Chapter 2: Why is Maternal and Infant Nutrition Important?
Food, Nutrition and Health
2.1 A typical diet in Scotland is one which is too low in fruit and vegetables, fish and complex carbohydrates including dietary fibre, and too high in fat, sugar 1 and salt. 2 This type of diet is more likely to contain inadequate levels of essential nutrients and to be energy dense. Poor diet has been linked to the development of cardiovascular disease, cancer, type 2 diabetes, overweight and obesity 3 - all of which are high in Scotland. Individuals coming to Scotland from other countries and adopting Scottish dietary patterns also tend to have poorer health outcomes, with the incidence of type 2 diabetes in particular high amongst some ethnic groups 4.
2.2 Overweight and obesity ( 1) are rising across both developed and developing countries. 5 In 2009 26.8% of men and 26.4% of women in Scotland were obese, 66.3% of men and 58.4% of women were overweight (including obese). For children the corresponding rates were 14.4% and 28.2% 6. Overweight occurs when energy intake from food and drink consumption, including alcohol, is greater than the energy requirements of the body's metabolism over a prolonged period, resulting in the accumulation of excess body fat. People who are overweight or obese are more at increased risk of a range of diseases, in particular cardiovascular disease, cancer, type 2 diabetes, osteoarthritis and gallstones. 5
Maternal Nutrition and Foetal Growth and Development
2.3 Women are advised to follow general healthy eating advice before, during and after pregnancy. Healthy eating advice for women during these periods of time is provided on the Food Standards Agency eatwell website ( www.eatwell.gov.uk) and is summarised in Appendix 3.
2.4 Survey data suggest that, taken as a whole, women of reproductive age including those who have adequate intakes of energy, have poor dietary intakes of some key nutrients including iron, calcium, folate, vitamin D and have low iron and vitamin D status. 7 As chapter 3 highlights, there is very little data on the dietary intake and nutritional status of pregnant women.
2.5 During pregnancy there is increased demand for several key nutrients such as vitamin D, folate, iron and calcium. 8, 9 This increased demand for iron and calcium for example can be met by consumption of foods rich in these nutrients and by normal physiological adaptations which increase absorption. Provided maternal stores of iron and calcium are adequate at the onset of pregnancy, there is no recommendation to increase intake of these nutrients over and above the RNI for non pregnant women. ( 2) However, for vitamin D and folate the increased amount required cannot be met from food sources alone, therefore, it is recommended that all pregnant women take a daily supplement of each, in addition to increasing their dietary intake. Women are advised to take a daily supplement containing ten micrograms of vitamin D during pregnancy and while breastfeeding. 8, 9 The main source of vitamin D is usually through the action of sunlight exposure to the skin. However populations living in more northern latitudes, including Scotland, receive lower levels of vitamin D through this process and therefore have to enhance their intake through a combination of diet and supplements. 8, 9 Before conception and until the 12 th week of pregnancy, women are advised to take a folic acid supplement of 400 micrograms per day to reduce the risk of having an infant with a neural tube defect. In addition, women are advised to eat foods rich in folate and folic acid to increase their nutrient intake to 300 micrograms per day for the duration of their pregnancy. 9-11 Women with a BMI of >30 are advised to take a higher dose of folic acid (5mg). 81
2.6 It is vital that the mother's diet contains adequate nutrients and energy at each stage to allow proper foetal growth and development, as well as providing all the nutrients the mother requires for maintaining her own health. If supply of nutrients and energy is limited, especially at critical stages, growth and development of the foetus may be impaired, for example organs such as the brain may not form properly or their functioning ability may be reduced, and the infant may be born small for gestational age ( 3). 12, 13 Poor foetal growth and development can lead to differences in body composition and metabolic and physiological function, which may lead to cognitive impairment and influence the development of chronic disease in later life. 14 Animal studies show that such changes often take place in the periconceptional period or early in pregnancy. This is likely to have implications for human health given that a high proportion of pregnancies are unplanned and these changes may consequently have occurred before a woman knows she is pregnant. 12 This highlights the importance of a good diet and appropriate nutritional supplementation before pregnancy as well as during pregnancy. Women who chose to follow a vegetarian or vegan diet, or exclude certain foods from their diet for cultural reasons may require specific advice from health professionals to avoid deficiencies of key nutrients.
