A human woman of about 70 years of age in 2270, Dr. Sarah April is the wife of Commodore Robert April, and also served as the chief medical officer of the U.S.S. Enterprise during Robert April's tenure as the starship's first commander. Sarah April designed many of the medical instruments commonly used in the 2260s on Federation starships.
On stardate 6770.3 (2270), Dr. April was accompanying her husband to the Babel planetoid where his formal retirement ceremonies are to be held, per Starfleet regulations mandating that human officers retire at the age of 75. Because of their already advanced ages, the Aprils weren't debilitated by the reversed time-flow of the parallel antimatter universe in which the Enterprise became temporarily trapped during the voyage to Babel; instead, they were returned to the prime of their lives. The heroic manner in which the Aprils took command of the starship to get the vessel safely home after all other personnel aboard had grown too young to handle the controls motivated Starfleet to loosen its mandatory retirement rules. Because neither Sarah April nor her husband harbored any regrets over how they had spent their lives, they opted to use the Enterprise's transporter to return them to their normal ages following their return from the antimatter universe.