Background: Existing literature finds that the mean birthweight of immigrant populations in Western countries is lower than that of the native population and does not systematically converge over generations in the host country. This suggests that changing environmental, social, and lifestyle conditions of immigrants and their descendants has limited impact on the birthweight of their offspring. This study contributes to the literature by examining immigrant-native birthweight differences over two generations of immigrant groups born in Sweden using total population registers with multigenerational linkages.

Methods: Children born in Sweden during the period 1987-2011 (G3) are linked to their mothers (G2), born in Sweden during the period 1973-1995, and their maternal grandmothers (G1) who are native or foreign-born. First, immigrant-native birthweight differences are examined for both G2 and G3 by country of ancestry. Second, G3 immigrant-native birthweight differences are examined by country of ancestry while accounting for factors that theoretically explain the differential. All analyses are conducted using linear regression.

Results: The results show that particular immigrant populations experience increasing birthweight disparities relative to natives over generations, while others display a convergence or no change. These differences only partially attenuate in the fully adjusted models.

Conclusion: The populations that display an increasing disparity over time are those from less developed origins that have traditionally struggled to integrate into Swedish society. It is not possible to identify the specific mechanisms behind birthweight changes over generations in the current study; however, some potential explanations include epigenetic processes or stresses related to social isolation.