An increasingly popular genetic-screening test is offering new hope to older women trying to get pregnant through in-vitro fertilization. The procedure, offered by three Colorado fertility clinics, examines cells from 5-day-old embryos to determine which are likeliest to become healthy full-term babies. Fertility specialists say the new test, which evaluates a larger number of chromosomes than other practices, is significantly more promising for women in their late 30s. And it might be safer for embryos, which have been more routinely tested at a fragile three days. “It is as if we are turning back the biological clock for women ages 38 to 42,” says William Schoolcraft, director and founder of the Colorado Center for Reproductive Medicine. For such women as