This study aimed to compare differences in low birthweight (LBW, < 2500 g) between the offspring of Swedish-born women and migrant women from the Global North and Global South, while simultaneously considering the role of other social factors. We used total population registers to study resident women who gave birth in Sweden between 1997 and 2016, representing a total of 1,917,171 live births. Logistic regression analyses were performed using two analytical approaches: (1) a standard approach, applying regression models to assess the association between region of birth and LBW while adjusting for social factors; and (2) an intersectional approach, with an additive combination of region of birth, income, and parental support variables. Both approaches yielded odds ratios (OR) with 95% confidence intervals (CI) and were adjusted for year of birth, maternal age, and parity. Results from both approaches showed differences in the odds of LBW according to maternal background. Importantly, findings from the intersectional approach demonstrated that women from the Global South had consistently higher odds of LBW across income levels, but with risks amplified among those living alone. These findings show that maternal migration background is a strong determinant of LBW, and that its impact is differentially compounded by social factors.