A prosecutor's decision to charge a woman with manslaughter for the cocaine-induced death of her 2-day-old daughter could backfire and scare other pregnant drug abusers from seeking help, social workers say.

Some medical and legal professionals also disagree with Winnebago County State's Attorney Paul Logli's decision this week to charge Melanie Green, who became the second Rockford woman in a week to be taken to court for exposing an unborn child to cocaine."It could very well drive these cocaine-abusing mothers underground," said spokesman Dave Schneidman of the state Department of Children and Family Services.

"You want to develop an atmosphere where they know (they) can come into the health-care system and not be penalized. A punitive approach is not going to benefit the children," said Dr. Ira J. Chasnoff at Northwestern University Medical School, who has directed studies on the effects of prenatal cocaine use.

Early treatment for drug abuse works better, he said.

"The concern is that low-income women, who don't have access to educational and medical programs that middle-class women do . . . , might avoid the system altogether," said attorney Colleen Connell with the American Civil Liberties Union in Chicago.

The prosecutor defended his decision as a desire to protect children.

"The actions of this office reflect the concern, sometimes the outrage, of this community that children are born at risk, both at birth and for many years," Logli said in Rockford, 85 miles northwest of Chicago.

"The aim is to protect children."

Green's baby, Bianca, died Feb. 4. An autopsy said the infant died of oxygen deprivation linked to cocaine exposure late in the pregnancy.

Green, 24, also was charged with delivery of a controlled substance to a minor, Logli said.

Involuntary manslaughter is a felony punishable by two to five years in prison. The prosecutor said Green could face a 14-year maximum penalty if she is convicted of the drug charge. She was released on $3,500 bond. Arraignment is scheduled May 31, Logli said.

Schneidman said 90 percent of Illinois' cocaine babies are in Cook County - 1,095 of the 1,233 cases reported in 1988.

Infants exposed to cocaine tripled to 27 in Rockford during the past year, compared to the previous year, Logli said.

Prenatal exposure can cause numerous health problems including low birth weight, impaired motor ability, irritability that can hinder learning, strokes and seizures.

When a child dies after events that occurred "while the child was still in the womb, the law provides protection for that child and allows for prosecution of the person who causes those events," he said.

"My job as a prosecutor is simply to charge those events where violation of the law works toward the harm of others," Logli said.

Logli said he was unaware of any similiar deaths.

On May 1, a judge in Rockford convicted a juvenile mother of child abuse and neglect for cocaine exposure during pregnancy. The child, who shows no ill effects at 3 months, was removed from her custody.

A Florida woman was charged with child abuse and delivery of a drug in December after her child was born addicted to cocaine. Prosecutors said it was the first such case in that state.

In 1987, a California judge dismissed a charge of failure to provide medical care to a child, lodged against a woman whose son was born brain damaged and later died. Prosecutors accused her of ignoring a doctor's advice not to abuse drugs.