In an unusually frank interview, PepsiCo CEO Indra Nooyi said she doesn't think that women can "have it all," adding that a career requires women to sacrifice some aspects of motherhood.

"I don't think women can have it all. I just don't think so," she told David Bradley, owner of the Atlantic Media Company, at the Aspen Ideas Festival earlier this week. "We pretend we have it all. We pretend we can have it all," Nooyi, who has been married 34 years and has two daughters, said.

She continued:

And every day you have to make a decision about whether you are going to be a wife or a mother; in fact, many times during the day you have to make those decisions. And you have to co-opt a lot of people to help you. We co-opted our families to help us. We plan our lives meticulously so we can be decent parents. But if you ask our daughters, I'm not sure they will say that I've been a good mom. I'm not sure. And I try all kinds of coping mechanisms.

As an example, Nooyi explained she had to usually skip a Wednesday morning class coffee with other mothers at her daughter's Catholic school.

My daughter would come home and she would list off all the mothers that were there and say, "You were not there, mom." The first few times, I would die with guilt. But I developed coping mechanisms. I called the school and I said, "Give me a list of mothers that are not there." So when she came home in the evening she said, "You were not there, you were not there." And I said, "Ah ha, Mrs. Redd wasn't there, Mrs. So-and-so wasn't there. So I'm not the only bad mother."

PepsiCo Chairman and CEO Indra Nooyi addresses the audience at PepsiCo's Annual Shareholders' Meeting in Plano, Texas, in 2010.

Despite such coping mechanisms, Nooyi says there's no way to square a high-pressure career with raising kids.

"My observation, David, is that the biological clock and the career clock are in total conflict with each other. Total, complete conflict. When you have to have kids, you have to build your career. Just as you're rising to middle management, your kids need you because they're teenagers, they need you for the teenage years," she said.

One of Nooyi's solutions was to enlist her employees for help. When her daughter was young and wanted to play Nintendo, for instance, she would call Nooyi's office. A receptionist would run her through a list of questions, including, "Have you finished your homework?" If her daughter said yes, the receptionist would give her permission to play Nintendo for 30 minutes.

In addition to discussing parenting, Nooyi also relayed an anecdote about her own mother. When Nooyi found out she would be named president of PepsiCo in, she says she headed home early — at 10 p.m., instead of midnight — to share the news.