A soft patch no bigger than a postage stamp, placed on a mother's skin, quietly tracks her baby's heartbeat and blood flow for hours without anyone guiding it—and it caught something a conventional ultrasound would have missed. Engineers at UC San Diego have developed a wearable ultrasound patch that continuously monitors fetuses in real time, automatically following the umbilical cord as it moves, even when the mother shifts position or the baby tumbles inside the womb.
For decades, prenatal ultrasounds have been snapshots: a skilled technician applies the probe, captures images, and that's what doctors work with. But complications like preeclampsia and other high-risk conditions don't announce themselves on a schedule. They unfold over hours and days, signaling through subtle shifts in blood flow that a brief examination might never catch. Continuous monitoring could change that equation, especially for the millions of pregnant people worldwide who live far from trained sonographers or have limited access to repeated ultrasounds.
The breakthrough lies in both the patch itself and the intelligence behind it. Made of soft, flexible material that bends with the body, the device contains ultrasound transducers that produce images of the fetus and umbilical cord. But the real innovation is what happens next: autonomous tracking algorithms automatically identify and follow the cord as it drifts through the amniotic fluid, maintaining clear measurements without human intervention. This is critical because the fetus is never still—it moves, it grows, it shifts position—and previous wearable ultrasound attempts struggled with that constant motion.
Geonho (Tom) Park, a chemical and nano engineering Ph.D. student, led the work alongside fellow UC San Diego engineers Yizhou Bian, Hao Huang, and Sai Zhou under professor Sheng Xu's direction. The team tested the patch across 62 pregnancies at Jacobs Medical Center at UC San Diego Health and John Radcliffe Hospital at the University of Oxford, comparing measurements to standard handheld ultrasound machines. The results aligned closely, but continuous monitoring revealed something traditional ultrasounds typically miss: dynamic fluctuations in blood flow that unfold over time.
In one clinical case, the patch detected prolonged abnormal fetal signals that prompted doctors to intervene with an early Cesarean delivery at 29 weeks—an outcome researchers believe may have saved the baby's life. That single case hints at the technology's potential. While the study is early, the findings, published in Nature Biotechnology, suggest that wearable ultrasound could shift prenatal care from episodic snapshots to genuine continuous surveillance, catching complications while there's still time to act.
The implications ripple outward. In low-income countries where ultrasound expertise is scarce and mothers might see a technician once or twice during pregnancy, a wearable patch could offer monitoring that was previously impossible. A mother in a rural clinic could wear the device and send data to a specialist hundreds of miles away. The technology doesn't solve all challenges—access, training, and interpretation still matter—but it opens a door that was firmly shut before. As Park reflects on the research, the vision is clear: "Wearable ultrasound technology has the potential to enable continuous prenatal monitoring and improve pregnancy outcomes in ways that were previously not possible."