Editor's Note: This is part three of a three-part series from our partners at Reuters.

BROOKSVILLE, Florida — Jennifer Lacey Frazier recently completed drug treatment and parenting classes. The help came too late to save her daughter, Jacey.

In December 2011, Frazier gave birth to Jacey at a hospital in Charlotte, North Carolina. The baby inherited her mother’s blue eyes — and Frazier’s dependency on drugs.

Jacey spent two weeks suffering through withdrawal, a result of the methadone Frazier took during pregnancy to control an addiction to prescription painkillers.

Federal law calls on states to require hospitals to report newborns hooked on drugs to child protection services. Records show the North Carolina hospital did precisely that. It alerted child welfare authorities just across the border in nearby York County, South Carolina, where Frazier had been living with her mother.

But the 2003 law has a second, distinct provision — one that many states have failed to embrace, putting thousands of newborns in jeopardy each year, a Reuters investigation has found.

Related: New Help for Babies in Withdrawal and Moms Battling Drug Addiction

That provision calls on state child protection authorities to immediately assess all cases of drug-dependent newborns. Social workers are then supposed to develop “a plan of safe care” for every infant who is either “affected by illegal substance abuse” or experiencing symptoms of drug withdrawal.

York County took no such action, documents and interviews show. Instead, a hospital social worker wrote in Frazier’s medical records that the county child protection agency “will not be following up with infant.”

The reason: South Carolina has a state law that conflicts with the federal provisions. It says that child protection authorities don’t have to investigate cases of drug-dependent newborns if their mothers were using drugs prescribed by a doctor. Frazier had a prescription for methadone.

Six months later, after Frazier moved to Florida with her daughter and Jacey’s father, the girl was dead — the victim of a lethal dose of methadone Frazier mistakenly gave her.

Click Here to Read the Reuters Series on Drugs and Newborns

“I wish social services had been at my home investigating, talking to me, checking on Jacey,” Frazier wrote to Reuters last month in a letter from prison. “I didn’t just slip through the cracks in the system; I fell through the canyon into hell.”

Reuters identified 110 cases since 2010 in which children died preventable deaths after being sent home from the hospital to families ill-equipped to keep them safe. In each of those cases, Reuters found evidence of a mother’s use of opioid drugs during her pregnancy.

In some instances, hospitals failed to alert authorities to infants born dependent on drugs, despite a federal law that was intended to ensure each such case be reported to child welfare workers.

Social service agencies are falling short, too. Of the 110 deaths Reuters uncovered, 74 other cases appear similar to Jacey’s: Child protection authorities were alerted by the hospital to a drug-dependent newborn, but social workers either chose not to pursue the case or failed to adequately respond.

Related: Addicted Newborns: 'That Baby Is In Serious Danger'

In many of the fatal cases identified by Reuters, child protection workers conducted cursory investigations, or none at all. Sometimes, authorities created safety plans, but parents simply ignored them. In other instances, such as Jacey’s case, social workers followed less stringent state policies, which don’t require intervention if mothers are using drugs that are prescribed, typically to treat addictions.

“The fact that the mother is in treatment is a good thing,” said former U.S. Representative Jim Greenwood, a Republican from Pennsylvania who championed the 2003 federal law. “But that doesn’t prove that she has a place to live that’s safe. It doesn’t prove that she knows how to parent. It doesn’t prove that there isn’t a violent, other drug user in the home. It doesn’t say anything about the baby’s situation. And this is all about protecting the baby.”

The cases exemplify the wide disparities in oversight afforded to drug-exposed children across America, levels of vigilance that vary dramatically among the 50 states and even within the states themselves.

“In some areas, we had babies positive for marijuana removed from home, and in other places, kids tested positive for methamphetamine and they weren’t removed,” said Lisa Smith, director of the Oklahoma Commission on Children and Youth. “Depends on what part of the state you’re in.”

'A Pickup Load of Dead Babies'

Reuters found dozens of situations in which infants were released from hospitals into unsafe homes where family members used heroin, methadone or prescription painkillers, according to records from social workers, coroners and police.

Some of the newborns died at the hands of drug-abusing parents, even though hospitals had alerted child protection agencies.

