Louis Theroux will explore post-natal mental illness in an upcoming documentary for BBC Two.

The filmmaker will spend time in two specialist psychiatric units which treat mothers experiencing serious mental illness while allowing them to live alongside their babies for the documentary which is titled Mothers On The Edge.

He meets women who have been admitted with a range of conditions, including depression, anxiety and psychosis, often triggered by birth or the strains of motherhood.

Theroux said of the documentary: "Postpartum mental illness, like many aspects of mental health, is all too common and not acknowledged enough.

"We as a society do so much to celebrate new motherhood and to romanticise the relationship between new mothers and their babies, for understandable reasons.

"But the sad fact is, for many mums, their experience of having a baby is traumatic and they don't experience Hallmark Card feelings of love."

The British documentary filmmaker said the women featured "took a huge leap of faith" in opening up and speaking to him.

"They bared a great deal of their souls and risked the judgment of less understanding elements of society," he said.

"Their bravery and candour is awe inspiring, and it was a privilege to be invited into their families during a most vulnerable period in their lives."

He said he hopes the film helps to "normalise postpartum mental illness and stimulate a discussion on how we can best care for mothers at the time they need it the most".

Mothers On The Edge will air on BBC Two in May.