Every couple of months, Derpy visits the hospital for an appointment that only she and her roommate know about. Since the start, she's convinced Dinky that she's simply had some errands to run.

However, one day she believed that her daughter should learn the truth about where she goes and why. What has Derpy been hiding from her, and what could it mean for Dinky?

(Equestria Daily 05/05/12)