Most women rely on a thermometer to measure their fertility throughout the month. Their internal body temperature fluctuates with their ovulation cycle, so it increases when an egg is released and returns to normal levels after the cycle ends. The thermometer has proved a reliable method since at least the 1960s and '70s, albeit one that’s time-consuming and kind of annoying. Now, a new wearable called Ava wants to replace the decades-old technique. It claims to be the world’s first fertility wearable that helps women plan for conception, although it’s not for women who have infertility. It makes tracking a temperature reading easier, but more than anything else, it helps women plan ahead by prompting them to have sex while they’re ovulating.

The Ava claims to track more than just temperature. It measures resting heart rate, skin temperature, heart rate variability, sleep, breathing rate, movement, perfusion, bioimpedance (the resistance of body tissue to tiny electric voltages), and heat loss. Owen Davis, a doctor and professor of obstetrics and gynecology and reproductive medicine at Weill Cornell Medical College, told The Verge that beyond temperature readings, the other measures aren’t universally agreed upon as accurate indicators of ovulation. But with that being said, he also noted that it’s possible Ava’s algorithm can accurately determine when a woman can conceive.

To prove its accuracy, the wearable underwent a clinical trial during which it accurately identified five fertile days 89 percent of the time in 41 women. The study hasn’t been peer-reviewed or published yet, although Ava’s makers hope to have the results out by the end of the year.

Because Davis wasn’t able to read the study, he couldn’t make any conclusive statements about the device’s effectiveness. He did see its merits, though. If women can get an advanced heads up on when they’re going to ovulate, they’re more likely to be able to conceive. It might not be as accurate as LH-detecting test strips, which look for a hormone that’s only released in high quantities during ovulation, but Ava isn’t trying to replace hormone tests.

We still need to see the study

The only other thing to note is that the company behind Ava hails its FDA-approval, which while it’s not a bad thing to have, doesn’t lend much credibility. It only received Class One approval, which is the same qualification that dental floss holds. The FDA presumes wearables can’t cause much harm if they aren’t working properly, so it doesn’t as rigorously scrutinize them like it does with pharmaceuticals. Really, until we see the full study we can’t properly analyze the device, but for now, its claims don’t seem to be so preposterous.

The Ava is available now for $199.

Correction 8/1 8:39 AM ET: Corrected that a woman's temperature increases during ovulation, not decreases.