2.7 Nutrition during pregnancy is thought to provide the developing infant with an insight into the level of nutrition they will receive when they are born. Problems are thought to occur when the postnatal diet differs drastically from the diet received during pregnancy, therefore, an infant receiving poor levels of nutrition during pregnancy going on to receive a high calorie diet following birth would be at greater risk of developing disease in later life. 13
2.8 Foetal growth is affected by a number of other factors including genetics, physiological and social influences such as deprivation, smoking, drug and alcohol use as well as diet. 15
2.9 Whilst the precise mechanisms of how maternal dietary intake and nutritional status, before and during pregnancy, influences foetal development are not fully understood, the impact of birth weight on long term adult health is well established. 16
Birth Weight and Health
2.10 A mother's own birth weight, her pre-pregnancy weight and weight gained during pregnancy all influence the birth weight of her infant. 15 Mothers who were themselves born with a low birth weight, are twice as likely to have an infant with a low birth weight. 15 Low birth weight ( 4) and poor weight gain in infancy are linked to the development of chronic conditions such as cardiovascular disease, hypertension, insulin resistance, type 2 diabetes, dislipidaemia (altered blood fat levels) and obesity. 16, 17 Mean birth weight varies across ethnic populations and results from the UK Millennium Cohort study show that Indian, Pakistani and Bangladeshi infants are 2.5 times more likely to be born with a low birth weight than White infants. It is suggested that these differences between populations may be associated with socioeconomic factors although these mechanisms are not fully understood. 18
2.11 Evidence suggests that women born with low birth weight are at an increased risk of developing gestational diabetes if they become pregnant in the future. This risk is further increased if they become obese in adult life. 19 Both gestational diabetes and obesity may lead to pregnancies resulting in infants with increased birth weight.
2.12 Adolescent mothers are more likely to have an infant with a low birth weight and other poorer outcomes than adult mothers. 20 Pregnancy places additional physiological demands on adolescent mothers due to the fact that they are still growing themselves, therefore, they may be at higher risk of nutritional deficiencies.
Impact of Maternal Obesity on Health
2.13 Maternal obesity, defined as a BMI = 30 kg/m 2 at the first booking appointment, poses a significant risk to the health of the mother and infant. Obese women have an increased risk of developing type 2 diabetes, impaired glucose tolerance and gestational diabetes during pregnancy. 15 Infants born to mothers with gestational diabetes are more likely to have a higher overall fat mass, a higher percent body fat and are at greater risk of obesity as they progress through childhood, than those born to mothers with normal glucose tolerance. 15 Obese women also have higher rates of induction of labour, caesarean section and post-partum haemorrhage. Even where the obese mother's glucose tolerance is normal, obesity during pregnancy still increases the level of fat in the infant and predisposes towards bigger, heavier infants. In addition, maternal obesity increases the risk of stillbirth, congenital abnormalities, premature birth and neonatal death. 21, 15 Given the rise in overweight and obesity in the general population and in women of childbearing age, the number of women likely to be entering their first pregnancy, and subsequent pregnancies, already overweight or obese is of concern. The Centre for Maternal and Child Enquiries ( CMACE) have recently published information on obesity in pregnancy: http://www.rcog.org.uk/news/cmace-release-cmace-publishes-information-obesity-pregnancy
Impact of Maternal Obesity on Breastfeeding
2.14 Studies suggest obese women are less likely to initiate breastfeeding and breastfeed for a shorter duration. 22 The reasons are multifactoral but may be physiological, due to high progesterone levels which interferes with milk production, or psychological, due to greater dissatisfaction with body image in obese women. It is important that women identified as overweight or obese have early access to additional information and support and that health professionals are aware that such women may require increased support.
