1. School of Epidemiology & Public Health, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON,K1G 5Z3, Canada
2. Canadian Forces Health Services Group, Department of National Defence, National Defence HQ (Carling), 60 Moodie Drive, Ottawa, ON K1A 0K2, Canada
3. CHEO Research Institute, Children Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada
4. Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada
5. Department of Health Sciences, Carleton University, 2305 Health Sciences Building, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
6. Centre for Fertility and Health, Norwegian Institute of Public Health, Postbox 222 Skøyen, N-0213 Oslo, Norway