I have been using a saliva microscope for many months. I always O on day 12 or 13 and start gettin ferns on cd 7 ad they gradually increase until the day before O. This month, after being on diet, peppermint and vitex for just over 3 weeks, I am on cd 9 and have none. I still think I will o on time because of cervical signs. Does this mean my estrogen has decreased? It must, right? Since saliva ferns are directly related to estrogen?