Infant Feeding and Health
2.15 During the first year of life there is a period of rapid growth, particularly with regard to brain development, therefore it is essential that the infant's diet provides an adequate supply of nutrients and energy. 13, 15, 23 The decision of how to feed an infant falls ultimately to the parent, in most cases to the mother, however, it is important that they are given information on the health benefits of breastfeeding and the risks associated with formula feeding to enable them to make a fully informed decision. During pregnancy parents receive a huge amount of information and it is important that this is relevant and not overwhelming. Information on infant feeding has to compete with information on a host of other issues, much of which may seem more pertinent prior to birth, however infant feeding should be discussed with all women as early as possible and be tailored to meet individual need.
The Importance of Breastfeeding
2.16 Breastfeeding is the natural way to feed infants. Breast milk provides a complete source of nutrition for first six months of life and contains a range of immunological substances that cannot be manufactured. 25
2.17 Breast milk contains a wide range of bioactive substances including transfer factors such as lactoferrin, enzymes, hormones, immunoglobulin's, leucocytes and anti-inflammatory molecules, all of which support the development of the digestive and immune systems of the growing infant. None of these bioactive substances can be replicated; therefore, none are present in infant formula.
2.18 The Scottish Government has adopted as policy World Health Organisation guidance recommending exclusive breastfeeding for the first six months of an infant's life. 24 It is recommended breastfeeding should continue beyond six months, alongside the introduction of appropriate solid foods, for up to two years of age or as long as the mother chooses. There is a large and robust body of evidence demonstrating the short and long term health benefits of breastfeeding for both mothers and infants. Infants who are breastfed are at reduced risk of ear, respiratory, gastro-intestinal and urinary tract infections, allergic disease (eczema, asthma and wheezing), type 1 diabetes, and are less likely to be overweight later in childhood. 26, 27 Furthermore, infants who are breast fed are less at risk of childhood leukaemia and sudden unexplained infant death, and there may also be an association with improved cognitive development. 25, 27 For several of these conditions the longer an infant is breastfed the greater the protection gained or the more positive the impact on long-term health. Pre-term babies that are breastfed are likely to have better eyesight and brain development than those who are not and have a reduced risk of necrotising enterocolitis. 25
2.19 Women who have breast fed are at lower risk of breast and ovarian cancer, hip fracture later in life as a result of osteoporosis and there is some evidence to suggest they are more likely to return to their pre-pregnancy weight. 25, 26, 28
2.20 The physiology of lactation is based on the production and action of hormones, prolactin and oxytocin. These hormones are known to have a powerful effect on mothers' sense of wellbeing which contributes to the bonding process between mother and infant, therefore the benefits of breastfeeding go beyond the nutritional value of breast milk. The process of attachment, where the infant and parent establish and develop a relationship, " helps the infant to develop the capacity to control feelings, deal with stress, be adaptable and to form future relationships." 29 Infants with poor attachment are at greater risk of problems including emotional development, behavioural difficulties, low self-esteem and schooling difficulties later in childhood. In addition, infants with poor attachment are more likely to suffer from anxiety and depression in adulthood.
2.21 Women who know about the health benefits of breastfeeding are more likely to start breastfeeding, 30 therefore it is essential that in the antenatal period the health benefits of breastfeeding are discussed and explained to all women.
2.22 For a more comprehensive analysis of the health benefits of breastfeeding see, for example:
- Ip S, Chung M, Raman G et al. Breastfeeding and maternal and infant health outcomes in developed countries. Evidence Report/Technology Assessment No. 153. Agency for Healthcare Research and Quality, Rockville MD 2007.
- Horta B, Bahl R, Martines JC et al. Evidence on the long term effects of breastfeeding: systematic review and meta-analyses. World Health Organisation, Geneva 2007.
- World Cancer Research Fund. Food, nutrition, physical activity and the prevention of cancer: a global perspective. AICR, Washington DC, 2007
Initiation and Duration of Breastfeeding
2.23 Despite the significant health benefits of breastfeeding for both mothers and infants, breastfeeding rates in Scotland, the rest of the UK and parts of Europe, are low. 32Chapter 3 provides more detail on breastfeeding rates in Scotland.