One of the most disturbing deaths took place in Oklahoma. On Nov. 4, 2010, Maggie May Trammel died when she was just 10 days old. Mother Lyndsey Fiddler, high on a variety of drugs including opioids, accidentally put her baby in a washing machine with a load of laundry. Then Fiddler passed out.

Maggie May was found dead “after the wash cycle was completed,” a state review of her death shows.

Fiddler is now serving a 15-year sentence for manslaughter and child neglect.

“If only we could have gotten the baby somewhere safe when it was first born,” said Kevin Ickleberry, the police detective who arrested Fiddler.

Before Maggie May died, the Washington County office of the state Department of Human Services had received five reports about Fiddler. Each alleged neglect or abuse related to drug use. One of those reports came the day Maggie May was born.

But child welfare workers concluded Maggie May and two older siblings were safe and that Fiddler “was willing to work on parenting services,” a state report said.

The case sparked outrage and efforts by the Oklahoma to improve its child protection system.

The Oklahoma Commission on Children and Youth, an independent oversight agency, began reviewing why the state’s social service system was failing.

The commission examined 10 cases in which babies had been reported to child welfare authorities for exposure to drugs in families with a history of neglect or abuse. Only five of the cases had been investigated. Two were quickly dismissed by a child-abuse hotline worker as not appropriate for protection services. In three of the cases, parenting classes were recommended.

Eight of the 10 babies later died of neglect or abuse “on average within 6.5 months of their birth,” the commission concluded. Contributing factors, the panel said, were lack of treatment for mothers and inconsistent reporting by hospitals.

At one meeting, the commission’s chairman at the time, Bart Bouse, asked the state social services chief: “Does it take a pickup load of dead babies before we decide to act?”

In 2012, the state legislature passed a law requiring authorities to investigate any case in which a “drug-endangered” child is reported to the Department of Human Services.

A second panel of experts reported in 2013 that too many newborns and drug-using mothers were sent home together without safety monitoring. “Sometimes there was a tendency to ignore drug abuse in the home because the ‘medications were prescribed,’” the report said.

Today, Oklahoma has a protocol based on the 2003 federal law.

“We’ve made great strides,” said commission director Smith, but “there’s still a lot of work to be done.”

Amanda McKenzie with Liam. In a letter from prison, McKenzie accepts blame for the drowning death of her son. Reuters

'10 Times Stronger Than Any Pill'

Some of the cases Reuters examined show the challenges social workers face even as they try to do right by the child. Although each of the 110 deaths that the news agency identified was preventable, even some of the mothers who killed their children say social workers were vigilant.

“I’m not sure that anyone could have helped prevent my son Liam’s tragic death,” his mother, Amanda McKenzie, wrote last month in a letter she sent Reuters from prison. Her son drowned when McKenzie fell asleep with him in the bathtub.

When Liam McKenzie was born in March 2013, the hospital alerted social workers in Newport, Kentucky, about his mother’s extensive drug use. But neither Liam nor McKenzie tested positive for drugs, state records show, and the case was quickly closed.

About four months later, social service workers logged another report — from whom is unclear — alleging that baby Liam was in danger because his mother was using heroin.

Social service workers went to McKenzie’s house four times in a week before they found her at home on Aug. 2, 2013. In a report, they wrote that the home was “clean and free of clutter” and that mother and child had “formed a positive bond with one another.” But they told McKenzie that, because of the allegations, they were putting in place a “safety plan” that included random drug screenings. Later that day, McKenzie submitted to a drug test; it came back clean.

In the next two weeks, child protection records show, social workers attempted to reach McKenzie and couldn’t. They left voicemails and told her she needed to be drug tested again. There is no record that McKenzie responded. Social workers twice visited her house but got no answer.

Eight days after their last attempt to visit, baby Liam drowned when McKenzie fell asleep in the bathtub with him.

In an interview with Reuters, McKenzie said she had been taking prescription methadone, an opioid used to treat addiction, at the time of Liam’s death. She said she started using it because she had recently relapsed and wanted to stop snorting heroin and abusing painkillers. But the methadone, she said, was more powerful than she expected.

