1. Risk factors for early miscarriage among Chinese: a hospital-based case-control study 
Guangli Xu, M.D., Yiming Wu, Ph.D., Liming Yang, M.P.H., Lu Yuan, M.D., Huafeng Guo, M.D., M.P.H., Fuqing Zhang, M.D., Yichun Guan, M.D., Ph.D., Wu Yao, Ph.D. 
Fertility and Sterility 
Volume 101, Issue 6, Pages (June 2014)
DOI: /j.fertnstert
Copyright © 2014 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
Sampling methods. (A) Sampling in objective hospitals. a: 114 cases and 228 controls from Jinshui Region Maternal and Child Health Station. b: 246 cases and 492 controls from Zhengzhou Maternal and Child health Hospital. c: 260 cases and 520 controls from 3rd Affiliated Hospital of Zhengzhou University. (B) Sampling in calendar years. No statistically significant difference was found in comparing 2010, 2011, and 2012 (P>.05). (C) Sampling in different age groups.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2014 American Society for Reproductive Medicine Terms and Conditions