1. Department of Biology and Wildlife, University of Fairbanks Alaska, Fairbanks, AK, USA
2. Center for Alaska Native Health Research, Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
3. Department of Epidemiology, University of Iowa, Iowa City, IA, USA
4. Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR, USA