Sponsored by Kotex, Marjorie May Learns about Life is a somewhat scientific approach to the details of menstruation, pregnancy, and childbirth, framed as a discussion between Marjorie and her mother, triggered by the appearance of Mrs Sherman's new baby.
The Mary Pauline Callender who is listed as the author of this work and of Marjorie May's Twelfth Birthday appears to be a fictional creation of the Kotex company.
'Concluding that its scientific aura was sufficiently established, Kotex dismissed the formidable "Ellen J Buckland, Registered Nurse" and engaged the friendlier, chattier, "Mary Pauline Callender" to sign its advertising copy.'
Source: Marchand, Roland. Advertising the American Dream. U of California P, 1985.