ONE night last fall, Victoria Rodriguez, a pediatric hospitalist at the Ann & Robert H. Lurie Children's Hospital of Chicago, was paged from the emergency room for a consultation on a case.

An ER doctor had evaluated a 4-week-old infant, and although he couldn't find anything wrong with the baby, he hesitated to send the anxious family home.

His concern? During the night, the parents had received an alarm on their phones that the baby's heart rate and blood-oxygen level were low. The alarm had been triggered by the baby's high-tech sock, one of a new class of devices that continuously measure babies' vital signs, but the ER doctor wasn't sure how to interpret this information. There is no peer-reviewed research on the accuracy of these devices, and they have not been evaluated by the Food and Drug Administration. "Without having testing for this device, it's really hard to make sense of the alarm," Rodriguez said.

These new monitors are a far cry from the simple sound monitors that have been a nursery staple for decades. They come in several forms, with wireless electronics integrated into socks, leg bands, buttons, onesies or diaper clips that send data to parents' smartphones using Bluetooth technology. Some use motion sensors that purport to detect if a baby stops breathing, and others use pulse-oximetry probes, which shine a light through the skin to measure blood-oxygen levels. The devices can be purchased online and at major retailers for $90 to $350.

The monitors track infants' vital signs, but it's not clear how accurate this information is or how it should be used by parents and medical providers. In the case Rodriguez was consulted on, she felt she had to recommend that the baby be hospitalized for more testing. After bloodwork, an EKG and 24 hours of heart-rate and oxygen monitoring - none of which revealed problems - the infant was cleared to go home. "The child was completely fine, but those 24 hours were very nerve-racking for the parents," Rodriguez said.

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Eric Coon, an assistant professor of pediatrics at the University of Utah School of Medicine, has overseen the care of three infants with similar stories in the past few months, all admitted to the hospital from the emergency room after parents reported an alarm from a high-tech baby monitor. In each case, he said, the infants' hospital stays were "of questionable value," and he worries that this new class of monitors is causing unnecessary medical interventions.

"People think, 'Oh, all you're doing is getting more data - more data on your child. How could that be bad?' " Coon said. But "hospitalization carries a whole host of potential harms to children," including the risk of hospital-acquired infections and side effects of medical procedures, he said, along with stress and anxiety for the family and the cost of the hospital care.

"Every single medical technology has the potential to harm patients, and really the only way to know if the benefits outweigh the harms is to study it," Coon said.

Parents might assume that a monitor that measures vital signs could prevent their baby from dying of sudden infant death syndrome, or SIDS, but there's no hard evidence for this. And studies from the 1980s and 1990s of hospital-grade heart-rate and breathing monitors prescribed for home use for babies thought to be at high risk for SIDS found that the monitors didn't reduce babies' risk of dying of SIDS. These older monitors were more cumbersome - not wireless like the commercial monitors available today - but they collected similar data, and some studies reported that their use increased parental stress and fatigue.

In its guidelines on SIDS prevention, the American Academy of Pediatrics says, "Do not use home cardiorespiratory monitors as a strategy to reduce the risk of SIDS."

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Manufacturers don't claim that new monitors prevent SIDS or other sleep-related deaths, only that they offer "peace of mind" for parents and caregivers.

For example, Baby Vida's website says its oxygen monitor offers "vital peace of mind while your baby sleeps." The company's website also states, "The Baby Vida Oxygen Monitor does not prevent SIDS. It is not a medical device. . . . It's only intended use is to provide additional information to caregivers." Snuza says its movement monitors, which detect "the slightest of movements, monitoring your baby when sleeping," provides "peace of mind and supports you when you need it the most."

Because the devices do not claim to be medical equipment, they do not fall under FDA regulation, which requires manufacturers to show that devices are safe, effective and accurate.

Christopher Bonafide, a pediatrician at Children's Hospital of Philadelphia, says it's a problem that the new monitors have not been evaluated by the FDA. Bonafide was lead author of an editorial on the monitors that was published in JAMA in January. "There's no role for any type of home monitoring of healthy infants, and there are further risks with using these sort of non-FDA-approved devices in that we don't know how accurate they are and we think there could be risks of harm if parents do choose to use them," he said. FDA spokeswoman Stephanie Caccomo said that the agency is reviewing Bonafide's paper.

