Do Saliva-Based Ovulation Predictor Kits Really Work?

When you're trying to conceive, accurately pinpointing your most fertile days is vital. You can use a urine-based ovulation testing kit to help you with this task, but let's face it, not every woman likes peeing on a stick. And that's where saliva-based ovulation tests come in.

Just prior to ovulation, estrogen levels increase and create a distinct pattern in dried mouth saliva that looks like frost on a window pane when viewed under a microscope. Because of its distinctive shape, the pattern is called ferning.

Unlike traditional fertility predictor kits that use urine to test for an increase in luteinizing hormone, which typically spikes one or two days before ovulation, saliva tests come shaped like a lipstick tube, and actually contain a small microscope. To use, you simply deposit a small saliva sample on the surface of the lens, allow it to dry, and then look through the microscope to check for ferning.

Makers of saliva tests available in the US say that, when used properly, ovulation prediction results are about 98 percent accurate. But as a new microscope saliva test hit shelves in the UK, fertility experts there are warning that saliva tests have a history of being unreliable, including turning up fern patterns in populations that don't ovulate.

According to one fertility specialist interviewed by the UK's Daily Mail, "A study of saliva testing devices...found that 8 out of 10 post-menopausal women and all 10 men tested positive for ovulation! In this same study, researchers concluded "that the saliva test is unreliable for predicting the fertile time and its use should be discouraged," the expert reports.

In the US, where saliva tests have been available for the past few years, the Food & Drug Administration (FDA) agrees that at-home saliva kits aren't always reliable. Problems with obtaining accurate results seem to arise because ferning can be disrupted for a number of reasons, including smoking, eating, drinking, and teeth brushing before testing, and improperly putting saliva on the slide.

On the other hand, the FDA says ovulation tests that use urine samples (aka pee-on-a-stick) can detect luteinizing hormone reliably about 9 times out of 10, as long as test directions are followed.