Objectives: We examined the effect of the mother's origin and socio-economic characteristics on adverse perinatal outcomes in Switzerland.

Methods: Births occurring from 2011 to 2017 were identified in the Swiss population register and merged with the Swiss civil register and the Register of the first pillar to obtain information on the migration origin and socio-economic level. Four indicators of adverse perinatal outcomes were defined.

Results: Logistic regressions show that both the migration origin and the socio-economic level are measured by the parents' income, influence risk. Compared to the children of mothers born in Switzerland, those of mothers from EU/EFTA countries have a lower risk of infant mortality, low birth weight and extreme prematurity. The highest risk is observed for children born to mothers from the rest of the world. High levels of risk consistently characterize children with low-income parents (first decile).

Conclusions: Our results justify further investigations at the level of health services to better identify the factors causing differences in the prevalence of adverse outcomes and to take them into account in adapted health policies.