(FORTUNE Magazine) – You've probably heard of the latest disease to strike high-level businesswomen: "an epidemic of childlessness." So says Sylvia Ann Hewlett, an economist whose Creating a Life: Professional Women and the Quest for Children is generating buzz on TV talk shows and in Time and People cover stories.

We wonder: What planet is she on?! The reason we ask is that Hewlett's statistics--49% of women earning over $100,000 are childless after 40--don't jibe with our findings. In a survey of 187 high achievers who gathered in March at FORTUNE's Most Powerful Women in Business Summit, 71% have children. The average kid count is 2.2 per powerful woman.

Apparently, FORTUNE's bigwigs have figured out the having-it-all thing better than the women in Hewlett's survey. In fact, the vast majority of those we talked to don't buy her theories. Southwest Airlines President Colleen Barrett says, "We have far more women at Southwest today having babies and continuing to work than ten years ago." Lehman Brothers' Barbara Byrne notes that eight of ten female managing directors in her investment-banking division have kids--"and most more than one." Byrne herself has four. Even Ann Moore, the executive at Time Inc. (FORTUNE's parent) who oversees Time and People, says, "If there is an epidemic of childlessness, why do I have 23 professional women on maternity leave and another 33 who will be taking off this year? A byproduct of female leadership, maybe?"

Maybe. Or perhaps these women have discovered ways to combine babies and careers; 30% of the women who attended our summit have househusbands; some launched into motherhood early--Barrett at 23 and Oxygen Media CEO Geraldine Laybourne at 24 (as Hewlett advises). But most just juggled adeptly--the typical woman in our survey became a mom at 31. "I used to say early or late is fine, but the middle is a killer," says Allen & Co. managing director Nancy Peretsman. "Early in any career, there are seven to ten years where you have to prove yourself." Peretsman became a mom at 34, just as she made partner at Salomon Brothers, her former employer.

Although waiting is risky, these women have the resources to capitalize on technological advances. Dawn Lepore, a vice chair at Charles Schwab, conceived her first child, a son, in vitro and gave birth at age 44. Now, four years later, Lepore is caring for her newborn daughter, conceived in vitro and carried by a surrogate. "Technology and society give us a choice--have kids or not, and when," says Anne Stevens, Ford's head of North America vehicle operations.

Choosing is often painful, but the upside is that women have more options than ever. Former Texas governor Ann Richards, now a senior advisor with Public Strategies, says, "If women are choosing not to have children, I think it's great. They will have more freedom to pursue careers, interests, joys." Ever blunt, the influential mother of four adds, "This have-a-baby guilt trip is ridiculous."