1. Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado;
2. Bolivian Institute of High Altitude Biology, La Paz, Bolivia;
3. Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, Utah;
4. Department of Emergency Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; and
5. Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, Colorado