Early Years Nutrition and Healthy Weight E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 298

Veröffentlichungsjahr: 2015

Beschreibung

Early Years Nutrition and Healthy Weight focuses on the early years of childhood as a key period in which eating and exercise habits are formed. Combining current evidence with practical advice, an international group of health specialists advise on the avoidance and management of childhood obesity. They look at key risk areas such as early sedentary behaviour, parental influences and underlying medical causes, and also investigate practical interventions including advice during pregnancy, parenting strategies, and prevention during pre-school and the early school years.

This practical handbook contains vital information and advice for all nutritionists and dietitians working with young children and families. It will also be a valuable text for health visitors, paediatricians and general practitioners, and students of nutrition and dietetics specialising in paediatric nutrition.

Key features:

• Only practitioner handbook dedicated to the early years of childhood as the key to ensuring healthy weight in later life
• Covers pregnancy through to pre-school and early school years interventions
• Also addresses the social and psychological issues that underpin nutritional problems
• International group of expert authors consider the issue across the developed world
• Case studies in each chapter illustrate the application of theory to practice

Leseprobe

CONTENTS

Cover

Title page

Copyright page

Editors

Contributors

Foreword

References

Acknowledgments

Chapter 1: Importance of good health and nutrition before and during pregnancy

Introduction

Importance of good maternal health before and during pregnancy

Link between maternal diet and foetal growth

Micronutrients most likely to be at risk in pregnancy

Iron

Vitamin D

Folic acid supplementation to prevent neural tube defects

Weight gain in pregnancy: what is optimal and how can this weight change be judged?

Why is excessive gestational weight gain a concern in pregnancy?

Pre-conception interventions

Current practice

Impact of pregnancy and breast feeding on energy requirements

Underweight and pregnancy outcome

How can the excessive GWG be challenged?

Conclusions

References

Chapter 2: Nutrition and health in the early years

Introduction

Milk feeds for infants

Complementary feeding

Children 1–4 years of age

Drinks

Developmental changes in pre-school-aged children

Common nutritional problems in pre-school-aged children

Impact of socio-economic status

Putting the evidence into practice

References

Further reading

Chapter 3: Defining and measuring childhood obesity

Introduction

Variations in growth and adiposity with age

How is adiposity measured in childhood?

Body composition measures

How is obesity defined?

What thresholds should be used?

What chart tools are available to assess overweight?

Putting the evidence into practice

References

Chapter 4: Early life risk factors for childhood obesity

Established early life risk factors for childhood obesity

Early life risk factors for obesity at age 7 years identified by ALSPAC study

Rapid early growth

Formula milk feeding in infancy

Television viewing

Lack of sleep/disrupted sleep

Early life risk factors for later obesity not studied in ALSPAC

Putting the evidence on early life risk factors for childhood obesity into practice

References

Chapter 5: Early physical activity and sedentary behaviours

Introduction

Physical activity, sedentary behaviour and health in the early years

Tracking of physical activity and sedentary behaviour

Recommendations on levels of physical activity

Recommendations on levels of screen-based entertainment

Recommendations on levels of sedentary behaviour

Summary of recommendations

Conclusion

Putting the evidence into practice

References

Chapter 6: Talking about weight with families

Introduction

What makes childhood obesity a sensitive issue?

Perceptions of child obesity and the challenge of identification

The impact of screening programmes

General principles of handling sensitive conversations

References

Chapter 7: Parenting strategies for healthy weight in childhood

Introduction

Influence of parents on family eating styles, food and physical activity habits and sedentary behaviours

Parent–child interaction

Parent engagement

References

Chapter 8: Pre-school prevention interventions

Introduction

Family approach

Availability and accessibility of food

Physical activity and sedentary behaviour

Obesity prevention and early years settings

References

Chapter 9: Contribution of food provision in primary schools to the prevention of childhood obesity

Introduction

The United States Department of Agriculture

School-feeding programmes are opportune places to address nutrition-related concerns

Lunches brought from home

Initiatives to improve the school environment

Initiatives to improve the family and community environment: Kids Eat Right

Community-based programmes

References

Chapter 10: Early clinical interventions and outcomes

Introduction

Clinical assessment and outcomes

Treatment strategies

Challenges in providing clinical services to obese children

Child protection issues and severe obesity

References

Index

End User License Agreement

List of Tables

Chapter 01

Table 1.1 United States Institute of Medicine guideline weights for maternal weight gain according to BMI.

