Kara Alaimo, an associate professor of public relations at Hofstra University, is the author of "Pitch, Tweet, or Engage on the Street: How to Practice Global Public Relations and Strategic Communication." She was spokeswoman for international affairs in the Treasury Department during the Obama administration. Follow her on Twitter @karaalaimo. The opinions expressed in this commentary are solely those of the author. View more opinion at CNN.

(CNN) Some people are questioning presidential candidate Elizabeth Warren's claim that she was basically fired from a teaching job in the early 1970s because she was pregnant. It's hard to imagine that many of them understand what it's like to be a working mother -- then or now.

Kara Alaimo

Media outlets have dug up a 2007 interview in which Sen. Warren recalled that teaching job, saying she remembered thinking "I don't think this is going to work out for me. I was pregnant with my first baby, so I had a baby and stayed home for a couple years," to suggest she left her job of her own volition. That's insane.

Whether she was fired or left because she saw the writing on the wall that her job would be incompatible with motherhood -- and who can blame her for not remembering the precise details of something that happened nearly five decades ago -- the point is that our society makes it extraordinarily tough to be a working mom, especially a new mom. It's bad now, but it was even worse when Warren had her children. She deserves credit for overcoming obstacles that her male opponents simply didn't face. And our next president, whoever that is, needs to be someone who understands these barriers.

I know because I'm a new mom. I have three graduate degrees and have been awarded tenure in my university teaching job. This means that I have much more flexibility than most working moms. Outside of classes, I can name my own office hours and manage to take my baby to the pediatrician during the workday. But, since becoming a mom last year, I've still found it incredibly tough to continue to work.

A big part of the challenge is that the cost of full-time, quality childcare rivals my own take-home pay -- and, as a university professor, my salary vastly exceeds the income of the average American and the salary of schoolteachers in positions like the one Warren held. Many women paying taxes on their own income and then paying a child care provider on the books might actually lose money by going to work -- and that's before taking account of other costs associated with jobs, like commuting and professional clothes. According to Child Care Aware of America, the average cost of child care is over $20,000 per year in most parts of the country . Yet the median income is only $56,000 per year -- before taxes.