One in three South Africans suffers from hypertension, something that medical practitioners call the silent killer.

Hypertension is known as the "silent killer" because, despite there being no signs or symptoms, it can lead to serious cardiovascular disease.

East London physician Dr Mzu Nodikida said as serious as hypertension in the general population is, it is worse in pregnant women.

"It is a non-communicable disease but chances of hypertension can be reduced by being active. It is considered to be idiopathic because it arises spontaneously and the cause is unknown," Nodikida said.

A blood pressure test is the only way to find out if your blood pressure is too high.

Professor Bryan Rayner, nephrologist and director of the Hypertension Institute at the University of Cape Town, said South Africa has seen an exponential growth in hypertension or high blood pressure (BP) over the last 20 years.

"In a sense we are facing a national health emergency, but because the links between high BP and death, heart disease and stroke are indirect, public awareness is poor.

"Risk factors for hypertension are a family history of hypertension, diabetes or stroke; obesity; African ethnicity; sedentary lifestyle; diabetes; high BP in pregnancy; and a poor diet with excess alcohol, sugar and salt," said Rayner.

"High BP generally causes no symptoms before it strikes unexpectedly.

"But the very good news is that medication, combined with a healthy lifestyle, can prevent complications."

Rayner added: "If your BP is greater than 140/90, further evaluation is required by a health professional. If your BP is between 130-140/80-90, implement lifestyle changes as you are at risk of hypertension."

May Measurement Month, spearheaded by the Southern African Hypertension Society, is promoting awareness and blood pressure screenings in several parts of the country.

In Eastern Cape, they will be at BT Ngebs Shopping Centre in Mthatha from May 19 to May 31.