Chapter 02

Table 2.1 Energy densities of breast milk and infant formula milk according to European regulations.

Table 2.2 Developmental stages of weaning.

Table 2.3 Food groups and recommended servings for infants on three meals per day.

Table 2.4 Pattern of feeding during weaning.

Table 2.5 Food groups and recommended servings for children 1–4 years.

Table 2.6 Portion size ranges for children aged 1–4 years.

Chapter 03

Table 3.1 Advantages and disadvantages of different methods of assessing body composition in childhood.

Table 3.2 BMI thresholds in use in UK and USA.

Table 3.3 BMI thresholds in use in UK and USA.

Chapter 04

Table 4.1 Well-established early life risk factors for childhood obesity in ALSPAC [5].

Chapter 05

Table 5.1 Association between physical activity and health outcomes.

Table 5.2 Association between screen time and health outcomes.

Table 5.3 Summary of existing physical activity guidelines/recommendations for the early years.

Table 5.4 Summary of existing screen-based entertainment guidelines for the early years.

Table 5.5 Summary of existing sedentary behaviour guidelines related to sitting time in the early years.

Chapter 06

Table 6.1 Phases involved in constructing weight feedback conversations that are responsive to parental sensitivities.

Chapter 08

Table 8.1 Healthy eating in toddlers.

Table 8.2 Promising childhood obesity prevention programmes in the child care setting.

Chapter 09

Table 9.1 School Meals Initiative (SMI) for healthy children guidelines.

Table 9.2 HUSSC Guidelines 2011–2012: food groups.

Table 9.3 HUSSC Guidelines 2011–2012: menu, food, and school health policies and practices.

Chapter 10

Table 10.1 Elements of a clinical history in obese children.

Table 10.2 Measures of outcome success in childhood obesity.

Table 10.3 Key elements of obesity treatment in young children.

Table 10.4 Challenges, and possible strategies, in managing childhood obesity in ‘real-life’ clinical settings.

List of Illustrations

Chapter 03

Figure 3.1 50th centile for BMI (UK 1990), genders compared.

Figure 3.2 50th centile for (a) triceps and (b) subscapular skinfolds.

Figure 3.3 BMI compared to WHO, UK 1990 and CDC references in (a) girls and (b) boys.

Figure 3.4 BMI lookup as provided on UK-WHO 2–18 years growth chart. Draw a vertical line from height centile on

X

-axis to meet a horizontal line drawn from the weight centile on the

Y

-axis. Where the two lines cross, read off BMI centile from the diagonal lines: 98th centile in this example.

Figure 3.5 BMI chart as provided on UK-WHO 2–18 years growth chart.

Chapter 07

Figure 7.1 Spheres of influence on child’s weight status.

Figure 7.2 Parent/child feeding interaction relationships.

Chapter 08

Figure 8.1 The eatwell plate.

Guide

Cover

Table of Contents

Begin Reading

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Editors

Dr Laura Stewart PhD, BSc, BA(HONS), RDLaura Stewart works for NHS Tayside in Scotland, UK. She is the Tayside Weight Management Pathway Manager, managing both adult and childhood obesity, while clinically specialising in childhood weight management. Laura graduated with a degree in Dietetics from Queen Margaret University, Edinburgh, in the early 1980s and has worked for the UK NHS since that time. She was a member of the Scottish Intercollegiate Guideline Network (SIGN) working groups on obesity for SIGN 69 (2003) and SIGN 115 (2010). She is a past chair of the British Dietetic Association’s interest group Dietitians in Obesity Management UK (DOM UK). In 2014, Laura was a member of an Expert Group on childhood obesity which was set up to advise the Scottish Government.Joyce Thompson MPH, BSc, RDJoyce Thompson is a registered dietitian and works for NHS Tayside in Scotland. She was appointed as the Dietetic Consultant in Public Health Nutrition in 2004, Scotland’s first Allied Health Profession consultant post. Joyce graduated with a degree in Dietetics from Queen Margaret University, Edinburgh, in 1982. She co-founded DOM UK and became its first chairperson. Joyce chaired the SIGN working group on obesity for SIGN 115 (2010).

