Hannah, 27, and Jenny, 37, allowed cameras into Winchester’s Mother and Baby Unit to follow their stories of admission, treatment and hopeful recovery.
Postpartum psychosis is a severe mental illness that can affect a woman after she has had a baby.
According to the NHS, it is thought to affect around one in every 1,000 women who give birth.
The condition causes women to experience hallucinations and delusional thinking. They are often overwhelmed and experience extreme low and high moods, paranoia and dangerous thoughts.
Specialist psychiatrist Dr Alain Gregoire, who features on the documentary, called it the "most severe illness" he has come across in psychiatry, but explained it's also something women can recover from relatively quickly.
Three months after giving birth to her first daughter Esther, Hannah, who is a trained nurse, was admitted to the psychiatric unit in Winchester.
She had started to experience illusions and suicidal thoughts. On one afternoon at her parents home she collapsed into a foetal position and wouldn't stop screaming.
Her husband, Andy, said he didn't recognise her and nothing he said could comfort her.
Hannah was sectioned because Dr Gregoire said there was "no other way" to ensure she got the help she needed.
"I don't think I've seen anybody as sick as that," said Hannah's mum Pippa. "I couldn't explain what had happened to my own daughter.
"It was horrific. I didn't expect that at all."
Hannah received specialist psychiatric care and round-the-clock support with her daughter, Esther, who stayed with her in hospital.
"I kept thinking I was going to hurt Esther," said Hannah. "Not deliberately, but because I felt so weak and so anxious.
"I was worried I would forget something and when I said I was worried about hurting her to other people, they thought I meant physically."
The new mum is now on medication, as well as undergoing a range of therapy treatments.
As Hannah's condition improved, she was allowed to spend time away from the unit at home with her husband - but during this time, she began to deteriorate.
The programme also followed Jenny, who gave birth to her second child Libby in January 2016. She has been with her husband Henry since she was 22.
Jenny was diagnosed with bipolar disorder and severe depression six years ago. Because of this, she had to give up her career as an attorney and has since been working as an artist.
For Jenny, having bipolar disorder meant she knew she had a 50/50 chance of becoming ill after having a baby.
When her first child, Reuben, was born she showed signs of being unwell but with psychiatric support at home and medication, she got better. Reuben now lives at home with her husband.
However, three weeks after her second child Libby was born, Jenny noticed early warning signs of psychosis and asked to be admitted to Winchester's Mother and Baby Unit.
Dr Gregoire described her mood as "elevated" and said she is constantly high and quite irritable at times.
"It's not right to assume just because somebody is high, like Jenny, that it is a wonderful, pleasant and great experience," he explained.
Jenny described the illness as "her mind and thoughts going really fast, but people aren't able to keep up".
"I often think of it as being a state of my mind in overdrive," she explained. "Like having many more thoughts than you normally do all happen at the same time."
One thing Jenny finds hard is the intense programme of medication, but as her condition is deteriorating her medication has had to be increased.
Dr Gregoire said Jenny's condition was getting to a level of severity where she was acting on fears and thoughts. At one stage, she put Libby in the bath because she thought it would be a good place to keep her safe from a fire.
As her condition worsened, Jenny had to be separated from her daughter and put in a high-risk hospital.
The documentary follows the two mothers as they are admitted into the unit right through to their steps to recovery.