1. Center for Population Health Research National Institute of Public Health Cuernavaca Mexico
2. Political, Population and Health Research Center, School of Medicine National Autonomous University of Mexico Mexico City Mexico
3. National Perinatology Institute Health Ministry Mexico City Mexico
4. Reproductive Health Division, Center for Population Health Research National Institute of Public Health Mexico City Mexico
5. School of Public Health of Mexico National Institute of Public Health Cuernavaca Mexico
6. Division of Cancer Epidemiology McGill University Montreal Canada
7. National Institute of Public Health Cuernavaca Mexico