Contributors

Foreword

Childhood obesity is among the most common of chronic diseases and potentially one of the most preventable. Recent data from the USA suggests that although approximately 15% of pre-school children were overweight before they completed kindergarten, or when they were approximately 5.6 years of age, incidence of obesity in this group accounted for almost half of obesity present in 14-year-old adolescents [1]. In addition, although increased birth weight occurred in 12% of infants in this cohort, adolescents with increased birth weight accounted for over one-third of obesity present in 14-year-olds. These observations emphasize that successful, early efforts to prevent obesity in pre-school children or to successfully treat young children who are overweight or obese may be one of the most cost-effective strategies to reduce childhood obesity.

Two important repeated US cross-sectional studies suggest that increased awareness and changes in the consumption of high caloric density foods may already have begun to reduce the prevalence of obesity in pre-school-aged children. The Pediatric Nutrition Surveillance System (PedNSS) is an annual state-based survey of low-income children, most of whom are enrolled in the Women, Infants, and Children (WIC) food supplementation program. Between 2008 and 2011, the prevalence of obesity among several million 2–4-year-old children enrolled in PedNSS decreased in 18 states by approximately 5% (range 2–11%) [2]. Additional data from approximately 900 2–5-year-olds studied in the National Health and Nutrition Examination Survey (NHANES) reported a decrease of approximately 40% between 2004 and 2012 [3]. However, if that report had included earlier data from NHANES, the decrease would have been less dramatic.

The mechanism that can account for the decrease in prevalence in the USA can be understood in terms of the modest caloric deficits necessary to prevent obesity in young children. For example, the caloric deficits necessary to return the mean body mass index (BMI) to its 1970s level by the year 2020 is approximately 30 kcal/day for 2–5-year-olds, 150 kcal/day for 6–11-year-olds, and 180 kcal/day for 12–19-year-olds [4]. The decreases in early childhood obesity in the USA coincide with a number of shifts in the food supply and the consumption of high caloric density foods. The Healthy Weight Commitment Foundation is a group of food companies that supply approximately 25% of the calories in the USA. In 2010, these companies announced an effort to reduce the calories they provided by 1.5 trillion calories by 2015. Early in 2014, the companies announced that they had reduced the caloric content of their foods by 6.4 trillion calories, or approximately 78 kcal/person [5]. In addition, calories consumed from two of the leading sources of calories in the diets of children also declined. Energy from sugar drinks, which include colas and 10% juices, decreased by 37 kcal/day among 2–5-year-old US children [6], and fast food consumption decreased by 72 kcal/day among 2–11-year-old children [7].

These observations emphasize the importance and timeliness of a textbook devoted to the problem of obesity in young children. It is particularly appropriate to include the prenatal period, insofar as pre-pregnant weight, and excessive weight gain, tobacco use, and diabetes during pregnancy are all associated with early childhood obesity. A focus on risk factors in early childhood, such as the consumption of sugar drinks, fast food, and inactivity, is critical, in view of the growing appreciation of the effect of early onset of overweight on subsequent obesity. Although parenting is the final common pathway for these behaviors and their modification, only limited information exists regarding the parenting practices that predispose to childhood obesity and even less information on how to modify those behaviors. Finally, efforts to change the environment in places where children spend time, such as schools and child care centers, offer exceptionally promising loci for interventions, especially policy or regulatory strategies that increase the availability of low caloric density foods, reduce access to sugar drinks, mandate physical activity and limit screen time.

Although the caloric gap that can be achieved through policy changes in schools and child care will effectively prevent obesity, it will not likely be of sufficient magnitude to reduce body weight in those children who have already developed obesity. More rigorous clinical interventions will be required for this group. The development of effective clinical strategies for weight reduction will be even more challenging than the implementation of school and child care policies because physicians are poorly trained in how to begin a nonjudgmental conversation with families about their child’s weight and in techniques to change behavior. In addition, a problem as prevalent as childhood obesity will require substantial changes in the care delivery system, with reliance on clinicians other than physicians. Changes in how care is delivered will also require additional adjustments on the part of physicians, who will need to learn how to work with other care providers. Finally, clinical interventions without changes in the environment will not likely sustain prevention or sustain weight loss after it occurs.

This text effectively addresses many of these areas and its authors are experts in the field. Our hope is that the lessons learned from its reading will inspire action and can be effectively implemented to reduce the prevalence and virulence of childhood obesity.

References

1 Cunningham SA, Kramer MR, Narayan KMV. Incidence of childhood obesity in the United States.

N Engl J Med

2014;

370

(5): 403–11.

