Pacing in her jail cell, Diana Sanchez knew she was about to go into labor. She had been experiencing contractions for nearly five hours.

Security footage showed Ms. Sanchez knocking on the cell door for help just before 10 a.m. on July 31, 2018, but all she got was a thin, white mat slid under the door. For an hour, Ms. Sanchez had contractions, writhing in pain and screaming for help, the footage showed.

Ms. Sanchez, 27, gave birth alone in the cell and with no medical supervision or treatment, according to a federal lawsuit filed on Wednesday against Denver, Denver Health Medical Center and several nurses and deputies.

“What should have been one of the happiest days of her life was instead a day of unnecessary terror, pain, and humiliation,” the lawsuit said.