Every few years, a new book ignites debate about structural and social impediments to women achieving professional parity.

This year, Sheryl Sandberg's Lean In: Women, Work, and the Will to Lead, due out in March, is that book, but it's also stirring up controversy about privilege. Critics want to know where Sheryl Sandberg, the Harvard-educated, billionaire COO of Facebook, gets off pressing ordinary women with ordinary educations, ordinary bank accounts, and ordinary access to child care to work harder and seize the reins of their careers.

It's worth noting that ordinary women do this every day--by starting their own companies. Entrepreneurship is an interesting lens through which to view one of Sandberg's chief arguments: that women "leave before [they] leave." Sandberg says many women are hesitant to push themselves forward--to pursue higher positions with more work and more responsibility--because they anticipate starting a family (even if they don't yet have spouses) and don't want to doom the possibility of work-life balance. Unfettered by present or future domestic bonds, men rise up the ladder in their places.

Dropping out is not an option.

But holding back isn't really an option for women entrepreneurs. In the early years, particularly, there is simply too much to do and no one to pick up the slack. Check out of your job and you hurt yourself. Check out of your own business and you risk hurting your employees, customers, and people--including family and friends--who gave you money because they believed in you. If women are likely to sabotage themselves, as Sandberg contends, entrepreneurship minimizes their opportunities to do so. Once you embark on that path--you are it, sister, whether you like it or not.

Where entrepreneurial women arguably do sabotage themselves is the decision--when it is a decision--to build smaller companies than men. Even a minnow feels like a big fish in a pond the size of a puddle. The number of women-owned businesses is growing faster than the number of new businesses overall, according to a study by American Express Open, and 30 percent of U.S. businesses are owned by women. But those enterprises account for just 6 percent of the workforce and less than 4 percent of business revenues. A report from the National Women's Business Council shows that only 1.8 percent of women-owned businesses earn $1 million or more, and 68 percent make less than $25,000.

Three reasons women build smaller.

I can think of three explanations for such under-performance. The first is external obstacles. Women in general have less access than men to capital (including venture and private equity investment and government loans), markets, and networks.

The second explanation is personal choice. Keep the company small, some women believe, and work-life balance becomes a dreamable dream. If those women were comparably un-ambitious as employees, it would damage their careers, which is Sandberg's thesis. As entrepreneurs, they may sacrifice revenue. But at least they are in control.

The third explanation is more complicated. Sandberg says that women underestimate their own abilities and don't force their way to the proverbial table. We can probably all agree that it is a bad thing when women allow low confidence and self-esteem to hold them back. But as we know from research, women are also more cautious than men, requiring better odds that the risks they take will pay off. That attitude isn't altogether bad, even though it can inhibit growth: women-owned businesses are more likely to fail to thrive; men-owned businesses are more likely to fail spectacularly.

"Leaning In" for women entrepreneurs.

Sandberg, who dwells in the citadel of aggressive entrepreneurship, would likely urge women to build responsibly but to do so in growth rather than lifestyle companies. Start the next Facebook, not a bed-and-breakfast. Choose a competitive, expansive industry and it will force you to step up your game just as starting your own company forces you to stay in the game. Always be scaling and, ideally, when you do choose to have children, you'll command sufficient resources to make things easier.

But how many of us get to experience "ideally"? When plans for ambitious growth don't pan out they erode a family's finances, not buttress them. On the flip side, women who find themselves at the helm of surging companies may repeatedly put off starting families because their obligations are too great.

The saving grace is entrepreneurs' ability to design most aspects of their businesses. Don't think about keeping the company so small it is easy to step away from. Do think about locating it somewhere that will make family logistics easier, about investing in technology that will minimize the amount of travel necessary, and about hiring people who replicate some of your skills as well as complement them. Create a culture where hard work is rewarded but being a responsible parent is always the right choice. Do that, and both you and your employees will reach heights to make Sheryl Sandberg cheer.