When Withings introduced pulse wave velocity (PWV) measurements on its flagship scale, it offered customers an indicator of their cardiovascular health. In addition to more standard calculations, like weight and body mass index, the Body Cardio scale used the PWV measurement to estimate the "stiffness" of users' arteries and the correlated risk of hypertension or cardiovascular incident. But in January 2018, Nokia (which then owned the company) voluntarily pulled the feature, fearing that it might need additional regulatory approval. As of today, Withings has returned the PWV measurement to its scales in Europe.
Withings restored the feature via an over-the-air-update, so existing EU customers can now see PWV measurements on their scales. Regulators assured the company that no further approval is required in the European Union. Withings is still in talks with regulators in the US, so customers in the states will have to hold out a little longer.
PWV essentially measures the speed at which your blood circulates. A fast reading indicates "stiff" arteries and poor cardiovascular health, and a slower rate generally suggests more flexible arteries and good health. It's similar to blood velocity measurements normally taken by a cardiologist using a medical device called a sphygmometer. It's likely that, in 2018, Nokia feared the scale might need regulatory approval on par with other medical devices. While we now know where the EU stands on the matter, we'll have to wait to see how much regulation the US deems necessary.