Project Summary In this K99/R00 Pathway to Independence application, Dr. Christine O’Brien proposes detailed training in optoelectronics and postpartum hemorrhage physiology that will strategically complement her expertise in the development of optical diagnostics for women’s health. The training plan is paired with scientific studies that will develop and utilize a novel multifunctional optical device for early detection of postpartum hemorrhage in pregnant patients. The primary goal of Dr. O’Brien is to become an independent researcher in women’s health technologies. The rigorous training described and the outstanding team of mentors in wearable optical devices (Drs. Achilefu and Culver) and translational maternal health research (Drs. England and Stout) will ensure her success in reaching this ambitious goal. Through her training plan, Dr. O’Brien will gain 1) expertise in development of small, portable optoelectronic devices; 2) strengthened knowledge of postpartum hemorrhage physiology and research; and 3) knowledge of strategies and best practices for running a successful and innovative independent lab. Postpartum hemorrhage (PPH), defined as the loss of 1 L of blood or more within 24 hours after birth, is the leading cause of maternal mortality worldwide. Importantly, PPH is the most preventable cause of maternal mortality, and the leading factors causing preventable PPH are delay in diagnosis and treatment. Thus, there is an urgent need for an early and accurate alert system that can facilitate prompt treatment to prevent PPH-related mo. During hemorrhage, the body tries to compensate for blood loss by shunting blood from the periphery to vital organs and replenishing reduced blood volume with water from the interstitium. These compensation mechanisms help stabilize the patient, delaying the time until global vascular indicators such as blood pressure and heart rate are affected, the current measurements used to predict PPH. Thus, monitoring of peripheral blood flow and blood content can yield early indicators of hemorrhage. Optical technologies are well suited to noninvasively measure blood flow and blood content. Preliminary experiments run by the candidate demonstrated sensitivity to reduced perfusion in vivo and measured significant differences between blood samples diluted to physiologic levels seen during PPH using complimentary optical approaches. Based on this preliminary data, she hypothesizes that early changes in peripheral blood flow and water transfer from interstitium to the vasculature will be detected using wearable optical techniques, and such changes can detect early stages of PPH. The applicant proposes to develop a multifunctional wearable optical device to measure these early responses towards the development of an early warning system for improved PPH management.