1. What is a difficult transfer
What is a difficult transfer? Analysis of 7,714 embryo transfers: the impact of maneuvers during embryo transfers on pregnancy rate and a proposal of objective assessment 
Alejandro Kava-Braverman, M.D., Francisca Martínez, Ph.D., Ignacio Rodríguez, B.Sc., Manuel Álvarez, M.D., Pedro N. Barri, Ph.D., Buenaventura Coroleu, Ph.D. 
Fertility and Sterility 
Volume 107, Issue 3, Pages e1 (March 2017)
DOI: /j.fertnstert
Copyright © 2016 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
Clinical pregnancy rate and OR of CPR with additional maneuvers. *Adjusted OR for ART (IVF/ICSI in fresh embryo transfer or frozen–thawed embryo transfer), number of transferred embryos, the day of ET, physicians who performed the ETs, embryo quality, and the interaction between age and technique.
Fertility and Sterility  , e1DOI: ( /j.fertnstert )
Copyright © 2016 American Society for Reproductive Medicine Terms and Conditions

3. Supplemental Figure 1
Model for the objective classification of ET difficulty.
Fertility and Sterility  , e1DOI: ( /j.fertnstert )
Copyright © 2016 American Society for Reproductive Medicine Terms and Conditions