Testing the Epidemiological Paradox in Spain with Respect to Perinatal Outcomes

Sol Juárez, Consejo Superior de Investigaciones Científicas (CSIC)
George B. Ploubidis, London School of Hygiene and Tropical Medicine (LSHTM)
Lynda Clarke, London School of Hygiene and Tropical Medicine (LSHTM)

This study uses Spanish data to examine the implications of applying the common threshold (2,500 grams) used to define low birth weight (LBW) to detect the presence of the epidemiological paradox, where migrant mothers have a lower probability of LBW than native-born mothers. Spain has a shorter immigration history than other countries, eg United States, where many studies have demonstrated the existence of the LBW paradox but none has given a conclusive explanation to account for it. More importantly, all focus on revealing the mechanism underlying the paradox without contemplating the possible existence of an artificial effect due to methodological bias. This pioneering paper presents a different approach to address this important research question.