Establishing a healthy growth trajectory from birth: The Baby Milk Trial

Lead Research Organisation: MRC Centre Cambridge
Department Name: UNLISTED

Abstract

The prevalence of childhood obesity has increased rapidly over the past two decades. Excess weight in childhood tracks into adult life and causes problems both in the short term and in the long term. National surveys show that more than one in five children are already overweight (13%) or obese (10%) when they start school. Hence any efforts to prevent obesity must start early. The Foresight Report and the Healthy Weight Healthy Lives strategy have highlighted the importance of preventing childhood obesity by focussing on the early years. However, to date there is little evidence on which to develop effective preventive strategies. Infancy is a period of rapid growth and weight gain and obesity prevention during this period may be effective. Nutrition and growth during infancy may also have long term effects by altering eating behaviours and risks of obesity and obesity-related disorders in later life.

UK Infant Feeding Surveys show that at birth one in three (35%) of babies receive formula-milk and this number increases to almost all babies (92%) at 6 months of age. Hence, in addition to promoting breastfeeding, it important to optimise the growth of formula-milk fed babies. Our previous research shows that parents who give their babies formula-milk as part of their everyday diet need more information and support. Researchers at the Centre for Diet and Activity Research (CEDAR) and MRC Epidemiology Unit in Cambridge have been working with mothers and healthcare professionals to develop a feeding programme which aims to avoid excess weight gain in formula-milk fed babies. The programme we have developed aims to support parents who feed their babies formula-milk to achieve a healthy pattern of growth and weight gain.

The infant feeding programme will be tested in a randomised controlled trial involving 700 mothers and their babies. Half the mothers will be given advice and support to follow the new feeding programme. The other half will be given routine advice about formula-milk feeding and weaning. The growth of babies in the two groups will be compared. This comparison is important to test whether our new feeding programme is effective in preventing excess weight gain and subsequent obesity.

The results of the study will help to inform infant feeding guidelines and will also help us understand the links between infant feeding, behaviour, appetite and growth.

Technical Summary

Data from the National Child Measurement Programme show that in England, by the time children start school, 13% are overweight and a further 10% are obese. Infancy is a period of rapid growth, developmental plasticity and habit formation; hence could be a critical period when obesity prevention may be most effective.

Current UK formula-milk feeding instructions are based on 1985 World Health Organisation (WHO) recommendations. In 2004, based on new data on energy expenditure in infants, the WHO suggested that 1985 recommendations overestimated infant energy requirements. The WHO 2004 recommendations have been endorsed by the UK Scientific Committee for Nutrition in their Draft Energy Report. Since the instructions on the formula-milk tins are based on the old 1985 recommendations for energy requirements, this may contribute to excess weight gain in formula-milk fed infants.

We aim to evaluate the cost-effectiveness and acceptability of a theory-based behavioural intervention to avoid excess formula-milk intake and to prevent rapid weight gain during infancy. Guided by the MRC framework for complex interventions, our multi-disciplinary group have used an iterative process to optimise the proposed intervention and its evaluation.

We will recruit 700 mothers who introduce formula-milk feeds within six weeks of their baby's birth into a randomised controlled trial. The intervention group will receive the behavioural intervention delivered by trained and quality-assured facilitators over six months through 3 face-to-face contacts, 2 telephone contacts and written materials. The control group will have the same number of contacts with facilitators and general issues about feeding will be discussed. The primary outcome is change in weight standard deviation score from birth to 1 year. Secondary objectives are to quantify the effects of the intervention on infant energy intake and diet at age 8 months and changes in infant adiposity during the first year of life.

Planned Impact

The rising prevalence of childhood obesity is a major public health challenge for the 21st century. Being obese increases the risk of diabetes, hypertension, cardiovascular disease and cancer. It can also impair a person's well-being, quality of life and ability to earn. The Foresight Report predicted that if previous trends continued, nearly 60% of the UK population could be obese by 2050. The economic implications would be substantial. By 2050 there would be a seven fold increase in direct healthcare costs of overweight and obesity, with wider costs to society and business reaching £45.5 billion per year (at 2004 prices). If the Baby Milk trial shows that targeting infancy weight gain is effective in reducing the burden of obesity, it has the potential to benefit the whole of society. Changing the recommendations on formula-milk tins has the potential to be a low-cost universal intervention leading to population level changes in dietary behaviour and subsequent obesity risk.

Policy makers will benefit in setting future recommendations for infant feeding guidelines. For example the current recommendation is to feed a baby on demand and many parents take this to mean that the baby should be fed every time she/he cries. This could result in overfeeding. Printed instructions on formula-milk packaging recommend 6 feeds per day of 90mls per feed from birth, while breastfed babies get only 8mls per feed in the first few days of life and more frequent feeds. These differences could potentially programme formula-milk fed babies to expect larger portion sizes and calorie loads.
Future parents will benefit as the study could inform consistent, practical and acceptable infant feeding guidelines. The information generated could inform health visitor training and information booklets on infant feeding.

The trial will address the key question of ability to promote healthy growth in infancy and the cohort is also highly suitable for follow up, to improve understanding of he causal mechanisms of childhood obesity. The detailed diet and phenotypic data available in this cohort will be complementary to the UK 2012 Birth Cohort. There are very few research teams working on this important area. This will give the UK a lead in research into childhood obesity by focussing on formula-milk intake. We are not aware of any other studies with such detailed measures of infant diet, maternal correlates of infant feeding and infant growth throughout the first year of life.

The immediate beneficiaries will be the 700 parent-infant dyads recruited to the study. In our questionnaire validation study, 44% of the mothers tightly packed the formula-milk scoops which could lead to over concentrated feeds and excess weight gain. Parents will be given support and advice regarding formula-milk feeding, weaning and growth monitoring so that the babies do not become overweight or obese. This could have long term consequences for better health.

The trial will also promote a greater awareness of the importance and conduct of community-based child health research in primary care. We have presented and discussed the trial to local health visitors, midwives and the primary care research network team who will actively promote the study to eligible participants. This has improved their knowledge and understanding of good clinical practice with regard to clinical research. As the study progresses we will keep them informed of the emerging findings through regular contacts at their team meetings and through updates in their newsletters.

Staff employed on the study will benefit from the training they will receive. All investigators will benefit due to the novel nature of the intervention and its evaluation.

In summary, this trial is of great interest and potential benefit to parents, paediatricians, health visitors, GPs, public health doctors, Department of Health and other research units developing interventions to prevent childhood obesity.

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