Secular trend in birth weight in native White and immigrant South Asian populations in Leicester, UK: Possible implications for incidence of type 2 diabetes in the future

Abstract

The objective was to compare birth weights between local Whites and immigrant South Asian populations in Leicester and to look for temporal trends. This was a retrospective study of labour ward records at a teaching hospital in Leicester. We examined the records of all 1852 births in 1975 (28% South Asians) and an equal sized consecutive sample in 1988 (31% South Asians). Multiple linear regression was performed to estimate the effects of the available covariates (ethnicity, maternal age, parity, gestational age at delivery and sex of the baby) on birth weight. 40-50% of the variability in birth weight could be explained by the available demographic parameters. Mean birth weight showed a significant overall increase from 1975 to 1988 (mean (95% confidence interval)) 112 (95-148) g: p < 0.0001). This trend was seen in both Whites (123 (80-166) g: p < 0.0001) and South Asians (111 (53-180) g: p < 0.0001). There was a concomitant drop in stillbirth rates in both the groups. South Asian babies were significantly lighter than Whites in 1975 (280 (225-336) g: p < 0.0001) and remained so. The lack of 'catch up' by the South Asians is not easily explained, but may reflect genetic differences, or a requirement for environmental effects on birth weight to act for longer than 13 years to be expressed fully. If birth weight is important in the genesis of type 2 diabetes, coronary heart disease and renal disease, then the higher prevalence of these diseases in the South Asian population compared with the White population will continue. Copyright (C) 2000 John Wiley and Sons, Ltd.