Objectives Birth outcomes in migrants vary, but the relative explanatory influence of obstetric practice in origin and destination countries has been under-investigated. To explore this, birth outcomes of Scots and Polish migrants to Scotland were compared with Polish obstetric data. Poles are the largest group of migrants to Scotland, and Poland has significantly more medicalized maternity care than Scotland. Study design A population-based epidemiological study of linked maternal country of birth, maternity and birth outcomes. Methods Scottish maternity and neonatal records linked to birth registrations were analysed for differences in modes of delivery and pregnancy outcomes between Polish migrants and Scots, and compared with Polish Health Fund and survey data. Results 119,698 Scottish and 3105 Polish births to primiparous women in Scotland 2004–9 were analysed. Poles were less likely than Scots to have a Caesarean section and more likely to have a spontaneous vaginal or instrumental delivery. The Caesarean section rate in Poland is significantly higher and instrumental delivery rate lower than for either group of women in Scotland. Conclusions Methodologically, comparing a large group of migrants from one country with the host population has advantages over grouping migrants from several countries into a single category, and allows more informed analysis of the effect of health services. Polish mothers' being slightly healthier explains some of their lower Caesarean section rate compared to Scots in Scotland. However, dominant models of obstetrics in the two countries seem likely to influence the differences between Poles delivering in Poland and Scotland. Further investigation of both is required.