She has been haunted by thoughts about her birth parents since being adopted by an American family at the age of six.
On the first day in her new home, she was badly beaten for getting the wall dirty and made to eat alone in the kitchen.
"Whenever I felt down, I would wish my birth mother was next to me," the 53-year-old recalls.
She moved out of her adoptive parents' home to fend for herself at the age of 15.
When she turned 18 she went to the Catholic church that supported her adoption to find old documents about herself.
They indicated that she had been left outside a building on Gia Long Street (now Ly Tu Trong Street) in HCMC. A nun took her under her care and delivered her to the Hoa Binh - Gia Dinh Orphanage in the Go Vap District area.
She was airlifted from Vietnam on April 15, 1975, under Operation Babylift.
Hong, who lives in Burlington, Vermont, says: "In my dream, my mother raised me until I was three years old and left me at a well-known orphanage so that I would have a chance to get to America."
She had no birth certificate or knowledge of her biological parents.
In her twenties she found love and settled down with her husband, with whom she had three children. It was always on her mind, though, to track down her biological parents.
Quoc Chau, Hong's husband, says: "She had my and my kids' full support in finding her parents. However, there was not much we could do since we did not have much to go by."
After living abroad for more than four decades, Hong finally returned to Vietnam for the first time in 2016. Despite having only a fragmented and hazy recollection of her hometown, she felt an overwhelming sense of comfort as she stepped down from the plane.
But when she went the orphanage, she found that the person who had signed the papers allowing her to travel to the U.S. had died.
All the occupants of the apartment she had lived in had moved out by 1975.
Later she discovered she had an American father after submitting a DNA sample to the genealogy company Ancester.com in 2018.
"I set out to locate my mother but wound up locating my father instead," she says.
Nguyen Thi Thanh Hong (C) with her father and stepbrother at a family reunion in Oregon, the U.S., in 2019. Photo courtesy of Hong |
Her American father, who served in the Vietnam War in 1967-68, dated a new woman every weekend, and so never knew her biological mother.
"I was obviously not born on November 30, 1969, as stated in the official documents, given the length of time my father spent in Vietnam. From what my dad told me, I was born in 1968."
She keeps scouting through genealogy companies and online groups in search of details about her mother.
Earlier this year she shared her story on YouTube, and within half a day a family in the southern Dong Nai Province contacted her.
There was a strong resemblance between Hong and a woman named Van Thi Hue, 85, when their photos were compared.
That family has in fact been searching for a long-lost child named Hong for many years.
They communicated for a few days before Hong sent her hair and nails to Vietnam for DNA analysis.
She had a hard time sleeping as she waited for the results, and then her hopes were dashed as it was not a match.
"It was a bittersweet experience. I wished them all the best in finding their real missing relative.
"I hope one day all Vietnamese mothers who sent their kids to orphanages will upload their DNA on genealogy sites.
"This will help not only me but many other adopted children find their missing parents."
But she has no intention of giving up yet and has been sharing her story on various Vietnamese information groups and channels.
Her wish to reunite with her mother has only become stronger after she located her father. Though they live 3,000 miles (over 5,000 kilometers) apart, she still makes frequent trips to see him.
According to his two sons, their father rarely smiles except when Hong is around.
Hong says she harbors no resentment toward her mother for abandoning her, and all she has ever wanted was to find her and take her to live with her in America.
"From the time I was a child, I have wanted to find my mother. It was not uncommon for me to cry myself to sleep thinking about her.
"As I become older, my desire to find her only grows. The Asian ancestry in my veins is a mystery that keeps me curious as I get older.
"My heart has been broken for a very long time. Tracking down my father has only satisfied me to a certain extent. The void in my heart will be filled the moment I finally locate my mother."