This project was undertaken to examine the associations of a number of risk factors with impaired fetal growth, exemplified by delivery of a low-birthweight infant at term (TLBW). Utilising a large database of largely homogeneous (white) births in Wales, the Cardiff Births Survey, multivariable analysis by logistic regression examined the relative importance of these risk variables. Significant independent associations with TLBW were found (in decreasing order of magnitude) for low maternal weight, pre-eclampsia, smoking, short maternal height, late pregnancy bleeding, early pregnancy bleeding, history of a previous stillbirth, primiparity and older maternal age. In this population, risk of TBLW was associated with a number of demographic, medical and social factors. Of these, only smoking is likely to be modified by intervention.