Our paper compares the birth outcomes of international migrant women in Germany to those of non-migrant women. In Germany, about one-third of all newborns are born to migrant mothers. Since immigrant status and socio-economic disadvantages are highly correlated, the health of migrant children and their mothers has received increasing attention in the international literature. When investigating perinatal outcomes, the evidence on the effect of the immigrant status of the mother on the birthweight of her child has been contradictory. We use the sample of newborns collected by the German Socio-Economic Panel (SOEP), which contains pre- and perinatal variables that allow us to analyse the determinants of adverse birthweight outcomes. The data are on 1641 births that occurred between 2001 and 2010. Our study investigates the risk for children to be born with low or high birthweights (LBW and HBW) and small and large size for gestational age (SGA and LGA) by applying logistic regression analyses. We find that immigrant status is associated with a lower prevalence of low birthweight (LBW) and at the same time with a higher prevalence of increased prenatal growth (LGA). Control variables of the mother – age, parity, height, BMI, education, and smoking – cannot explain the birthweight differences between migrants and non-migrants. The findings support recent assumptions in the literature that the risk of low birthweight among newborns of migrant mothers has been levelling off. However, our results also suggest that new disadvantages of immigrants result from large size for gestational age, which increases the child’s risk of overweight later in life.