A crowd of abortion opponents converged on Zena Khan outside of the Choices Women’s Medical Center in Jamaica, Queens, on a recent Saturday. As a blurred mustard sun broke through the morning haze, Ms. Khan sped past posters depicting dismembered fetuses, flip cameras trained on her face and protesters demanding that she get back in her car and leave.

She was about 15 feet from the entrance when one man inched closer.

“Don’t murder your baby!” he pleaded, jostling with the volunteer escorts from Choices who were shepherding Ms. Khan to the door. “It’s got fingers and toes. You’ll regret it.”

“Should I call the cops?” she asked the escorts, her hands flying like agitated birds around her head. “I’m not even pregnant.”

Ms. Khan, 25, had given birth to a baby girl three months earlier. She was visiting Choices for a gynecologic exam.