Ohden also learned she is alive today because a nurse heard her weak cries, slight movements and gasps for breath as she lay discarded as medical waste and rushed her to intensive care.
And in a macabre twist, it emerged another nurse at the hospital had instructed the others to "leave the baby in the room to die".
Devastatingly, OHden, who lives in Missouri, US, found out that that woman - one of the supervisors in charge - was her grandmother.
Ohden has told her astonishing journey exclusively to Mail Online and reveals how she learned to forgive her mother and grandmother - whom she has chosen not to name.
The circumstances around Ohden's traumatic start in life took her decades to fully unravel.
Such a discovery would drive most people to become bitter and twisted. But OLhden - who was adopted by a loving family and reunited with her birth mother last year after a 17-year search - says she's found it in her heart to forgive.
"I discovered that my birth mother, aged 19, had been forced into the abortion by her own mother, who was an educational nurse at the hospital," said the 40-year-old from Kansas City, Missouri, who has written a memoir about her life.
"She was heavily sedated and didn't know that I had been born alive. It would be 30-odd years before she learned the truth.
"It's been a long and painful journey from shame and anger to faith and forgiveness. But I refuse to be poisoned by bitterness - that's no way to live."
Battle to live
The doctors who did the abortion at Saint Luke's Hospital in Sioux City, Iowa, had estimated that Ohden's mother was about 20 weeks along.
But the fact that she had survived the saline infusion - a method largely no longer used in the US and UK because of its failure rate - led them to believe she was actually 31 weeks when induced.
Melissa suffered jaundice, respiratory distress and seizures. It was expected that even if she did survive she would have vision problems, hearing loss and developmental delays.
Three weeks later, she was transferred to the University Hospital in Iowa City. The nurses who cared for the nameless baby made her tiny clothes and colourful booties.
One, called Mary, decided she needed an identity and named her Katie Rose.
At three months old she left hospital and was taken in by Linda and Ron Ohden, a couple who had already adopted a girl called Tammy, four years older than Melissa.
For years, her adoptive parents and Mary kept in touch, exchanging Christmas cards and letters with pictures and updates on her progress. When Ohden got older, she wrote the letters herself.
"Mary and I began a friendship that would last for decades," she explains. "It made me feel so special that this nurse cared for me when no one else did."
Despite early struggles, by age 5 Melissa had caught up developmentally and was given a clean bill of health.
The bombshell moment
Melissa and her sister had been told early on they were adopted by their parents, who had a natural son called Dustin when Melissa was 6, despite believing they couldn't conceive.
"Tammy and I fought like sisters typically do," said Ohden. "It was during one of these explosive arguments, when I was 14, that she blurted out, 'At least my parents wanted me!'.
"I ran to my adoptive parents who eventually told me the devastating truth - that I had survived a botched abortion. They had never intended for me to know.
"My world felt like it stopped spinning that night. I felt, angry, scared, ashamed and even guilty for being alive."
Ohden then spent much of her teenage years "in great emotional pain", developing bulimia and turning to sex and alcohol.
"I was drinking heavily to numb the pain. But my parents never realised how much I was hurting because I was so good at hiding it."
Desperate search for the truth
Ohden pulled herself together and headed off to the University of South Dakota to study political science.
She would later learn that her biological mother had attended there as well.
And astonishingly, her maternal grandmother - the very woman who orchestrated the abortion - was a professor at the university when Ohden was there.
"I didn't know this at the time of course, but I look back and wonder if we ever unwittingly crossed paths," said Ohden.
At 19, the desire to know more about her background ate away at her and she began her search to find her birth family.
"I couldn't put my finger on it but I knew then something sinister had gone on."
There was little information on her adoption papers, so their identities were a mystery.
Coincidentally, she soon ended up moving to Sioux City, where the failed abortion had taken place, which gave her the chance to search local records.
She pored over phonebooks, newspapers on microfiche, and year books at the library, not knowing her birth mother's name but looking for someone who looked like herself.
She also put an advert in the local newspaper appealing for anyone with information to come forward, but to no avail.
