This article investigates trends in low birthweight singleton live births by mother's country of birth. 11.4 million birth records from registration data in England and Wales from 1983 to 2001 were used. The analysis focuses on births to mothers born in the UK and countries that contribute to the main ethnic minority groups in England and Wales. The results show that the prevalence of low birthweight babies varies by mother's country of birth. Important differentials also exist by mother's age at birth, multiplicity and registration status.