Ferning Test

Definition - What does Ferning Test mean?

A ferning test is a qualitative test that uses saliva to predict the time of ovulation. The increase in estrogen that occurs near the time of ovulation can dry with a fern-like pattern.

The test may not work for all women because not all women fern and those who do may not necessarily have fern-shaped saliva patter on all days of their fertile period. Additionally, ferning is often disrupted by drinking, smoking, eating, tooth brushing, and the way someone puts saliva on the glass slides.

Ferning test is also known as saliva ovulation test or saliva ferning.

FertilitySmarts explains Ferning Test

The ferning test home kit consists of a small microscope with glass slides. If you put saliva on the slide, let it dry, and then observe the slide under the microscope, you will see a full or partial fern-shaped pattern or dots and circles. The fern shape indicates that ovulation time is near.

Ovulation typically occurs around day 14 of a normal cycle. The best time to conduct a ferning test is on the following five days:

  • On the expected day of ovulation
  • Two days before the expected date of ovulation
  • Two days after the expected date of ovulation


A ferning test is only used to predict the most fertile days of a woman’s menstrual cycle. It can help with the plan to conceive; however, it doesn’t predict whether or not a woman will get pregnant. Moreover, a ferning test cannot reliably be used for the prevention of pregnancy.

A ferning test is not similar to the fertility tests that doctors use. Those tests have more reliable and consistent results.

Pros of ferning test:
It is relatively inexpensive, easily used at home, and provides greater autonomy to individuals who plan to get pregnant. It may also be beneficial if a woman has irregular periods.

Cons of ferning test:
It may give a false negative test, i.e., a woman may be near her ovulation time, but the test may show otherwise.


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