After years of futile hunting, Ohden came across a startling lead when she was 30.
"I knew my maternal grandparents' surname and where they had been employed, so that was a big piece of the puzzle," she said.
"I was flicking through a nursing college year book when I came across a woman I suspected was my grandmother. I still didn't know at this stage her full role in what happened."
She sent them a letter, but only her grandfather wrote back.
"He said my live birth was not the intention the day I was born. He also made it clear I wouldn't find my birth mother through them because they were estranged from her.
"It was evident their relationship with my mother was never the same after my birth. I couldn't put my finger on it but I knew then something sinister had gone on."
Finding her father
That same year, Melissa requested her medical records, which gave her a breakthrough - the hospital administrators had forgotten to black out her parents' names.
After discovering she was living in same city as her biological father, she wrote to him.
"I have every reason to believe he never knew I was born. I simply told him that I was alive, and that I wasn't angry or bitter. But he never responded."
Six months later she searched the internet for his name and discovered he had very
recently died when she came across his obituary. She then contacted his brother.
"His family were aware of my existence, they had come across my letter to him when they were clearing out his office after his death.
"They told me he once said 'I have done something I'm so ashamed of but I can never say what'.
"Knowing what I know now, I take that to mean that my mother was being forced to have an abortion and he did nothing to stop it.
"Perhaps he felt too much shame to respond to me, I will never really know."
Answers at last
Ohden gave up her hunt for a while. By then she was married to IT worker Ryan, now 42, with whom she has two daughters, Olivia, 9, and Ava, 3. Her oldest was born at the same hospital where she survived the abortion.
Then, when she was 36, her biological mother's cousin emailed her after learning she'd been in touch with the family.
She was told that her parents were college students - childhood sweethearts - who were engaged to be married when she was conceived.
"My mother was athletic and as a result had always had irregular periods, so she didn't realize she was pregnant until the third trimester," said Ohden.
"I was told she didn't want a termination, but my grandparents didn't approve of the relationship between her and my father.
"That was a huge shock, I'd spent so many years thinking my mother never wanted me.
"My grandmother arranged for the saline abortion within days of finding out about the pregnancy. My heart ached for my mother for having gone through that.
"I also discovered my mother's sister visited her in the hospital during the five-day infusion and tried to get her out of there, but the staff said it was too late."
Melissa wondered how she could be put up for adoption without her mother's consent, and came to the conclusion her signature must have been forged.
A nurse who worked at the hospital when she was born told her about the staff member who saved her - and her grandmother's disturbing attempts to deny her a chance of life.
"I have never met the woman who took me to neonatal but she's an angel, I owe her my life," said Ohden.
Emotional reunion
Finally, after Ohden had spent 17 years searching, the cousin put her in touch with her mother.
"I can't even remember now who emailed who first, but I recall we were both so shocked," she explained.
"My mother had no idea I was alive. Can you imagine? We chatted for three years before we met. I think we were both scared of rejection.
"Then I bit the bullet and suggested we meet. Her reply was enthusiastic.
"When we finally met in May last year, I could see her in the distance getting nearer and part of me wanted to run away. It was scary.
"Then we hugged and both cried. I said, 'It's been a long time'. She told me, 'I was robbed of you'. Then it felt really natural.
"She carries a lot of guilt and lives with many regrets but I told her I don't blame her at all.
"I have only forgiveness in my heart, for my father too and even for my grandmother."
Ohden found out that her grandmother had died some years earlier.
She also discovered she has two half-sisters, one of whom she has met and the other she plans to see soon. She has seen her mother a few times since and is in regular contact.
After a career in social work, Ohden is now a motivational speaker as well as an author, and she founded the Abortion Survivors Network to support others in the same position.
"I have been in touch with 223 abortion survivors, mainly from the US but from all over," she added. "It has devastated lives.
"Through my Catholic faith I have learned to forgive. It doesn't make what happened okay, but it releases you from the pain. We are all human and we all make mistakes."
You Carried Me: A Daughter's Memoir Priced is published by Plough Publishing House and is priced at $13.59
