Timing is everything in the human embryo

A noninvasive imaging method for predicting how human embryos will develop may improve the success and safety of in vitro fertilization.

Humans may be the least fertile mammals on earth 1,2. Although in vitro fertilization (IVF) technology has helped many couples—an estimated 3 million IVF babies had been born worldwide by 2002—its success rates are low (~25% per procedure), and it has led to an epidemic of high-risk multiple births3,4. In this issue, Wong et al. 5 report a noninvasive strategy for evaluating human embryos that could both improve IVF success rates and decrease the likelihood of multiple gestations. Using time-lapse videography, they discovered characteristics of initial cleavages that predict successful development to the blastocyst stage with >93% accuracy.