Ann Pettway, who pleaded guilty in February to one count of kidnapping, expressed remorse in a brief statement to the federal court in Manhattan.
"I would like to apologize to the family," Pettway told U.S. District Judge Kevin Castel.
"I am deeply sorry for what I've done. If they don't accept it, it's understandable," said Pettway, adding, "I'm here today to right my wrong and ask for forgiveness."
According to prosecutors, the parents of the baby girl, named Carlina Renae White, had taken her to Harlem Hospital on August 4, 1987, because she had a fever. Early the following day, hospital personnel discovered the baby was gone.
For 23 years Pettway raised the girl under another name and as her own child, prosecutors said.
In January 2010, when the victim sought to get prenatal care during her own pregnancy, she had difficulty getting a birth certificate from Pettway, prosecutors said. The victim became suspicious and contacted the National Center for Missing and Exploited Children. DNA confirmed she was Carlina White, the daughter of Carl Tyson and Joy White.
Pettway turned herself into the FBI in Bridgeport, Connecticut, shortly after the victim, now in her mid-20s, was reunited with her birth parents. Pettway, now 50, told authorities she took the baby because she had suffered two stillborn births, one just months before the abduction.
The birth parents both read statements Monday during Pettway's sentencing hearing.
"I never had a chance to put my daughter on a school bus," said Carl Tyson, making direct eye contact with Pettway. "What they should give you is 23 years for what you took from me."
A teary-eyed Joy White told a packed courtroom, "I only spent 19 days with (her daughter) from birth, and those were the most memorable days of my life."
Both parents admit to difficulties trying to get to know their now-adult daughter.
Judge Castel recommended Pettway serve her sentence in facilities in Danbury, Connecticut, or Tallahassee, Florida, where she could participate in mental health programs.
In addition to 12 years in prison, Pettway was also sentenced to 3 years probation and a $100 special assessment fee.