1. Department of Obstetrics and Gynecology, Sainte-Justine Hospital Research Center, University of Montreal , Montreal, Canada
2. Bureau d'information et d'études en santé des populations, Institut national de santé publique du Québec , Montreal, Canada
3. Department of Epidemiology, Biostatistics, and Occupational Health, McGill University , Montreal, Canada
4. Department of Social and Preventive Medicine, School of Public Health, University of Montreal Hospital Research Centre, University of Montreal , Montreal, Canada