LAST week, Yahoo’s new chief executive, Marissa Mayer, gave birth to a baby boy. When she was hired in July, late in her second trimester, bloggers and newspaper columnists celebrated the breaking of another pane in the glass ceiling. Pregnant women, it seemed, could be hired for top jobs. Given the many breathless and celebratory “bump watches” in tabloids, it might seem that the stigma around working while pregnant has finally lifted. The birth of Ms. Mayer’s son came only a week after the host of the Emmys, Jimmy Kimmel, introduced the actress Claire Danes with the line, “Our next presenter has a baby in her.” Ms. Danes traversed the stage in a bright yellow dress that emphasized her fertile form.

For the rich and powerful, pregnancy might not be an obstacle — it might even help one’s career. But for the rest of us, it remains a hindrance.

Although federal law prohibits companies with 15 or more employees from discriminating against pregnant job seekers, it can be quite hard for an ordinary woman to land a job if she lets prospective bosses know she is pregnant.

My own pregnant friends tend to cover up, literally and figuratively. Meeting with prospective employers, like law firms and news organizations, they hide their bumps under oversize jackets or slouchy sweaters. I met one for dinner after her job interview and she was wearing a giant, gray, cabled sweater. “I am not telling them that I am about to enter my second trimester,” she said, pointing to the heavy knit. She got the job, and when she accepted, she revealed her status, soon sensing her new boss’s displeasure.