20AF (Aunt Flo)
This one is kind of obvious, but instead of fellow women referring to their monthly periods as such or their time of menstruation, the abbreviation of AF, for Aunt Flo, makes perfect sense. Why is this important, though? We all know that one of the main signs of pregnancy is
women missing their periods, or Aunt Flo. So it's only natural that they will come to refer to it often when chatting on these online forums.
In order to prevent the excessive use of the phrase "missed period" or "late period", AF is a kind of perfect substitute. Aunt Flo, or AF, is also a common use of the reference, making it not totally out there as far as the terminology or lingo is concerned. Another common abbreviation used when referring to this train of thought is TOM, for time of month.