Explaining differences in birth size and adiposity between Pakistani and White British babies

There is a growing recognition that being born 'small is associated with an increased risk of poorer adult cardiometabolic health in addition to its known adverse effects on perinatal and infant outcomes. Previous studies have shown markedly lower birth weight among infants of South Asian origin compared to those of White British origin and there is a suggestion that such differences may mask greater central adiposity in South Asians. In this thesis, differences in birth size between 2221 Pakistani origin and 1838 White British origin infants born in the same UK maternity unit are described and whether the magnitude of any differences . changes depending on whether the parents (both mother and father) and grandparents of Pakistani infants were born in the UK or South Asia was investigated. Marked differences in birthweight between Pakistani origin and White British origin infants persisted even after adjustment for a wide range of potential masking and mediating characteristics. Important differences remained whether both parents were UK born, one was South Asian born or both were South Asian born, suggesting that at least over two generations, environmental or lifestyle changes amongst parents who have migrated to the UK and spent all of their life here have not had a major impact on these differences. Despite their smaller birth weight, South Asian infants had more total body fat than White British infants, as indicated by skinfold thickness and cord leptin, which has important implications for any public health interventions aimed at increasing birthweight in South Asian infants, as this could result in greater body fat· and ultimately poorer cardiometabolic health