1 Department of Anthropology, Oregon State University, Corvallis, Oregon.
2 Epidemiology Program, College of Public Health & Human Sciences, Oregon State University, Corvallis, Oregon.
3 Department of Family and Community Medicine and Department of Obstetrics and Gynecology, University of New Mexico School of Medicine, Albuquerque, New Mexico.
4 Division of Midwifery, Department of Family Practice, University of British Columbia, Vancouver, British Columbia.