Gemma, 35, recalled the heartbreaking experience she went through four years ago in 2012, and revealed details of the traumatic birth on Channel 5 show In Therapy.
Speaking to therapist Mandy Saligari, the star opened up about how she hadn't known she was pregnant, and the moment she began to realise something was wrong.
'I woke up with excruciating pains. My mum was like, "You've got a bad stomach", and I'm thinking, "Nah, something's not right here".
'I rang an ambulance. I ended up giving birth on my landing to this four and half month baby.
'The next minute they put me in the ambulance and this woman is going to me, "Do you want to bury your baby? Do you want to sign it over for scientific research?"'
Gemma on Loose Women earlier this year
Gemma recalled how her mum wept at the birth, but that the reality star felt she had to attend an awards event as though nothing had happened. 'My mum started crying, but I knew I had to go and perform at the National Television Awards.
'I had loads of padding on because I was bleeding heavily, but to the outside world they wouldn't know.'
This isn't the first time the former Big Brother favourite has spoken about her miscarriage. Gemma previously revealed that she didn't tell her friends about it at the time, and that she thought it was a punishment for previously having an abortion after falling pregnant - which caused her to overeat.
'I felt guilty. I used to feel so empty. I had this terrible feeling inside me and the more I ate, the more it went away.'
Gemma with her mum, Joan
Channel 5's In Therapy has also featured celebrities including Katie Price, who opened up during last year's series about fame, motherhood and her relationships. This series also sees former EastEnders star Danniella Westbrook taking part in the show.