In the September 2012 issue, the article entitled “Controversial egg-producing stem cells promise better IVF” (Nat. Med. 18, 1311, 2012) incorrectly stated the age range for OvaScience's first clinical trial as 35 to 42 and the anticipated time frame for commercial product launch as late 2013. The correct age range is 38 to 42, and the commercial product launch will be in 2014. The errors have been corrected in the HTML and PDF versions of the article.