2 May AL, Pan L, Sherry B, Blanck HM, Galuska D, Dalenius K, Polhamus B, Kettel-Khan L, Grummer-Strawn LM. Vital signs: obesity among low-income, preschool-aged children – United States, 2008–2011.

Morbidity and Mortality Weekly Report

August 6, 2013;

62

: 1–6.

3 Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011–2012.

JAMA

2014;

311

(8): 806–14.

4 Wang YC, Orleans CT, Gortmaker SL. Reaching the healthy people goals for reducing childhood obesity: closing the energy gap.

Am J Prev Med

2012;

42

(5): 437–44.

5 Robert Wood Johnson Foundation.

Major Food, Beverage Companies Remove 6.4 Trillion Calories from U.S. Marketplace

. January 9, 2014.

6 Kit BK, Fakhouri TH, Park S, Nielsen SJ, Ogden CL. Trends in sugar-sweetened beverage consumption among youth and adults in the United States: 1999–2010.

Am J Clin Nutr

2013;

98

(1): 180–8.

7 Powell LM, Nguyen BT, Han E. Energy intake from restaurants: demographics and socioeconomics, 2003–2008.

Am J Prev Med

2012;

43

(5): 498–504.

William H. Dietz MD, PhDDirector, Sumner M. Redstone Global Center on Prevention and Wellness,Milken Institute School of Public HealthGeorge Washington University,Washington, DC

Acknowledgments

The editors, Laura Stewart and Joyce Thompson, would like to offer grateful appreciation and thanks to David Stewart, Kirsten Cumming and Sue Smart for their help with editing this book.

Chapter 1Importance of good health and nutrition before and during pregnancy

Catherine R. Hankey

Human Nutrition, University of Glasgow, Glasgow, UK

Introduction

Pregnancy is a time of anticipation and excitement, especially for healthy mothers with no known health concerns for their foetus. It is increasingly evident that the lifestyle and health practices of mothers can impact markedly on their own health and that of their foetus.

Historically, pregnancy has been associated with ‘blooming maternal health’ and is probably the only period across the life course when positive encouragement for weight gain is given by many, at least in the developed world. Increasingly, given the worldwide epidemic of obesity, this positive response to sometimes excessive weight gain in pregnancy has been less widely accepted, but it does still have cross-cultural impact. Pregnancy can also offer a positive setting which may increase the willingness of the individual to consider improving their health. It has been envisaged as a ‘new start’, which has been associated with positive improvements in lifestyle. Research has examined whether pregnant women can be encouraged to become more physically active, to attempt smoking cessation and to minimise or avoid alcohol intake. Attempts have been made to alter women’s food choice during pregnancy towards eating more healthy foods such as fruit and vegetables, and away from foods rich in fat and sugar which have often been associated with negative health consequences including the development of gestational diabetes (GDM). Good maternal health both pre-conceptually and during pregnancy has long been recognised as valuable. Evidence is accruing that preparing for pregnancy could offer real health benefits to both maternal and infant health, particularly in the context of the current obesity epidemic. However, this opportunity appears only available to few; for example in the UK, only around 50% of all pregnancies are reported as planned and there were close to 800 000 live births in 2012 [1].

Importance of good maternal health before and during pregnancy

Good maternal health is crucial to reduce the chances of adverse outcomes such as GDM, miscarriage, pre-eclampisa, still birth, macrosomia and caesarean section for the mother, and abnormal birth weight and increased risk of obesity in infancy for the unborn child.

Abstinence from smoking and alcohol consumption together with regular physical activity has long been advocated to pregnant women, given the benefits this can bring for maternal and foetal health. Maternal nutritional status has been recognised as important before and during pregnancy, to maximise the chances of a healthy pregnancy and an optimal outcome for both mother and infant. Historically, dietary advice for optimal health in pregnancy has focussed on healthy eating with an emphasis on the maintenance of good health in terms of dietary intakes, and a sufficient intake of macro- and micro-nutrients [2]. Dietary advice advocated for all adults and appropriate to pregnant women to increase awareness and encourage them to eat well is illustrated in the UK’s visual representation ‘The Eatwell Plate’ [3] (see Chapter 8). This graphic representation, designed for use by all adults, appears to have achieved consensus as a valuable tool, and as well as due to its widespread use in UK National Health Service (NHS), it is advocated by various health charities. However, uncertainties remain as to the scientific evidence on which the tool’s graphic representation is based.

