New diagnostic criteria for polycystic ovary syndrome (PCOS) were proposed in Rotterdam in 2003, which expanded the previous definition that arose from an expert conference sponsored by the National Institutes of Health (NIH) in 1990. However, these newer criteria give rise to phenotypes that may not actually represent PCOS, and a simple modification of the 1990 NIH/National Institute of Child Health and Human Disease diagnostic criteria may be more consistent with currently available data. ©2005 by American Society for Reproductive Medicine.
