“There’s a sacredness about the role of mother,” he said. “When a woman is not fulfilling her role, it shocks the conscience, more than if she commits a crime. If she was prostituting herself or dealing drugs or stealing to feed, clothe and shelter her children, people would be more sympathetic.”

Details of Ms. Santiago’s troubled past  her learning disabilities, her abusive relationships and her miscarriage shortly before Nixzmary died  have caused some who followed the trial to wonder about her capacity to help her daughter.

Awilda Cordero, a victims’ rights advocate, said that Ms. Santiago herself had been abused by Mr. Rodriguez and feared him. “She didn’t know how to protect this child,” she added.

Katherine M. Franke, the director of Columbia Law School’s Program in Gender and Sexuality Law, said Ms. Santiago’s sentence reinforced simple notions of parental roles, with men perceived as more violent and women as saddled with “all the obligations and responsibility  and ultimately the punishment  for what happens to their children.”

Hedda Nussbaum knows the feeling of being vilified by the public for perceived failings as a mother. In 1987, Ms. Nussbaum and her companion, Joel B. Steinberg, were arrested after the 6-year-old child they were raising, Lisa Steinberg, was taken to a hospital unconscious after Mr. Steinberg struck her. A few days later, Lisa died. Ms. Nussbaum, who also was abused by Mr. Steinberg, testified against him at trial, and he was convicted of manslaughter.

Even as the public saw the evidence that Ms. Nussbaum was abused  her beaten face became a symbol of battered women  some people continued to blame her for Lisa’s death.

In a telephone interview on Friday, Ms. Nussbaum, who now works to help victims of domestic violence, said that Ms. Santiago’s longer sentence might have stemmed from prejudices similar to those she faced. “People are always blaming the mother,” she said. “In these cases, all things are not equal. If he struck the blows, she should not spend more time in prison.”