1. Multiple gestation associated with infertility therapy: an American Society for Reproductive Medicine Practice Committee opinion 
Fertility and Sterility 
Volume 97, Issue 4, Pages (April 2012)
DOI: /j.fertnstert
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
Assisted reproductive technology outcomes in U.S. related to SART/ASRM guidelines for number of embryos to transfer. Data derived from Dashed lines indicate years SART/ASRM guidelines were introduced (1998) and subsequently revised (1999, 2004, 2006, and 2008). Multiple births are expressed per delivery; twin and triplet+ pregnancies are expressed per clinical pregnancy.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions