I would disagree. “Progression of the courses” seems to apply to “Unmarried women” which...if it were menstrual cramps, would that not apply to all women?
The tendency is for menstrual problems to diminish over time, being most severe in adolescence, unless you have endometriosis.
Married women would already have an understanding of their moon cycles, therefore it would be unnecessary to advise them.
Read the text as printed here:
Now I am upon Female Infirmities, it will not be unseasonable to touch upon a common Complaint among unmarry'd Women, namely the Suppression of the Courses. This don't only disparage their Complexions, but fills them, besides, with sundry Disorders. For this Misfortune, you must purge with Highland Flagg, ( commonly called Bellyach Root ) a Week before you expect to be out of Order; and repeat the same two Days after; the next Morning drink a Quarter of Pint of Pennyroyal Water, or Decoction, with 12 Drops of Spirits of Harts-horn, and as much again at Night, when you go to Bed. Continue this 9 Days running; and every fair Day, Stir nimbly about your Affairs, and breathe as much as Possible in the open Air.
Clearly Ben Franklin was only referring to a remedy for an uncomfortable menstrual cycle.
There was an old-school thought that virgins would stop having menstrual cramps "when they got married"—i.e. that intercourse and having a baby would cure the cramps problem. There might be some basis in endocrinology for this theory for some individuals; that's above my pay grade. But I do remember hearing this wive's tale still around some years ago.
I read Franklin's "recipe" and agree that it is not about abortion, but about easing menstrual pain.
I've also read six or eight biographies of Franklin; and while he did like the ladies, some biographers believe his rakish reputation was exaggerated. There's a contemporary example with the fake news we have been inundated with as political weaponry.