2.24 It is important to have an understanding of the factors which influence a mother's infant feeding decision in order to develop effective strategies to encourage more women to breastfeed. These factors range from the attitudes towards breastfeeding of those closest to a mother such as her partner or mother/mother-in-law, whether she herself was breastfed as an infant, through the information and support received from health professionals, to the level of support she receives in her wider community. The factors are varied and complex and are summarised in Table 1. 33
2.25 Categorising the influences in this way highlights that whilst the health service has a significant role in encouraging and supporting mothers to breastfeed, many other organisations have a role to play in creating a supportive environment for breastfeeding mothers, as well as in changing broader societal attitudes so that breastfeeding is accepted as the 'cultural norm'.
Table 1: Influences on Initiation and Duration of Breastfeeding
Mother, child, family
- Age, parity, physical and psychological health of the mother
- Breastfeeding experience of the mother herself and with previous children
- Education, employment, social class, ethnicity, area of residence
- Knowledge, attitudes, confidence in the ability to breastfeed
- Marital status, family size, support from partner and family
- Lifestyles (smoking, alcohol, drugs, diet, physical activity)
- Birth weight, gestational age, mode of delivery, health of the newborn
- Access to role models who have had positive breastfeeding experiences
- Access to antenatal care and quality of care
- Quality of assistance during delivery and in the first few days
- Access to postnatal maternal and child healthcare and quality of care
- Type and quality of professional support for lactation management
- Access to peer counselling and mother-to-mother support
Public health policies
- Level of priority and financial support given to breastfeeding
- Official policies, recommendations and plans
- Breastfeeding monitoring and surveillance systems
- Quality of pre and in-service training of health workers
- Financial support for voluntary mother-to-mother support activities
- Communication for behaviour and social change and use of different media for breastfeeding advocacy
Social policies and culture
- Legislation on and enforcement of the International Code
- Legislation on maternity protection and its enforcement
- Representation of infant feeding and mothering in the media
- Obstacles and barriers to breastfeeding in public
- Prevalence and activities of mother-to-mother support groups
- Level of community awareness and knowledge
Infant Feeding and Growth
2.26 It is well established that breast fed infants can have a slower rate of growth than formula fed infants due to the difference in composition between breast and formula milk. The composition of breast milk changes between and during each feed in response to the infant's nutritional and developmental needs. From a physiological perspective, frequent feeding in the early days and weeks is important to establish maximum milk production. Breast fed infants are able to control the amount of milk they consume therefore they may learn to self-regulate their energy intake better than formula fed infants.
2.27 It is suggested that the difference in protein intake between breast and formula fed infants may contribute to later adiposity. The higher protein intake in formula fed infants is thought to programme later obesity through stimulation of insulin release and programming of higher long-term insulin concentrations. 34 Emerging evidence strongly suggests the first few postnatal weeks are a critical window for programming long-term health. Studies suggest that rapid weight gain in infancy is strongly associated with later risk of obesity. 15 Conversely, there is evidence to suggest that poor weight gain and under nutrition in infancy are associated with permanent stunting and cognitive impairment which leads to poorer outcomes in adulthood, such as fewer years of attained education, and lower adult productivity and earning capacity. 35
2.28 The new WHO Growth Charts were introduced in Scotland for all infants born on or after 1 st January 2010. 36 The Growth Charts were developed following a study of optimum growth in children undertaken in a selection of countries across the world. The study showed that the growth patterns in breastfed infants were similar and recommended that one growth chart which reflects optimum growth - that of breastfed infants - should be adopted for use across the world. On previous charts infants who were breastfed appeared to grow slowly which was commonly thought by health professionals to cause anxiety among mothers, who took this to mean that their infant was receiving insufficient breast milk.
2.29 Although evidence shows that breastfeeding is undoubtedly the healthiest way to feed an infant, there are many mothers who for a variety of physical, social or psychological reasons choose to feed their infant with infant formula. Most women are physically able to produce enough breast milk for their infant, as long as they receive appropriate advice and care 37.
