Results regarding the “healthy migrant” effect in birth outcomes are somewhat inconclusive regarding migrants living in developed countries. While several studies have found as good or better birth outcomes of the foreign-born compared to the native-born, other studies report the contrary. According to the “acculturation paradox”, the length of exposure to the host country can be positively correlated with adverse birth outcomes, inter alia due to more stressful living situations in the host country.

Nevertheless, there are no studies investigating the impact of stress induced by international migration itself. Thus, we propose to compare mothers of different migratory status’ giving birth in Switzerland between 2010 and 2014 and to test for their birth outcome, that is low birth weight and preterm births. The analyses are based on Swiss longitudinal register data and on logistic regression analyses. Switzerland presents an interesting case to study. In 2014, a high 6,7% of all infants born were of low birth weight; a situation that is somewhat due to the large foreign-born population residing in Switzerland.

First results indicate a healthy migrant effect for migrants that arrived during the third trimester of pregnancy. Stress only seems to result in low birth weight (and not in preterm delivery) when migrating during the first and second semester of pregnancy. Finally, the “acculturation paradox” also seems to apply to the Swiss context, where pre-pregnancy migrants with a duration of residence of at least ten years present the highest risk of adverse birth outcomes.