Clara is a labor and delivery nurse, so she has a pretty good idea of what to expect when she delivers her own twins at the same hospital where she works. But she wasn’t prepared for this.

C-sections are the most frequently performed major surgeries in the world. So why do so many patients feel severe pain during them? Season 2 of the award-winning podcast “The Retrievals” is an investigation into this underreported problem — and the new effort to solve it. Coming July 10th.

Patients at a fertility clinic experience excruciating, unexpected pain. For months the reason for that pain remains hidden. Then they get a letter from the clinic.

The patients in this story came to the Yale Fertility Center to pursue pregnancy. They began their I.V.F. cycles full of expectation and hope. Then a surgical procedure called egg retrieval caused them excruciating pain. Some of the patients screamed out in the procedure room. Others called the clinic from home to report pain in the hours that followed. But most of the staff members who fielded the patients’ reports did not know the real reason for the pain, which was that a nurse at the clinic was stealing fentanyl, and replacing it with saline. From Serial Productions and The New York Times, The Retrievals is a five-part narrative series reported by Susan Burton, a veteran staff member at “This American Life” and author of the memoir “Empty.” Susan details the events that unfolded at the clinic, and examines how the patients’ distinct identities informed the way they made sense of what happened to them in the procedure room. The nurse, too, has her own story, about her own pain, that she tells to the court. And then there is the story of how this all could have happened at the Yale clinic in the first place. Throughout, Burton explores the stories we tell about women’s pain. How do we tolerate, interpret and account for it? What happens when pain is minimized or dismissed?