Abstract: Postpartum hemorrhage (PPH) is the leading cause of maternal death worldwide and disproportionately affects minority populations. PPH is defined as a large loss of blood within 24 hours of birth. If detected early enough, effective clinical management solutions exist that significantly reduce mortality. Current standard of care for detecting PPH rely on vital sign monitoring and visually inspecting the mother’s pad to estimate blood loss. However, visual inspection of pads is subjective and error prone while deterioration in vital signs are delayed indicators of maternal blood volume changes. Consequently, early and accurate detection of PPH remains a significant clinical challenge. Vasowatch LLC is developing an automated, continuous, and minimally burdensome monitoring system, called the Momitor, that can (1) accurately and rapidly identify symptoms of PPH and (2) deliver real-time and actionable clinical decision support linked to the identified PPH symptoms. The Momitor system will consist of a wearable device worn on an extremity consisting of LEDs, phototransistors, Wi-Fi radio, and battery. The non-invasive wearable will collect photoplethysmography (PPG) waveform data, run an algorithm that identifies the onset of waveform changes suggestive of PPH, and alert clinical staff to assess the mother through a cloud-based system with SMS and dashboard alerting capabilities. During PPH the body automatically diverts blood from non-vital extremities to vital organs as a lifesaving measure – which delays deterioration in vital signs. Consequently, rather than relying on error-prone visual inspection of sanitary pads and monitoring for delayed vital sign changes, the Momitor aims to screen for the mother’s automatic compensatory response consistent with PPH and hypovolemia. In this Phase I STTR, we will demonstrate proof-of- concept for detecting PPH before vital sign deterioration based on a modified compensatory reserve estimation by demonstrating an algorithm that can accurately detect PPH before existing standard of care, prototyping a wearable device that can collect and analyze PPG data for PPH from admission to 24-hours postpartum. Receipt of NIH funds will allow us to demonstrate proof-of-concept of the Momitor and provide sufficient evidence to pursue FDA Breakthrough Device designation. We believe this solution will address an urgent need and will broadly be appealing to hospitals, resulting in lower costs and greatly improved outcomes for patients – regardless of race. Expansion into non-hospital- based birth centers will follow.