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Why infants still die from SIDS

  • Story Highlights
  • Fewer than 2,500 infant deaths this year will be classified as SIDS
  • SIDS may be underreported because causes of infant deaths are mislabeled
  • Researchers investigate brain-stem problems and undiagnosed genetic anomalies
  • Babies who begin daycare before 4 months of age may be at increased risk
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By Margaret Renkl
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When Melissa and Rudy Haberzettl's son Jacob was born in November 2006, he was perfect in every way -- full-term, healthy weight, and a champion eater. Like many new moms, Melissa was determined to follow doctor's orders: She breastfed Jake exclusively, put him to sleep on his back, never exposed him to cigarette smoke, and kept soft toys and bedding out of his crib. And Jake thrived. "He was such a happy baby, always looking around and cooing," remembers the Colorado Springs, Colorado, mom.

Melissa and Rudy Haberzettl lost their son Jacob to Sudden Infant Death Syndrome.

Of course Melissa had heard about sudden infant death syndrome (SIDS) -- the designation most commonly used when a healthy baby dies in his sleep, suddenly and without any medical explanation -- but she wasn't really worried about it. "When you do everything right, you just don't think it can happen to you," she says.

But when Jake was 3 months old, the unthinkable happened.

Melissa had arranged to return to work two days a week as a physical therapist, and she had chosen an in-home day-care center highly recommended by friends. Though she felt anguished about leaving her baby for the first time, she also felt certain Jake was in good hands, and she resisted the impulse to check in. Rudy, also a physical therapist, didn't. He called the sitter three times, reporting to Melissa each time that the baby was just fine. He planned to pick up Jake at 3:30 p.m. Melissa hadn't heard from Rudy by 4 p.m., so she called his cell.

The instant she heard Rudy's voice, she knew something was wrong. "I could tell he'd been crying, and my husband does not cry." When Melissa asked, "Is Jake OK?" Rudy just said, "Stay where you are. I'm coming to get you."

Trying not to panic, Melissa called the sitter, but the person who answered would tell her only that the sitter wasn't available. By the time her husband arrived in a police cruiser a few minutes later, Melissa understood. "Jake's dead," she said as soon as Rudy stepped out of the car. "When he said yes, I just fell apart."

Why isn't SIDS solved?

The death of a healthy baby is always a terrible shock, but it may be even more shocking today. That's partly because SIDS, which is classified as a natural cause of death, is considered so rare. The official rate from the National Centers for Health Statistics is roughly one death for every 2,000 live births -- or .05 percent. The other reason? Many parents believe that the only babies still dying of SIDS are the ones whose caregivers just aren't following the safe-sleep rules. It's hard to blame them, given that the American Academy of Pediatrics's Back to Sleep campaign, which launched in 1994, has been credited with cutting the SIDS rate in half. Keeping your baby safe from SIDS

But as the Haberzettls learned so tragically, SIDS is still very much a threat, despite the accomplishments of Back to Sleep. And research suggests that the real SIDS rate may in fact be significantly higher than the official numbers indicate: Although fewer than 2,500 infant deaths this year will be classified as SIDS, an additional 2,000 seemingly healthy babies under 12 months will also die mysteriously in their sleep, according to the Centers for Disease Control and Prevention. SIDS may be a very rare event, but the news is terrifying nonetheless. No parent wants to consider the possibility of losing a child, which is why we've reached out to top experts in the field to learn what they know now -- 14 years into the campaign -- and what more can be done to save babies.

A difficult diagnosis

Spotting SIDS would seem fairly straightforward, but the truth is quite the opposite. And that makes it very hard to know exactly how and why babies succumb, or why the highest rates occur in infants between 2 and 4 months old. The condition can be diagnosed only when a death has been carefully investigated -- including an autopsy, a study of the scene and circumstances of death, and an examination of the baby's medical history -- so that all other possibilities can be ruled out. The process is expensive, and many counties don't have the resources to conduct such thorough investigations, says Amy Martin, M.D., chief medical examiner for Denver, Colorado. The result? Some cases may be missed. At risk for SIDS?

Government bureaucracy only compounds the problem. In 2006 the CDC acknowledged that its SIDS reporting form, which each medical examiner's office is charged with completing, was unnecessarily confusing; the revised form can be completed almost entirely by checking boxes. But for on-the-ground forensic pathologists, says Dr. Martin, the new version is still problematic.

"If you don't have enough trained investigators who can go out to the death scene, you're going to have a difficult time filling out a form like that -- not to mention getting to the bottom of what really happened," she says.

And yet even when resources are available, identifying a true case of SIDS can be challenging. When a baby is found lying on her tummy -- or in a bed with adults, or a crib full of soft toys -- the coroner can't rule out the possibility that the baby was accidentally smothered and may call it "possible accidental asphyxia" or "threats to breathing" rather than SIDS. That's why some states today report no SIDS deaths at all, despite the fact that babies still die there every year, says Fern R. Hauck, M.D., associate professor of family medicine and public health sciences at the University of Virginia.

As Melissa Haberzettl found out, this variation in labeling -- a phenomenon called code-shifting -- can happen if the examiner discovers a possibly unrelated underlying condition as well. Five weeks after offering a preliminary assessment that Jake had died of SIDS, the Colorado Springs coroner changed his diagnosis. Even though the baby showed no signs of illness, the medical examiner concluded that Jake had died of viral pneumonia. "I kept asking, 'How can a healthy baby die of pneumonia?' but I never got a straight answer," says Melissa. Why moms worry

She sought out a second opinion from Henry Krous, M.D., a SIDS researcher at Rady Children's Hospital in San Diego, California. In his view, the local examiner had missed a perfectly obvious case of SIDS: "With viral pneumonia, infants don't die suddenly without getting sick first," says Dr. Krous. "If one has a degree of pneumonia that can be seen only with a microscope, and then the infant dies, he dies with it, not of it."

