My coworker asked if I was pregnant, and I wasn't. The confrontation made me spiral, and I debated whether to tell my boss.

• A coworker asked me if I had the "nine-month flu," but I wasn't pregnant.
• The invasive question made me spiral, so I started working out more.

As a married woman in my early 30s, there are places where I would expect to discuss whether I'm expecting a baby. An appointment with my gynecologist is one; in conversation with my husband is another. However, getting this question from a colleague at work caught me completely off guard.

It happened when I returned to the office after working from home for several days because I'd been fighting a cold. As I logged in to my computer, a coworker appeared at my desk. When she asked how I felt, I reassured her I was on the mend.

"Do you have the nine-month flu?" my coworker asked playfully.

Her words sank in, and I felt my face flush. I was shocked and mortified because I was not pregnant.

"No, it's definitely not that," I replied.

Surprisingly, I found it difficult to handle the situation from there, but I learned a valuable lesson about boundaries in the workplace.

I became self-conscious in the workplace

After the exchange with my coworker, I attempted to return my focus to my work. But I couldn't stop thinking about the audacity of her question. Her insensitive words stung as they replayed in my head.

I also wondered: Had I gained weight? Perhaps my blouse didn't look as flattering on me as I thought it did in the mirror. Did I look especially tired? I had just recovered from a cold.

In the wake of my coworker's comment, I found myself doubling my gym workouts and second-guessing my clothing choices. I even started working overtime, putting extra effort and polish into my assignments as I fully recovered from my flu to dispel any false impressions.

I wondered if I should talk to my boss about it

In the days after, I wondered if I should talk to HR or my boss about the situation. I searched the internet for information about how to handle the situation but came up empty-handed. When I confided in my close friends about the experience, they agreed my coworker was out of line. My husband empathized but advised me to brush off the comment and not let it bother me.

Still unsettled, I finally decided to inform my supervisor about the incident, hoping the experience wouldn't happen to other women in the workplace.

I didn't want to appear to be a petty tattletale, so I was relieved that my conversation with my supervisor opened the door to a larger discussion about establishing personal boundaries.

I'm now implementing hard boundaries at work

As a child-free woman in my mid-30s, I realized I needed to better prepare myself for any future unsolicited inquiries about my plans for reproduction.

I found a sense of comfort and community in reading Ruby Warrington's "Women Without Kids: The Revolutionary Rise of an Unsung Sisterhood." The book is part memoir and part anthropological study of the various factors driving the global decline in the birth rate. Warrington encourages parents to read the book as well to learn how to become better allies to child-free women in today's society.

If the question comes again, I will be ready with a different strategy: simply ask the coworker why she wants to know.

That's how Ketta Crawford, the vice president of people operations at The Mom Project — a digital community dedicated to building a better workplace for women, parents, and the businesses they support — told me she would handle the situation.

If answering the question is still uncomfortable, Crawford added she might opt for simple language that sets a firm boundary, such as, "Thanks for asking, but that is a personal matter that I am not comfortable answering at this time."

And that's something I will keep in mind as a child-free woman.