It has recently been highlighted that most pregnant women want to know the best foods to eat and what they should avoid. Current issues of concern include the possible dangers of eating liver, the need to avoid unprocessed cheese and too much tuna and oil-rich fish beyond two portions per week [4, 5].

According to National Institute of Health and Care Excellence (NICE), alcohol, for those in the first 12 weeks of pregnancy, should be avoided completely, and intakes throughout the remainder of pregnancy ought to be very limited, due to potential negative effects on foetal health [6]. Furthermore, as alcohol supplies energy of 7 kcal/g, it is considered as a concentrated source of energy, and hence even moderate consumption may increase energy intakes and encourage excessive prenatal weight gain.

Maternal caffeine intake has received considerable interest, given suggestions that raised intakes increase the likelihood of foetal growth restriction. In a large prospective observational study in two UK maternity units [7], retrospective caffeine intakes were determined and findings indicated that low caffeine intakes (up to 100 mg/day) are safe, but higher levels, in excess of 200 mg/day, increased the risk of miscarriage, premature birth and low birth–weight babies. Two hundred milligram of caffeine equates to around two cups daily of tea and/or coffee, though other rich sources such as caffeinated drinks should also be considered. Decaffeinated versions of these drinks may be of value.

Link between maternal diet and foetal growth

Dietary patterns in pregnancy have been studied using factor analyses or similar component analyses to investigate links between maternal diet and foetal growth, and dietary patterns in pregnancy and their associations with socioeconomic status (SES) and lifestyle. This is arguably a clear way to examine diet and health relationships, as the human diet contains a wide variety of nutrients and many may correlate with health outcomes. Danish researchers looked at associations between dietary patterns and foetal growth in over 40 000 pregnant women. Three major dietary patterns were observed: (1) a western diet rich in dairy fat and red and processed meats, (2) a healthy diet rich in fruit, vegetables, poultry and fish and (3) a mixture of both. The health conscious pattern was associated with a 24% lower occurrence of a small for gestational age (SGA) babies [8]. This pattern was evident when parity, maternal smoking, age, height, pre-pregnancy weight and fathers’ height were included as confounding factors.

Using the Avon Longitudinal Study of Parents and Children (ALSPAC) data [9], Northstone et al. examined dietary patterns in the third trimester of pregnancy. Associations were determined between social and demographic characteristics and habitual dietary intake when estimated using a food frequency questionnaire. Dietary patterns were categorised into four broad groups: (1) ‘processed diet’, full of high fat foods, (2) the ‘confectionary diet’, (3) the ‘vegetarian diet’ and (4) the ‘health conscious diet’ where the latter dietary pattern fulfilled the majority of dietary targets and was favoured by educated, older and non-white pregnant mothers.

In contrast, poorer diets were favoured by pregnant woman who smoked and were white, young and overweight.

Whilst ALSPAC data indicated the associations between dietary patterns and characteristics of the pregnant women, the Danish study illustrated a positive link between poorer dietary patterns and SGA babies, when the socio-economic and other factors were controlled. This epidemiological evidence favours specific macronutrients or micronutrients that may be underlying the association with SGA.

Micronutrients most likely to be at risk in pregnancy

The micronutrients most commonly at risk of shortfalls are iron, vitamin D and folic acid. A recent systematic review confirmed that in the UK and other developed countries, intakes of all these micronutrients are consistently reported to be below national recommendations [10]. The accuracy of these findings has been compromised by the limitations of dietary intake measurements, but a clear trend towards suboptimal intakes is evident. For these reasons, this chapter will deliberately focus on these key micronutrients.

Iron

Recent estimates, according to the Nutrition Impact Model Study, of the worldwide prevalence of anaemia in pregnant women is 38% (95% CI 33–43), that is 32 (28–36) million pregnant women globally [11]. Anaemia in pregnancy, diagnosed using World Health Organization (WHO) guidance [12], is defined as a haemoglobin concentration less than 11.0 g/l. Around 50% of anaemia is estimated to be as a result of iron deficiency, the world’s most commonly occurring nutritional disorder. Inadequate iron intakes are known to compromise maternal and foetal well-being, and intervention strategies to manage the situation should be implemented. This usually comes in the form of dietary advice, but more common is iron supplementation.

