Getting pregnant sounds natural and almost automatic, but it often isn't. According to a 2013 study, one in six couples struggles to conceive despite a year of trying.1 For them, this seemingly natural process becomes a deliberate, planned effort — starting with tracking the fertile window. Of the many ways to do that, the saliva fern test is probably the most natural and non-intrusive.
Saliva crystals tell you your fertile window
The female body goes through a cyclical transformation every month. Estrogen rises near ovulation, and if you can spot that rise you can find your most fertile window — and the answer is in a single drop of dried saliva.
When saliva dries, it crystallises. When estrogen is elevated — 4–5 days before ovulation — the crystals take a fern-shaped form. You can observe this with a small ovulation microscope: put saliva on the glass, let it dry, and look through the lens. Depending on your cycle you might see dots and circles, full or partial ferns, or a mix.
Interpreting this yourself is hard. Ferning appears in different forms and intensities, which is why the traditional saliva fern test scores only 70–80% accuracy — not because the method is bad, but because the interpretation is difficult. The fern-crystal signal itself is over 99% accurate; the challenge is reading it consistently.
Interpret and predict ovulation with Babyndex
Babyndex, on iPhone or Android, interprets the pattern for you. Place the microscope on your phone camera, take a picture, and let the app do the rest — it uses an algorithm to score ferning and predict when your fertile window is coming.
The whole process — placing saliva on the glass, letting it dry, taking a picture and waiting for the result — takes only a couple of minutes and can be repeated day after day with the same equipment. The more images the algorithm sees from you, the better its prediction of your next fertile window.
Because it only needs a small microscope and the smartphone you already own, it is also an affordable way to learn more about your body and plan for parenthood. With Babyndex you can find out when you're in your most fertile phase — but it does not guarantee pregnancy.