fertility rates in the United States are near historic lows. One reason is a sharp decline over the last three decades in the number of American women having babies in their 20s. And yet there's been no change in women's biology or the age at which fertility declines.Unsolvable problem. Enter egg freezing. Freezing embryos for in vitro fertilization IVF has been possible for decades.But freezing unfertilized eggs was a tougher scientific challenge. used initially for patients with cancer and other condition ...