Listen to a successful woman discuss her failure to bear a child, and the grief comes in layers of bitterness and regret. This was supposed to be the easy part, right? Not like getting into Harvard. Not like making partner. The baby was to be Mother Nature’s gift. Anyone can do it; high school dropouts stroll through the mall with their babies in a Snugli. What can be so hard, especially for a Mistress of the Universe, with modern medical science devoted to resetting the biological clock? “I remember sitting in the clinic waiting room,” recalls a woman who ran the infertility marathon, “and a woman–she was in her mid-40s and had tried everything to get pregnant–told me that one of the doctors had glanced at her chart and said, ‘What are you doing here? You are wasting your time.’ It was so cruel. She was holding out for that one last glimpse of hope. How horrible was it to shoot that hope down?” The manner was cold, but the message was clear–and devastating. “Those women who are at the top of their game could have had it all, children and career, if they wanted it,” suggests Pamela Madsen, executive director of the American Infertility Association . “The problem was, nobody told them the truth about their bodies.” And the truth is that even the very best fertility experts have found that the hands of the clock will not be moved. Baby specialists can do a lot to help a 29-year-old whose tubes are blocked or a 32-year-old whose husband has a low sperm count. But for all the headlines about 45-year-old actresses giving birth, the fact is that “there’s no promising therapy for age-related infertility,” says Dr. Michael Soules, a professor at the University of Washington School of Medicine and past president of the American Society for Reproductive Medicine . “There’s certainly nothing on the horizon.” This means, argues economist Sylvia Ann Hewlett in her new book, Creating a Life: Professional Women and the Quest for Children , that many ambitious young women who also hope to have kids are heading down a bad piece of road if they think they can spend a decade establishing their careers and wait until 35 or beyond to establish their families. Even as more couples than ever seek infertility treatment–the number of procedures performed jumped 27% between 1996 and 1998–doctors are learning that the most effective treatment may be prevention, which in this case means knowledge. “But the fact that the biological clock is real is unwelcome news to my 24-year-old daughter,” Hewlett observes, “and she’s pretty typical.” Women have been debating for a generation how best to balance work and home life, but somehow each new chapter starts a new fight, and Hewlett’s book is no exception. Back in 1989, when Felice Schwartz discussed in the Harvard Business Review how to create more flexibility for career women with children , her proposals were called “dangerous” and “retrofeminist” because they could give corporations an excuse to derail women’s careers. Slow down to start a family, the skeptics warned, and you run the risk that you will never catch up.