Is the salivary "ferning" a reliable index of the fertile period?

We found that the fern leaf crystallisation of human saliva is a non-specific phenomenon, independent on the action of estrogenic hormones. Salivary ferning can be obtained in practice during the whole menstrual cycle and occurs in the saliva of postclimateric, pregnant and prepuberal women. Even the saliva of male subjects gives invariably the ferning reaction. In conclusion, salivary ferning does not seem a reliable method to establish woman fertile period.