“It’s 10 times stronger than any pill I ever took,” McKenzie said.

Today, McKenzie is serving a five-year prison sentence after pleading guilty to reckless homicide.

Wanted Help

Jennifer Frazier, now 32, told authorities she confused the antibiotics she was giving to newborn daughter Jacey with the methadone Frazier was taking to kick an addiction to painkillers. A pre-sentence report found that Frazier was “extremely remorseful” and that the mix-up in medications was “not intentional.”

Even so, Frazier was sentenced to 15 years in prison in 2013 after pleading guilty to aggravated manslaughter of a child.

In a prison interview, Frazier admitted that, at the time, she was glad that she didn’t have to deal with child protection authorities. “That would be one more thing on my plate,” she said.

Since entering prison, she has taken parenting classes and has gone through drug treatment. If she had been forced to take those classes earlier — and if the state had threatened to take Jacey away — it might have saved her daughter’s life, she said.

Authorities never intervened, and more than 1,400 pages of hospital records reviewed by Reuters show why: Under South Carolina state law, authorities were not obligated to investigate further because Frazier was on prescribed medication, not illicit drugs.

Although the difference in the type of drugs Frazier was taking proved central in how social services handled the referral, the federal law makes no such distinction between illicit and prescribed drugs. It requires safety plans for all newborns with symptoms of drug withdrawal. These plans can include home nursing, substance-abuse counseling, housing and employment help, and a threat to remove the child if the parents don’t follow the guidelines.

Medical records show that Frazier provided a sanitized version of her drug history to the hospital. She claimed that she became addicted to pain pills after a car accident more than a year before Jacey was born. She told nurses that, six weeks before giving birth to Jacey, she switched to the prescribed methadone on her doctor’s advice because it was safer for the baby.

Records from the methadone clinic, however, show Frazier had been battling addiction much longer than she let on.

According to those records, Frazier, then 28 years old, had used cocaine since she was 14, crystal methamphetamine from ages 16 to 19, cocaine and crack from age 24, and the powerful painkiller Percocet since a back injury in the car accident. That accident had taken place and the addiction had started at least six years earlier — not one, as she had told the hospital. She admitted to that clinic she had been a frequent customer at “pill mills.”

There is no indication in hospital records that doctors, nurses or state social workers ever looked closely at Frazier’s background of drug use before letting her take Jacey home.

In one notation, hospital social worker Catherine Hall wrote that the county’s child protection service wouldn’t stand in the way of Jacey’s discharge from the hospital if the newborn were healthy enough in a few days. York County’s Department of Social Services, Hall wrote, “can follow up with infant and mother at their home if needed.”

Social services declined to open an investigation because of Frazier’s valid methadone prescription, hospital documents show. Frazier and Jacey later moved to Florida.

Reached by Reuters, Hall declined to comment. The county’s social worker, Becky Mann, referred questions to the South Carolina Department of Social Services. Department spokeswoman Karen Wingo said that unless there were other signs of abuse or neglect, the state would not typically accept a case if the baby’s drug exposure was from “medical treatment for the mother.”

Jennifer Frazier with Jacey. via Reuters

'There Was A Need'

Several times during her hospital stay, the records show, Frazier herself raised the issue of “dealing with infant withdrawal.” For almost two weeks, Jacey had been given smaller and smaller doses of morphine to help ease her shaking, clenching, wailing and other symptoms of opioid withdrawal.

Hospital records included this notation: “Home Health RN visits will begin after discharge.” They didn’t, Frazier said.

On New Year’s Eve 2011, the hospital determined that Jacey –- now 25 days old –- was well enough to leave. The discharge note also said Frazier was going to be referred to a service program called BabyNet. That never happened, Frazier said.

“They sent her home, and that was basically it,” she said.

Citing patient privacy, a spokesman for Carolinas HealthCare System, where Frazier gave birth, and a spokesman for BabyNet declined to comment.

Frazier takes responsibility for Jacey’s death — “I messed up,” she said. Only later, she said, did she realize just how much help she needed.

“If I was that social worker, I’d be knocking the door down, because I see what can happen,” Frazier said. “They need to find us, and they need to help.”

Additional reporting by John Shiffman