Approximately 60% of babies have jaundice, according to the CDC. Jaundice occurs when a newborn’s liver is not sufficiently developed to take over the chore of removing bilirubin from the baby’s blood, which was done by the mother’s liver prior to birth. Untreated jaundice can result in brain damage and a scary menu of additional serious health problems. Hospitals monitor newborns closely for jaundice after birth; a visit to the pediatrician a day or two after discharge includes a bilirubin check. Jaundice is often easy to observe from its characteristic yellowing skin, but it’s not always noticeable, especially with newborn babies of color. A better check of a baby’s bilirubin level requires a light meter placed on the forehead. A blood test is the most accurate way to measure bilirubin.

Direct light exposure (phototherapy) on the skin is the most common treatment method for jaundice, although doctors might treat severe cases of very high bilirubin levels with a blood exchange transfusion. We first wrote about newborn jaundice treatment technology in 2015 when we covered NeoMedLight’s light blanket with fiber optic material woven into textiles. We also wrote about TheraB Medical’s SnugLit, a wearable phototherapy garment.

Wearables now hope to address the problem of diagnosing jaundice. Researchers from Yokohama National University’s Graduate School of System Integration and Yokohama City University’s Graduate School of Medicine Department of Pediatrics developed a wearable device for babies that continuously monitors pulse rate, blood oxygen saturation, and bilirubin level. The team published their results in Science Advances.

The new device uses LEDs to transmit light to the skin on the newborn’s forehead. According to the study report and a news release from Japan Agency for Medical Research and Development, the wearable consistently measured bilirubin independently, even during phototherapy. The team tested the device with 50 babies.

The results were insufficiently accurate for clinical decision support, a failure the researchers believe is due to the device’s overall thickness. The group’s next steps include increasing the device flexibility and using thin film batteries instead of the coin cell battery used with the first device. The researchers also plan to develop a combined phototherapy device that also monitors bilirubin level.