2.30 It is essential that a mother is not judged or discriminated against for choosing to formula feed her infant; she should receive the same level of support as a breastfeeding mother.
2.31 Infant formula is manufactured using modified cows' milk and does not contain any of the protective antimicrobial or bioactive substances described previously. Powdered infant formula is not a sterile product and can therefore be a growth medium for harmful bacteria. It is essential that parents who choose to formula feed are shown how to prepare and use infant formula safely to minimise the risk of the infant becoming ill. Current advice from the Food Standards Agency recommends preparing one feed at a time, using boiled tap water that has been allowed to cool for no more than 30 minutes and adding water to the bottle first before powdered infant formula. 38
2.32 Clearly, mothers who choose not to breastfeed, and their infants, do not receive any of the health benefits of breastfeeding. It is not only the absence of breast milk that poses a risk to future health; giving infant formula in itself is associated with specific risks to infant health, for example, contamination of Enterobacter sakazakii( 5) during manufacture and preparation of powdered infant formula 39 or inappropriate reconstitution of powdered formula during preparation.
2.33 The Infant Formula and Follow-on Formula (Scotland) Regulations 2007 regulate minimum and maximum nutrient concentrations and food ingredients that can be used in the manufacture of infant formula. 40 There are two main types of infant formula - whey and casein based formula. It is recommended that whey based formula is used throughout the first year of life. There is no sound medical or nutritional reason to advise changing brand of infant formula or from whey to casein based infant formula. 33
2.34 Follow-on formula is manufactured for infants from the age of six months, however for most infants it has no advantage over standard infant formula and is therefore not recommended. 41 There is evidence that some mothers, particularly those in lower socio-economic groups, are giving their infants follow-on formula before the age of six months 30, posing additional risk to an infant's immature digestive system.
2.35 The WHO Code on the marketing of breast milk substitutes (which includes infant formula, other milk products, foods and beverages used as a partial or total replacement for breast milk, feeding bottles and teats) was launched in 1981 to protect all infants from inappropriate marketing of infant formula. 42 The Code does not prohibit the sale of breast milk substitutes but regulates their marketing to the public, limits the provision of product information to health professionals to a scientific and factual basis only and prohibits the promotion of products in all healthcare facilities. Promotional items such as pens, diary covers, calendars and weight conversion charts, for example, from infant formula manufacturers should not be accepted or used within any health service premises in Scotland. Sponsorship from infant formula manufacturers in the form of grants for attendance at study days or equipment or other materials should not be accepted by any part of the NHS in Scotland.
2.36 The Scottish Government is fully committed to the principles underpinning the WHO Code and expects all partner organisations, e.g. NHS, local authorities and the third sector, involved in improving infant feeding practices in Scotland to comply fully with it.
Introduction of Complementary Foods and Early Eating Habits
2.37 The introduction of complementary foods is commonly referred to as 'weaning' and means the gradual introduction of solid foods to an infant's diet alongside usual milk feeds (breast or formula).
2.38 Scottish Government policy, based on WHO guidance, is to recommend the introduction of solid foods at around the age of six months for all infants. 43 Breast 44 or infant formula milk provides all the nutrients most infants need for the first six months. At around six months and beyond infants' requirements for nutrients, particularly iron, cannot be met by breast or infant formula milk alone. Most infants are developmentally ready for complementary foods at around six months - this means they can sit with minimal support, hold their head up and can pick up food and put it in their mouth.
2.39 This allows parents to offer a variety of soft finger foods, and mashed family foods can be provided instead of smooth purees. This approach, often referred to as 'baby-led weaning' can have a positive effect, with the child being willing to try a wider range of healthy foods throughout early life.
