שינויים

לא ידוע האם תרבויות היסטוריות היו מודעים לכך שחלק מהמחזור החודשי הוא הפורה ביותר. בשנה 388 כתב אוגוסטינוס על התנזרות תקופתית. בהתייחס לחסידיו של מאניכאיזם, דתו לשעבר, הוא אמר "האם זה לא אתה שנהג לייעץ לנו לבחון עד כמה שניתן את הזמן שבו אישה, לאחר טיהורה, עשויה להרות, ולהימנע ממגורים משותפים בתקופה זו ...?".אם המאמינים במאניכאיזם פעלו באופן דומה למצוות היהודים בנוגע ל[[וסת|ווסת]],  

 It is not known if historical cultures were aware of what part of the menstrual cycle is most fertile. In the year 388, Augustine of Hippo wrote of periodic abstinence. Addressing followers of Manichaeism, his former religion, he said, "Is it not you who used to counsel us to observe as much as possible the time when a woman, after her purification, is most likely to conceive, and to abstain from cohabitation at that time...?"[8] If the Manichaieans practiced something like the Jewish observances of menstruation, then the "time... after her purification" would have indeed been when "a woman... is most likely to conceive."[9] Over a century previously, however, the influential Greek physician Soranus had written that "the time directly before and after menstruation" was the most fertile part of a woman's cycle; this inaccuracy was repeated in the 6th century by the Byzantine physician Aëtius. Similarly, a Chinese sex manual written close to the year 600 stated that only the first five days following menstruation were fertile.[9] Some historians believe that Augustine, too, incorrectly identified the days immediately after menstruation as the time of highest fertility.[10]