Despite the trauma of this, and a previous miscarriage last year, the 40-year-old actress and TV presenter is adamant she will still have more children with husband, music producer Chris Hughes.
Amanda, mum to five-year-old Lexi, said: "I am an optimist. I think, as bad as life sometimes gets, there is so much joy and so much good stuff that there is a balance. Although what happened is obviously horrifying, we can go on to have more children."
She had been due to give birth in late March but in early February, during filming of Britain's Got Talent, she became aware that the baby had not moved for 24 hours. She went into the West Middlesex hospital where she gave birth to a stillborn son.
"I met the three midwives who looked after me through a documentary I made two years ago at the hospital and they are fantastic," she said in You magazine. "They have gone on to become personal friends and they got Chris and me through the worst time of our lives.
"They went above and beyond the call of duty, both personally and professionally. I cannot thank them enough."
Amanda also explained how the experience has brought her even closer to Chris, who she descibes as her 'rock'.
"We argue and bicker like all couples, and Chris calls me The Lip because he thinks I talk too much. But he is the love of my life and I am his and – how lucky – he is also my best friend, which is why we can get through anything. We are polar opposites. He is very private, very closed, and I am pretty much an open book, but together it works. I always think we are like the plus and minus signs on a battery. It wouldn't work without one or the other of us." she says.
She explains that she and Lexi have a catch phrase: "Never give up". "I say, 'Never give up, Lexi', and she says, 'Never give up, Mama'.
Amanda, who plays Fiona in Shrek the Musical, is back on Britain's Got Talent tonight, alongside Simon Cowell, the man she calls 'my other favourite ogre'.
More on Parentdish: Late miscarriage: Should I be worried?