What accounts for physical activity during pregnancy? A study on the sociodemographic predictors of self-reported and objectively assessed physical activity during the 1st and 2nd trimesters of pregnancy - Mendinueta, A. (Universidad del País Vasco. Facultad de Medicina y Enfermería) ; Esnal, H. (Universidad del País Vasco. Facultad de Medicina y Enfermería) ; Arrieta, H. (Universidad del País Vasco. Facultad de Medicina y Enfermería) ; Arrue, M. (Hospital Universitario de Donostia (Sant Sebastià, País Basc)) ; Urbieta, N. (Biodonostia Osasun Ikerketako Institutura (País Basc)) ; Ubillos, I. (Biodonostia Osasun Ikerketako Institutura (País Basc)) ; Whitworth, K. W. (Center for Precision Environmental Health. Department of Medicine. Baylor College of Medicine) ; Delclòs Alió, Xavier (University of California. Institute of Urban and Regional Development) ; Vich, Guillem (Universitat Autònoma de Barcelona. Departament de Geografia) ; Ibarluzea, Jesús (University of the Basque Country (UPV/EHU). Faculty of Psychology)