It’s long been adored by celebrities – but prenatal yoga isn’t as harmless as Gwyneth Paltrow, Jessica Alba and Sienna Miller would have you believe.

A new case report reveals a possible danger for expectant mothers who choose to attend trendy yoga classes to keep fit and healthy.

A 35-year-old pregnant woman experienced a few weeks of vision loss – caused by straining as she stretched into a downward pose.

The difficult position, which sees a rush of blood to the head, was responsible for her valsalva retinopathy (VR), doctors claim.

They said the condition, which causes floaters in the eyes and temporarily affects vision, is usually associated with an episode of straining.

However, they warned the increased pressure in the form of practising the ancient Indian science could also trigger the bizarre symptoms.

A new case report reveals a possible danger for expectant mothers who choose to attend trendy yoga classes to keep fit and healthy

A new case report reveals a possible danger for expectant mothers who choose to attend trendy yoga classes to keep fit and healthy

Writing in the¬†BMJ Case Reports, doctors treating the patient, believed to be from Leicester, described it as an ‘unusual case’

They said: ‘We present an unusual case of VR in a pregnant woman after yoga. To our knowledge, it has not been reported in the literature in association with yoga.’

The doctors added that certain yoga exercises, such as pranayama – controlled breathing, have been linked to VR in medical literature.