1. Effect of maternal height and weight on risk of preterm birth in singleton and twin births resulting from in vitro fertilization: a retrospective cohort study using the Society for Assisted Reproductive Technology Clinic Outcome Reporting System 
Richard P. Dickey, M.D., Ph.D., Xu Xiong, M.D., Dr.P.H., Rebekah E. Gee, M.D., M.P.H., Gabriella Pridjian, M.D. 
Fertility and Sterility 
Volume 97, Issue 2, Pages (February 2012)
DOI: /j.fertnstert
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1 Flow chart of records included in study.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions