The ticking of a woman's biological clock just got a lot quieter with the first known birth in the U.S. conceived from a frozen egg. It may stop altogether if turns out doctors can replicate a new technique that freezes a woman's eggs without rupturing the cells. A few other researchers worldwide had announced similar results over the past decade, but no one had successfully been able to repeat the experiment. If the procedure invented at Atlanta's Reproductive Biology Associates clinic holds up, women could freeze eggs while in their early twenties, when they are the most fertile, and have their children much later in life. While this frees women from many of the biological constraints that currently make having children later in life a dicey proposition, the generational and societal hurdles involved in raising a child born to a 60-year-old mother may be harder to overcome.