The effects of consanguinity on gestational period and anthropometric measurements at birth were assessed in a group of 662 babies delivered in Lahore, Pakistan. Regression analysis revealed consanguinity-related declines in birthweight, recumbent length, head circumference and chest girth and in gestational period. Considered in combination with a recent report from the region linking inbreeding effects to neonatal and childhood mortality, the data suggest that the widely favoured practice among Pakistanis, at home and abroad, of marriage between close relatives may be a contributory factor in their comparatively unfavourable health profile.