Reiterating what's in his editorial, Bonafide says that potential risks include burns from the devices' electronics or other skin damage caused by many hours of wear, but he's most concerned about indirect harms such as unwarranted medical interventions. Temporary pauses in breathing and periods of low blood oxygen occur occasionally in healthy infants, but if this normal variation triggers an alarm of a home monitor, it could lead to a cascade of unnecessary actions and parental anxiety, as Rodriguez and Coon saw in their patients.

Other types of constant monitoring have been shown to be unhelpful and even harmful. For example, the AAP no longer recommends continuous pulse-oximetry monitoring of children hospitalized for bronchiolitis. Studies found that when monitoring detected periods of low blood oxygen, children stayed in the hospital longer, but longer stays didn't improve health outcomes. Likewise, continuous fetal monitoring during an uncomplicated labor was found to increase a woman's chances of Caesarean delivery - and associated risks - with no health benefit to the baby. "It's so hard for medical providers not to react to data that is slightly abnormal, and sometimes it's better that we didn't know it at all," Coon said.

With the new generation of infant monitors, data is being streamed to parents from unregulated devices. "This kind of thing could lead people to try and make a clinical decision from a device that is really more like a toy in the way it's being regulated," said David Jamison, co-author of the JAMA editorial and executive director of health devices at the ECRI Institute, a nonprofit organization that reviews medical procedures and devices. The institute will be testing the safety and accuracy of home infant pulse oximeters this year, Jamison said.

Owlet, maker of one of the monitors, says it has done internal safety and accuracy testing and plans to publish results soon. Meanwhile, 80,000 families are using Owlet's sock pulse oximeter. Jane Putman, the company's public relations director, said in an email, "A number of our current customers are physicians and healthcare providers, who have expressed support for the product and the information it provides through its continued use with their own children."

She added that "due to innovations developed by Owlet to lessen false alarms, many users will use the Owlet Sock for several months without ever getting a false alarm, greatly reducing the risk of over diagnosis." Owlet also has an FDA application pending for a medical version of its pulse oximeter, available by prescription, she said.

Snuza founder Greg Gallagher said in an email that his company also is working with the FDA on a product that would be available by prescription. A Snuza monitor that detects breathing cessation has been approved as a medical device in Europe.

A small, easy-to-use, wireless pulse oximeter could be a welcome improvement over current hospital-grade devices, Bonafide said. "With evidence of their safety and accuracy, these products could be truly innovative to those patients who do need monitoring," he said, though he would recommend their use only for sick infants under the care of a physician, not for routine monitoring of healthy infants.

Some pediatricians worry that home use of vital sign monitors might falsely reassure parents about SIDS, defined as a sudden death with unexplained cause during the first year of life, and other sleep-related deaths such as those caused by suffocation. "Parents may become complacent if they are using a monitor and figure that, since the monitor is on the baby, it's okay to place the baby on her stomach to sleep or to otherwise not follow the safe sleep recommendations," Rachel Moon, a professor of pediatrics at the University of Virginia School of Medicine, wrote in an email. She was the lead author of the AAP's policy statement on safe sleep.

Moon's concern hasn't been formally studied, but Alexis Dubeif, founder of a 30,000-member Facebook group focused on infant sleep, says she believes complacency is not uncommon. "I have seen, anecdotally, a significant portion of parents who feel that it's okay to use unsafe sleep practices because they are 'protected' by their monitoring device," she wrote in an email.

To reduce the risk of SIDS, Bonafide emphasizes proven strategies. "There are things that we know help in terms of prevention of SIDS, like the bare crib and the flat mattress with a tight crib sheet. These are not sexy. These are not smartphone-integrated things," but they are effective, he said. The AAP also recommends that babies sleep in their parents' room (but not in the same bed) for the first year of life and that parents place babies on their back for sleep, avoid tobacco exposure, breast-feed, offer a pacifier and immunize babies on schedule to reduce the risk of SIDS.

Victoria Rodriguez understands the anxiety associated with SIDS. In addition to being a pediatrician, she is a mother who checks on her year-old daughter while she sleeps. When Rodriguez talks with parents, she says, she tells them to follow the AAP guidelines and not to bother with vital-signs monitors because they "don't seem to prevent bad things from happening and can cause emotional distress for families."