According to Kuo, the Apple Watch Series 4 will have upgraded health-tracking sensors.
As of now, it's not clear exactly what type of sensors will be included, but Apple has hinted in the past that it would like to add more health-monitoring features to the Apple Watch.
Last September, the company announced it partnered with Stanford University for a program called the Apple Heart study, which would monitor Apple Watch users for irregularities in their heart rates that could be symptoms of a heart condition.
And last December, Bloomberg reported that Apple was working on new technology for the Apple Watch that would let the device monitor a wearer's heart similar to a clinical-grade electrocardiogram.
There have also been reports that Apple is working on a noninvasive glucose monitor for the watch, but that technology is likely years away, according to a report from The New York Times.
Adding highly advanced sensors to the watch would likely require FDA approval. Apple CEO Tim Cook has specifically said in the past that he doesn't want "to put the watch through the Food and Drug Administration (FDA) process."