A San Francisco fertility clinic has acknowledged that a liquid-nitrogen failure in one of its storage tanks may have damaged thousands of eggs and embryos—the second clinic to report such a fault in one week. The Pacific Fertility Center confirmed the March 4 incident Sunday and said hundreds of patients have been notified that their eggs or embryos may no longer be viable, and the clinic is uncertain exactly how many samples have been destroyed by the accident. In a statement, the clinic said “the vast majority of the eggs and embryos in the lab were unaffected,” but apologized to patients “for the anxiety that this will surely cause.” Separately last week, 2,000 eggs and embryos were potentially destroyed at the University Hospitals Fertility Clinic in Cleveland after a malfunction made freezers drop below their normal temperature. That incident affected around 700 families.