Regardless of how or why it happens, code-shifting helps to explain why SIDS deaths have dropped in the past 14 years while other sudden infant deaths, like those attributed to accidental suffocation or even, simply, undefined causes, have increased significantly. If true SIDS cases are being assigned a wide variety of other diagnoses, it makes it nearly impossible for researchers to get a good handle on what's happening with the rates and risk factors right now, says Dr. Hauck. That's why for parents, it's more important than ever to follow the safe-sleep recommendations, including putting babies down on their backs, says Dr. Krous. "Nothing we know at the present time will absolutely prevent SIDS, but the risk can be substantially reduced."

What we know so far

Despite the challenges, SIDS research goes on. And though much remains to be learned, scientists do have some answers.

For instance, they know that certain infants, such as African-American, Native American, and premature babies, are at particular risk, and that certain situations (including sleeping on a soft surface and exposure to secondhand smoke) raise the odds for all babies. They also know that babies who sleep on their stomachs or sides face the biggest danger: They have twice the risk of dying from SIDS as babies who sleep on their backs. When a baby's face is turned toward the bedding, he's in a position to re-breathe the carbon dioxide he exhales, which limits the amount of oxygen he takes in. Baby gear dangers

"When they aren't getting enough oxygen, most babies will do something to change their environment -- they'll turn their heads, or they'll sigh, or they'll yawn," says Rachel Moon, M.D., an associate professor of pediatrics at George Washington University School of Medicine in Washington, DC. "But babies who die of SIDS don't wake up when they get into trouble, and we don't fully understand why."

One of the most plausible theories may be a brain-stem abnormality that affects the brain's ability to make and use serotonin -- a theory corroborated by a new Italian study that found that serotonin overproduction caused SIDS-like deaths in mice -- and it may be responsible for well over half of all cases.

Along with its role affecting mood, serotonin helps regulate breathing and arousal. If that arousal center isn't functioning properly, a baby sleeping in a position that limits his oxygen may not wake up in time. This discovery, made by researchers at Children's Hospital Boston, helps explain why SIDS rates drop dramatically after six months and disappear entirely at one year: The brain stem continues to mature, and even abnormal brain stems are eventually able to process serotonin appropriately.

The many sides of SIDS

As encouraging as this research is, it's become increasingly clear that the syndrome likely has several biological explanations, with different babies dying for different physiological reasons -- and that complicates the mystery even more.

Along with brain-stem problems, researchers are also looking into undiagnosed genetic anomalies that cause no symptoms but are ultimately fatal. A metabolic disorder called MCADD (medium chain acyl-CoA dehydrogenase deficiency), for instance, impairs the baby's ability to process fatty acids, eventually causing a sudden and fatal interruption in heart function. Another condition is long QT syndrome, an electrical disorder in the heart that causes sudden bursts of extremely rapid heartbeats and can lead to cardiac arrest. MCADD and long QT syndrome account for fewer than 15 percent of SIDS cases, but both disorders can be successfully treated if caught in time by a blood test; unfortunately, these tests aren't routine in most states.

Although some infants seem to be at greater genetic risk for SIDS, it's also possible that all babies are susceptible if the factors are strong enough at the time of greatest vulnerability. "It probably takes more of a stressor to tip a baby who has no predisposition over into SIDS than it takes for a genetically susceptible baby, but it could still happen," says Dr. Moon. Guide to safe sleeping

Preliminary research also suggests that babies who begin daycare before 4 months of age, like Jake Haberzettl, may be at increased risk as well. In the most recent AAP analysis, about 20 percent of all SIDS deaths occurred while the baby was in the care of someone other than a parent. One third of the infants died during the first week of childcare, and half those deaths occurred on the very first day.

"It may be that starting a new routine interrupts the baby's sleep cycle, so that when he finally does fall asleep, he sleeps too deeply," says Dr. Moon. It may also be that some providers don't recognize the risks of tummy sleeping. The danger? Babies who are accustomed to sleeping on their backs are 18 times more likely to die from SIDS when put down to sleep on their stomachs. That's why it's important for parents to emphasize safe-sleeping practices with their providers, and try to use only a licensed facility.

Eventually, researchers hope that it will be possible to create a diagnostic test to identify the babies most at risk for SIDS. "But our real dream is to develop some sort of protection to use through the risk period," says Dr. Krous. Reaching that goal will take a lot more funding, a lot more research, and more accurate information from death-scene investigations. As Dr. Krous says, "That's a long way off, but that's the dream. To save lives."

Melissa Haberzettl shares this dream. In March, she gave birth to a second son, Dylan Jacob, whose middle name is a tribute to the older brother he'll never know. "I was nervous about trying to get pregnant again," says Melissa, "but Rudy and I both said to ourselves, 'We have to try.' " (To make sure his risk was low, Dylan was tested for both MCADD and long QT syndrome, but he has neither.) And she continues to keep up with SIDS research. "I'm hopeful that in my lifetime, people will say, 'SIDS? What's that?' And no other family will have to go through what we did when Jake died."

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All About Sudden Infant Death Syndrome

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