Introduction Historically South Asian babies are of low birthweight and lighter than their European counterparts. It has been reported that Japanese nationals who immigrated to the US increased in size until they were similar to their native American counterparts. It has been anticipated this will occur among Asian children born in the UK.

Aims (1) To determine the secular trend over a 20 year period (1986–2006) for the mean birthweight of South Asian babies born in UK vs their European counterparts. (2) To determine if ethnicity or any maternal factor had a significant effect on birthweight.

Methods The birthweight of five subgroups of South Asian babies and European babies were studied over a 1 year period and compared to a similar study 20 years ago.

Results 402 babies were studied: 268 European and 134 South Asian origin. The mean birthweight in all subgroups of South Asians has not increased in the last 20 years. Mean birthweight remained highest in European babies(3.32 kg) and lowest in Hindus and Muslim Gujarati subgroups(3.04 kg). Maternal predictors of birthweight were BMI, cigarette smoking, parity and not ethnicity.

Conclusion Recent UK research shows low birthweight predisposes to type 2 diabetes, hypertension, coronary artery and renal disease in later life. Further studies delving into this persistence of lower birthweight in babies of South Asian origin in UK are necessary so that strategic health measures can be implemented to reduce the risk of both perinatal and long-term morbidities. It will be useful to see if this trend is evident in other European countries as well.