Dietary approaches to managing iron status

Advice given in antenatal clinics should be appropriate with respect to iron status. The UK Scientific Advisory Committee on Nutrition (SACN) has recently summarised its guidance on how to challenge a shortfall in iron status: ‘a healthy balanced diet’, which includes a variety of foods containing iron, will help people achieve adequate iron status [13]. Such an approach is more effective than consuming iron-rich foods at the same time as foods/drinks that enhance iron absorption (e.g. citrus fruit juice, red meat) whilst avoiding foods containing components that inhibit iron absorption (e.g. tea, coffee, milk).

Given the increasing concern that one of the major sources of dietary iron – red and processed meat products – has been linked to the development of colon cancer, the SACN report indicated that intakes of red and processed meat, which they considered high, ≥90 g/day should be reduced by at least 20% to a total intake of 70 g/day cooked weight. The committee considered that reducing red meat intakes by this magnitude would not compromise iron status in those of the adult population with low intakes but could beneficially affect colon cancer risk.

The risk of compromised iron status is increased in pregnancy, given its additional iron requirements. Iron requirements increase across pregnancy, reaching 30 mg/day during the final trimester. In order to help satisfy these increased needs, the proportion of iron which is absorbed in pregnant woman is increased from around 15% of all consumed to up to 45%. Education and counselling regarding diet may improve iron intake and enhance absorption but the degree of change achievable, especially in ‘hard to reach’ individuals, such as those living in deprivation, ethnic minorities, etc. remains in doubt.

How effective are iron supplements in pregnancy?

The effectiveness of iron supplements in pregnancy for those with anaemia has recently been evaluated in a systematic review and meta-analysis [14]. This review used international data to summarise the available evidence on the associations of maternal anaemia and prenatal iron use with maternal haematology and adverse pregnancy outcomes. Any relationships between exposure and response were examined such as between dose of iron, duration of use and haemoglobin concentration in the prenatal period, with pregnancy outcomes. Daily prenatal use of iron substantially improved prenatal mean haemoglobin concentrations. The authors concluded that given the worldwide prevalence of anaemia and iron deficiency, they considered it justified to expose an entire population (i.e. all pregnant women) to iron supplementation. As iron deficiency is a preventable disease for which cost-effective treatment is easy to administer, they felt justified in their conclusions. A Cochrane review [15] also concluded that prenatal daily or weekly iron supplementation was effective in reducing the risk of low birth–weight babies and in preventing maternal anaemia and iron deficiency. Iron absorption is physiologically regulated and relies on the natural mechanism regulating total body iron; therefore, it should protect against iron overload. Side effects, and hence poor compliance, can be relieved by administration of the iron supplements with food, although this may decrease absorption, particularly of ferrous preparations.

Iron supplementation to all ‘healthy’ pregnant women

In contrast to the views detailed earlier, it has been recommended that routine iron supplementation is unjustified in ‘healthy’ pregnant women [16]. Their argument is twofold. Firstly, the number of hazards associated with iron supplementation, not least that the preparation can be toxic, and oral iron supplements often have gastrointestinal side effects, which are unpleasant. Therefore exposing an entire population to excess iron is unjustified and should not take place without good reason. Secondly, the case for oral iron supplementation should ideally be guided by early or pre-pregnancy ferritin measurements. The view taken by NICE [6] and the British Committee for Standards in Haematology [17] is that iron status in pregnancy ought to be reviewed routinely, and all women should have a full blood count taken at the booking appointment (week 12 of pregnancy) and at 28 weeks [6]. This should facilitate selective iron supplementation early in pregnancy, although effective systems must be in place for rapid review of blood results and appropriate follow-up.

In the UK, pregnant women with a haemoglobin level less than 11 g/l up until 12 weeks or less than 10.5 g/l beyond 12 weeks should be offered a trial of therapeutic iron replacement. In non-anaemic women at increased risk of iron depletion, including those with previous anaemia, multiple pregnancy or consecutive pregnancies with less than a year’s interval between and vegetarians, a serum ferritin measurement (the best indicator of maternal iron stores) should be considered. If the ferritin level is less than 30 μg/l, then 65 mg elemental iron once a day should be offered [17].

