 12 987 babies: 10 238 from non-smoking mothers, 2276 from mothers smoking 1–9 cigarettes/day and 473 from mothers smoking more than 9 cigarettes/day. The results confirmed the association of smoking during pregnancy with lower birth weight. However, the reduction in birth weight was overcome by 6 months of age and was not permanent.
• Increased perinatal mortality
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