Notorious child deaths in New York often result in a sharp increase in the number of calls to child abuse hot lines. That is what happened in November 1995 after the death of 6-year-old Elisa Izquierdo, which prompted the city to create the Administration for Children’s Services.

For a year after Elisa was tortured and fatally beaten by her mother on the Lower East Side of Manhattan, reports citywide were up by roughly 12 percent, to an average of 4,500 calls a month.

But child welfare authorities say they are astounded by what has happened this year. After the highly publicized parental abuse and beating death of 7-year-old Nixzmary Brown in Brooklyn in January, complaints soared to record highs — nearly 8,000 in the first month — then leveled off at an average of 32 percent above 2005 figures. For October, the most recent month for which the city has data, there were roughly 6,000 reports of child abuse and neglect, up by 37 percent over last year.

There have been peaks and valleys in the numbers. But city officials say the high average rate of complaints is the result of several factors, most strikingly the improved coordination with schools to ensure that they report when children miss consecutive school days, as Nixzmary did.

The officials say this heightened awareness means cases are being caught early, preventing tragic outcomes. They liken it to the “broken windows” approach to fighting crime: stop criminals when they commit minor acts of vandalism, and they will never graduate to more serious offenses.

“What we learned from the Nixzmary case is that we want a system in place that produces a quick response to early signs that will prevent a situation from worsening,” said Deputy Mayor Linda I. Gibbs, who is leading a task force to coordinate efforts among city agencies in spotting abuse.

But advocates who say that more children should be kept with their parents see a dark side: more children in foster care for longer periods of time. Indeed, the number of children the city places into foster care is rising at a faster pace since Nixzmary’s death, up by about 55 percent over the first 10 months of last year, which amounts to 2,195 more children. That trend, however, masks a different, perhaps more significant fact: There were 16,256 New York City children in foster care over all at the end of July, the fewest in two decades.

After Elisa’s case, the number of children in foster care remained above 41,000. But there were few measurable improvements in their safety for several years.

“During periods of time of increased reporting and increasing placement we’ve seen increased fatalities,” said Michael Arsham, executive director of the Child Welfare Organizing Project.

Mr. Arsham worries that families with marginal problems will not seek basic services out of fear that child welfare authorities will be too willing to take children into foster care.

“Increased reporting strains relationships between families and their children’s schools and health care providers,” he said. “In effect it can drive families away from the services needed to keep their children safe.”

Child welfare officials say that removals to foster care as a percentage of complaints have risen only a bit — to 11.4 percent, up from 9.4 percent. They add that the cases that do lead to removal are serious. City officials note that while the rate of placement in foster care has increased, the total number of children in foster care has decreased as more families are kept together but with continual supervision by Family Court.

As for complaints, in the 10 years between the Elisa and Nixzmary cases there have been numerous fluctuations in numbers of hot line calls, sometimes propelled by high-profile abuse cases, sometimes for reasons that are unclear.

Yet officials have been surprised by the sustained level of calls since the death of Nixzmary.

One main reason, they believe, has been the much stricter enforcement of a 10-day rule for reporting educational neglect. If a child misses 10 consecutive days, his or her school is obligated to investigate. If school officials cannot find any reasonable cause, such as sickness, then the officials must call the case in to the state hot line for abuse.