I realize I'm about to step in it. And by "it," I mean the "Marissa Mayer is a female CEO -- and she's pregnant!" discussion that inevitably leads back to the "Can women have it all?" exchange that began last month.

As a single woman who does not have children, I already shared some thoughts on "having it all" here. I was trying to hold back on this new hot topic, but a PR pitch I received this morning pushed me right into it. It read:

So, you're not Marissa Mayer, 37-year-old newly minted CEO of Yahoo! and six-months pregnant with her first child. The picture of success for the modern woman. Can you still have it all? What lessons can be learned by Marissa's meteoric rise to the top of the business world? How can women yearning to get ahead without sacrificing family life emulate Marissa or make the best choices for themselves?

The next line was a pitch for a hair care product, because naturally, the best way to become CEO and get pregnant is with "gorgeous hair." But putting the idiocy of the PR pitch aside, are we now saying that Marissa Mayer is successful because of this equation: CEO + Mother-To-Be = Success? If it had been simply this one PR pitch, I would have put it aside. But the conversations this week around Marissa being a mother (to-be) on top of being a female CEO were already beginning to wear on me. Whatever future success I had with my career and my business, would I ever be seen as a true modern woman success story without also juggling motherhood?

Nearly 50 percent of American women are childless. While the majority of women -- about 80 to 85 percent -- become mothers eventually, most highly educated, high-income earning women like Marissa Mayer have their first baby later in life. Marissa, who turned 37 in May, will be one of the 14 percent of first-time moms who have a first birth at age 35 or older. And in general, Marissa and her college-educated cohorts are more likely to get married later than the national average (Marissa was married in 2009) and are most likely to become mothers only once married. (Only 2 percent of women age 35 and older were single at first birth in 2008, although that number is expected to grow.)

It was the line: "The picture of success for the modern woman" that really got me. Not all women can be mothers. Not all women want to be mothers. Not all women will be mothers. And not all women should be mothers. So as long as we pin "success for the modern woman" with motherhood, we will undermine some of the most gifted women in this country -- and those girls and women who aspire to be like them. Is Oprah Winfrey not a success? Is Supreme Court Justice Sonia Sotomayor not a success? Is the former United States Secretary of State, Condoleezza Rice, not a success?

Furthermore, Marissa has had the good fortune and ability to fall in love, get married and conceive a child, but she's not actually yet a mom. Does simply being pregnant while having an extraordinary career make you a greater success as a woman?

I have sincere respect for mothers (all mothers -- working mothers, stay-at-home mothers, etc.) and I always expected and wanted to be a mother myself. I support the challenges moms face having to or wanting to do things outside the context of motherhood. But when we say that success is only achieved when one does those things along with being a mother, we cast aside the women who are not mothers as if they are not eligible to be a "picture of success for the modern woman."

I wish Marissa all the best in all her endeavors, personal and professional. Success is relative to each person's potential. And I have a feeling she's only just begun.