In a statement released, Apple said hypertension notifications on Apple Watch use data from the optical heart sensor to analyse how a user’s blood vessels respond to the beats of the heart.

The algorithm works passively in the background, reviewing data over 30-day periods, and will notify users if it detects consistent signs of hypertension.

"These notifications provide users with valuable insights into their health as it relates to this widespread condition simply by wearing their Apple Watch, so they can begin making potentially lifesaving behavioural changes, or start treatment to reduce their risk of serious, long-term health events," the tech major said.

Like all of Apple’s health features, the company said its hypertension notifications are grounded in rigorous scientific validation.

The feature was developed with advanced machine learning and training data from multiple studies totalling over 100,000 participants.

Its performance was then validated in a clinical study of over 2,000 participants.

While hypertension notifications will not detect all instances of hypertension, with the reach of Apple Watch, the feature is expected to notify over 1 million people with undiagnosed hypertension within the first year.

“Hypertension is one of the most widespread yet under-diagnosed health conditions. Integrating opportunistic detection into a device people already wear daily will democratise access for early detection and help people have more informed conversations with their doctors,” says professor Dorairaj Prabhakaran, the Centre for Chronic Disease Control’s executive director and the World Heart Federation’s president-elect.