Fetal monitoring using a wearable ultrasound patch for high-risk pregnancies.

The rapid and complex nature of fetal development requires meticulous prenatal monitoring to ensure optimal pregnancy outcomes1. Cardiotocography, which continuously records the fetal heart rate and uterine contractions, often leads to inaccurate diagnoses and unnecessary interventions2. Ultrasonography is a cornerstone of fetal monitoring and diagnosis, but it is highly dependent on specialized sonographers, limiting its availability3. Additionally, current ultrasound methods provide only snapshot evaluations4. Even in very high-risk pregnancies, it is rare to have fetal ultrasound assessments more than once per day5. Here we report a wearable ultrasound patch (UPatch) for continuous and autonomous fetal monitoring. The UPatch can acquire anatomical structures and blood flow velocities, with signal qualities comparable to those of handheld clinical ultrasound devices. Real-time image segmentation allows the autonomous tracking of target vessels and thus the acquisition of continuous blood flow spectra during fetal and maternal movements without a sonographer. We validated the UPatch accuracy on 62 pregnancies, and the continuous monitoring data on 52 pregnant women aligned with stratified perinatal conditions, including healthy, small for gestational age, large for gestational age, gestational diabetes, pre-eclampsia, and gestational hypertension. The UPatch introduces new capabilities for prenatal care and offers critical evidence for studying fetal complications in high-risk pregnancies.