1. Not all twins are monozygotic after elective single embryo transfer: analysis of 32,600 elective single embryo transfer cycles as reported to the Society for Assisted Reproductive Technology 
Mario Vega, M.D., Sahar Zaghi, M.D., Erkan Buyuk, M.D., Sangita Jindal, Ph.D., H.C.L.D. 
Fertility and Sterility 
Volume 109, Issue 1, Pages (January 2018)
DOI: /j.fertnstert
Copyright © 2017 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
Breakdown of outcomes of pregnancies resulting from elective single embryo transfer in fresh and frozen IVF cycles.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2017 American Society for Reproductive Medicine Terms and Conditions