Differences in growth and adiposity between UK Pakistani and White British children: the causes and consequences of smaller size and greater adiposity

Size at birth and growth in childhood are thought to be important stages of development in our lifespan and are known to be important to the risk of infant and childhood health and development problems. Over recent years these important phases of early development have also been linked to our risk of illness in later life, particularly diabetes and coronary heart disease. South Asian populations are known to be at particular risk of diabetes (2 – 4 fold higher) and coronary heart disease (50 – 80% higher) and this may be due to them having a tendency for more fat compared to lean mass. At birth, South Asian babies are generally smaller and lighter but recent studies show that like South Asian adults, they have more fat than White British individuals. This greater fatness for a given weight could be very important to the risk of diabetes and coronary heart disease but so far the reasons for it are not very clear. It is possible that being diabetic during pregnancy, which is more common in South Asian women, ‘overfeeds’ the infant leading to greater fatness at birth and possibly throughout life. If this is true then later generations would also overfeed their infants during pregnancy and a cycle of poor health and development could be set in motion. This continuation of risk could be made worse by the changes in environment and lifestyle experienced by South Asians who migrate to the UK such as the availability of high energy diets, a culture of less exercise and rising rates of obesity. How patterns of growth from birth to childhood differ in South Asian and White British children could also affect differences in health between these two groups in relation to childhood infections and other childhood health problems and could even affect how well children do in school. However research in this area has often used poorly designed studies with too few participants to give accurate results.

Using data and information from the Born in Bradford birth cohort study I will:

1.Look at whether how much a woman weighs at the start of pregnancy, how much weight she gains during pregnancy, her glucose (sugar) levels in pregnancy and whether she develops gestational diabetes, affect how much her child weighs and how fat they are at birth and also at age 4/5 years. I will look at whether the effect of any of these measurements is different depending on whether the mother and child are of Pakistani or White British origin.

2.Describe patterns of growth and differences in adiposity and blood pressure in UK born Pakistani origin children and UK born White British children

3.Look at whether different patterns of growth in UK born Pakistani origin and UK born White British children result in different rates of childhood infection and hospital admissions between these two groups. I will also look at whether different patterns of growth affect how well the children do in school.

4.Find out whether weight and fatness at birth and in childhood is different depending on whether parents and grandparents of Pakistani infants are born in the UK or South Asia.

To do this I will combine existing information from the BiB cohort with new information collected for the first time as part of this proposal. I will train and support school nurses in Bradford to collect skinfold measurements (used to estimate fatness) and blood pressure alongside the height and weight measurements recorded for all reception age children in the UK, including good coverage in Bradford. These measurements will be collected over 2 consecutive school years (2013/2014 and 2014/2015) and will involve approximately 8000 children. Cord blood samples for the whole BiB cohort will be used to compare fat mass in Pakistani and White British infants at birth (approx 9000 samples). In addition I will merge information from routine health and education systems with the existing BiB data.