BACKGROUND: Numerous studies have highlighted poorer reproductive and perinatal health outcomes among migrant mothers in developed countries. Due to the fact that no conclusive data is currently available at national level in Spain, this study aimed to explore potential differences by comparing the prevalence of low and multiple live births and the proportion of live births by maternal age and country of origin during 1996-2006. METHODS: A cross-sectional study was conducted using data from the National Statistics Institute. Low birthweight (LBW) was compared by mothers' country of origin using a logistic regression model. Odds ratios (ORs) and their respective 95% confidence intervals (CIs) are stratified by multiplicity and maternal age. RESULTS: LBW was associated with a combination of older maternal age and multiple pregnancies in the case of women who had been born in Europe (EU15). However, this association was not found in women who originated from outside the EU15, mostly from countries who have shown significant emigration to Spain during the last decade. LBW was present among all age groups, in both singleton and multiple births, and in particular Romanian mothers showed the highest OR 2.34 (95% CI 1.20-4.80). CONCLUSION: This study confirms differences in the reproductive pattern and LBW depending on maternal country of origin. These results allow a better understanding of the reproductive pattern and the implications of mothers' country of origin in LBW. Thus, helping health decisions makers to plan future health interventions aimed at reducing the LBW prevalence in Spain.