2.40 Currently, the majority of infants in Scotland are introduced to complementary foods before six months 30, despite the fact that introducing complementary foods too early has been shown in the literature to pose risks to infant health. Before the age of four months an infant's bowel is immature therefore they are not able to digest and absorb food normally. There is evidence of increased risk of eczema if complementary foods are given before four months 45 and evidence of increased risk of type 1 diabetes if foods containing gluten are given before the age of three months. 46 Infants who receive complementary foods too early are more likely to suffer from respiratory and gastrointestinal illness compared to those given complementary foods at a later stage. There is also evidence, from the Millennium Cohort Study, to suggest that infants who receive complementary foods early are more likely to be overweight later in childhood. 47
2.41 A few studies have recently been published that are not fully consistent with the recommendations on age of introduction of complementary foods at around six months. 45, 48, 49 Any change to Scottish Government policy on exclusive breastfeeding and the age of complementary foods would be based on revised advice from SACN (Scientific Advisory Committee on Nutrition) following their review of more recent evidence. Current SACN advice on the introduction of solids continues to be at around six months for all infants.
2.42 The main influences on the timing of introduction of complementary foods are socio-economic status, maternal age, educational attainment and prior feeding experiences. 30 Mothers who introduce complementary foods early are more likely to base their decision on advice from family or friends, while mothers who introduce complementary foods later are more likely to base their decision on advice from a professional. 30 Furthermore, many mothers decide to introduce complementary foods before the recommended age based on the perception that their infant is hungry or not satisfied with milk feeds. 30
2.43 The type of foods and drinks given to infants is important for later health and establishing longer term eating habits. The types of foods and drinks given will also influence dental health therefore it is important to avoid foods and drinks containing sugar. Infants and young children have immature kidney function and so should not be given foods high in salt. Suitable first foods include fruits, vegetables and baby rice. It is recommended that the amount and variety of foods are gradually increased from around six months so that by the age of 12 months, food rather than milk is the main part of an infant's diet. After six months an infant's stores of iron become low therefore it is important that foods rich in iron are included regularly in the infant's diet to prevent anaemia. Foods rich in iron include red meat, eggs, pulses (peas, beans and lentils) and dark green leafy vegetables. In addition, it is recommended that foods rich in vitamin C are served at mealtimes in order to enhance the absorption of iron.
2.44 Parents are advised to use home prepared foods (without salt or sugar added) rather than commercially made baby foods so that the infant becomes accustomed to eating family foods.
2.45 Further detailed information for parents on complementary feeding can be found in NHS Health Scotland's publication 'Fun First Foods'. http://www.healthscotland.com/uploads/documents/12161-FunFirstFoods_English_2010.pdf
2.46 Early exposure to a variety of tastes and textures is important in the long term development of children's food preferences. Eating patterns and food preferences established in early childhood are likely to be carried on into later life. Findings from the Southampton Women's Study 50 showed that the quality of an infant's diet at six and 12 months is determined by the quality of the mother's diet, independent of other factors including educational attainment and smoking status. Interventions to improve the diet of mothers should be developed as this will have a direct impact on the diet of infants.
2.47 The timing of when lumpy food is introduced into an infant's diet has been found to have a significant effect on whether infants become fussy eaters as toddlers. Infants introduced to lumps late (from ten months of age) were more likely to exhibit difficult feeding behaviour by 15 months, for example they were more likely to be choosy and to have definite likes and dislikes, than infants introduced to lumps between six and nine months. 51 A follow up study of the same infants found that those introduced to lumps from ten months ate less of the foods in each of the main food groups and had significantly more feeding problems at seven years, than those introduced to lumps between six and nine months. Furthermore, infants who were introduced to lumps from ten months consumed fewer types of fruits and vegetables at the age of seven compared to those given lumps earlier. 52
2.48 The diet and nutritional status of the mother before conception and during pregnancy, the feeding received in the first few months of life, the process of weaning onto solid foods, and the diet and nutritional status of the growing infant all contribute significantly to the long term health of the population. 13, 15, 53 Poor nutrition during these critical developmental stages can lead to impaired cognitive, physical and economic capacity that cannot subsequently be restored. Maternal obesity increases the risk of complications for both the mother and the infant during pregnancy and birth, and influences long term health. A poor diet during pregnancy and early life has been linked to a range of conditions in adulthood including cardiovascular disease, insulin resistance, type 2 diabetes and obesity.