Vitamin D

Inadequate vitamin D status is becoming increasingly common in pregnant women. Those with coloured skin, who live in cool climates where sunlight levels are limited and insufficient to allow vitamin D to be synthesised in the skin, are especially vulnerable. Covering of almost all skin, sometimes leaving only the eyes visible as evident in devout religious women leads to poor vitamin D status, especially in a temperate climate such as the UK. The occurrence of infantile rickets is increasing and highlights the need for provision of vitamin D supplements to all those at risk of poor vitamin D status in pregnancy. To meet this goal, 10 μg daily supplementation of vitamin D is advocated throughout pregnancy [6, 18] with a need for clinicians to be especially vigilant towards the vitamin D status of women from black and ethnic minorities, the socially excluded, those with limited exposure to sunlight and the obese (pre-pregnancy body mass index (BMI) >30 kg/m2). The latter group is considered to be susceptible to vitamin D deficiency due to the sequestration of vitamin D into adipose tissue, rather than liver sites, where it then becomes unavailable [19]. Despite the additional requirements of pregnancy, there is insufficient evidence to advocate increasing the daily 10 μg vitamin D supplement level [18].

Folic acid supplementation to prevent neural tube defects

In 1991, folic acid supplementation among women planning a pregnancy was shown to prevent a proportion of neural tube defects (NTD) [20] and the evidence was overwhelming; national authorities such as the health departments for England, Wales and Scotland each have a consensus recommendation that all women planning a pregnancy should increase their intake of folic acid. The recommended folic acid intake is about double the current estimated dietary intake of 0.2 mg/day [21], though the mechanism of action is unclear.

As with vitamin D, there have been suggestions that higher levels of folate supplements are required for obese pregnant mother. These larger supplemental doses are required for a number of reasons, for example a higher risk of NTD in the obese; odds ratios for an NTD-affected pregnancy are 1.22 (95% CI 0.99–1.49), 1.70 (95% CI 1.34–2.15) and 3.11 (95% CI 1.75–5.46) for women defined as overweight, obese and severely obese respectively [22]. Folate status is shown to be lower in obese adults than in healthy normal weight adults probably due to a poor quality of diet , and it has been shown that a 0.2 μg dosage of folic acid has a lower impact reflected in lower plasma concentrations in obese adults than in healthy normal weight adult. However, a rate of supplementation guided by BMI may be justified by cogent research findings. Nevertheless, despite guidance by leading expert committees in the fields of obstetrics and gynaecology [23], the folic acid dosage for the obese remains at 0.2 μg/day rather than at 5 μg/day, as advocated by this guideline.

From a public health perspective, NTD affects only a minority of people at risk, hence, there is a dilemma over the widespread use of folic acid supplementation in flour and other food stuff. USA data report NTD incidence at about 3.5 cases per 10 000 births, a fall from 5 cases prior to the widespread use of prenatal folic acid supplementation. However, given the need for folic acid to be ideally consumed pre-conceptually, and at least up until the first 12 weeks of pregnancy, potentially many women do not comply with supplements. One approach to resolve this issue would be mandatory fortification of flour with folic acid, which currently occurs in over 70 countries worldwide but not in the UK.

Factors associated with poor uptake of folic acid supplements are perhaps predictable and include educating those individuals. An initiative in the north of the Netherlands resulted in 51% women using folic acid supplements appropriately [24]. The socio-demographic and lifestyle factors associated with non-compliance with pre-conceptual use of folic acid included non-western ethnicity, and not having a partner. Fortification of staple foods with folic acid would provide a more effective means of ensuring an adequate intake, especially for those groups of women who are unlikely to plan their pregnancies or to receive and respond to health promotion messages.

The SACN committee [25] believes that sufficient evidence exists to proceed with fortification of flour with folic acid, though the issue still remains under consideration. This is despite some apparent associations between excess folic acid intake and the incidence of colon cancer, although the epidemiological data to date remain inconclusive. However, as with any large public health initiative, consideration of other population groups is required, before implementation. In this case, in order to avoid exposing groups of the population to higher than recommended doses of folic acid, voluntary supplementation of foods with folic acid should be prevented, prior to any country wide fortification.

Weight gain in pregnancy: what is optimal and how can this weight change be judged?

Given the widespread increase in the prevalence of overweight and obesity, with greater numbers of women affected than men, specific guidelines for optimal weight gain throughout pregnancy are justified. UK data report a doubling of maternal obesity from 7.6 to 15.6% between 1989 and 2007 [26], an observation which has now been replicated across the developed world. The United States (US) Institute of Medicine