Chen gave birth to their daughter more than two and a half years after her husband's death.
Many people saw Pei Xia Chen for the first time at one of her most difficult moments.
In December 2014, her husband, New York City police officer Wenjian Liu, and his partner Rafael Ramos were ambushed and killed in their patrol car.
At Liu's funeral the following January, the tearful widow spoke about her husband, her "best friend" and "hero" whose parents were "his everything."
"Even though he left us early, I believe he is still with us." Liu was 32.
On Tuesday, more than two and a half years after her husband's death, Chen gave birth to their daughter, Angelina, at New York-Presbyterian Hospital.
On the night her husband was shot, Chen asked that his semen be preserved with the hope of one day having their child, according to a New York City Police Department announcement that included a photo of the new mother and baby Angelina wearing a NYPD knit cap.
Liu's mother, Xiu Yan Li, said, "The past three years have been the most difficult. This is the best news we've gotten."
Chen, who goes by Sanny, said she felt early on that she would have a daughter.
"I told my friend, 'It's going to be a baby girl,' she said. "My friend said, 'No, you haven't even checked the sonograms,' but I was right!"
Chen had recently married Liu when he was fatally shot in Bedford-Stuyvesant by gunman Ismaaiyl Brinsley, who would soon take his own life.
Thousands came for funeral for Liu, believed to be the first Asian American police officer killed in the line of duty.
Speaking at the ceremony, Liu's father, Wei Tang Liu, talked about his son's dedication to his family.
"He called me every day before he finished work, to assure me that he is safe, and to tell me, 'Dad, I'm coming home today, you can stop worrying now.'"
Speaking in Chinese, he added, "Today is the saddest day of my life. My only son has left me."
Liu, whom many of his colleagues knew as Joe, had come to the United States with his parents from China when he was 12 in 1994.
On Tuesday, Liu's parents came to see Chen and the grandchild that once must have seemed inconceivable with the loss of their son.
Chen didn't tell her in-laws about her attempts at artificial insemination until she was pregnant.
"She didn't want to break her family's hearts if it wasn't successful," Susan Zhuang, a family friend, told Newsday.
"The parents were very emotional, crying and holding the baby," Chen's friend Maria Dziergowski told the New York Post.
Liu's mother told the New York Daily News that the baby "looks like my daughter-in-law. But this part, the eyes and the forehead, looks like my son. The top of the face looks like my son. The bottom looks like her mother. The head looks exactly like my son.
"I see my son in her."
She told Newsday that the family plans to take the baby to visit Liu's grave when she's a month old.
"This way I can tell him he has a daughter," she said.
Liu's father, speaking in Cantonese with PIX11, said "My heart is filled with love."
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(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)