A self-contained wearable sensor device configured to be secured directly or indirectly to a pregnant user carrying a fetus and configured for monitoring for an aortocaval compression condition of the user, the wearable sensor device comprising: one or more sensors configured to generate sensor signals; a processor; wherein the wearable sensor device further comprises: computer instructions stored in computer-readable memory and executable by the processor to: determine, based on the received sensor signals from the one or more sensors of the wearable sensor device, both: (a) a sensor-based physical orientation value representing a physical orientation of the user based on the received sensor signals; (b) at least one sensor-based biometric parameter value representing at least one biometric parameter comprising at least one of a heart rate or heart rate variability of the user or a heart rate or heart rate variability of the fetus; dynamically adjust an aortocaval compression condition threshold as a variable function of one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value; compare the other one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value to the dynamically adjusted aortocaval compression condition threshold; identify an aortocaval compression condition based at least on the results of the comparison; automatically generate a repositioning alert in response to identifying the aortocaval compression condition; and output the repositioning alert to the user via an alert mechanism. one or more sensors configured to generate sensor signals; a processor; wherein the wearable sensor device further comprises: computer instructions stored in computer-readable memory and executable by the processor to: determine, based on the received sensor signals from the one or more sensors of the wearable sensor device, both: (a) a sensor-based physical orientation value representing a physical orientation of the user based on the received sensor signals; (b) at least one sensor-based biometric parameter value representing at least one biometric parameter comprising at least one of a heart rate or heart rate variability of the user or a heart rate or heart rate variability of the fetus; dynamically adjust an aortocaval compression condition threshold as a variable function of one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value; compare the other one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value to the dynamically adjusted aortocaval compression condition threshold; identify an aortocaval compression condition based at least on the results of the comparison; automatically generate a repositioning alert in response to identifying the aortocaval compression condition; and output the repositioning alert to the user via an alert mechanism. determine, based on the received sensor signals from the one or more sensors of the wearable sensor device, both: (a) a sensor-based physical orientation value representing a physical orientation of the user based on the received sensor signals; (b) at least one sensor-based biometric parameter value representing at least one biometric parameter comprising at least one of a heart rate or heart rate variability of the user or a heart rate or heart rate variability of the fetus; (a) a sensor-based physical orientation value representing a physical orientation of the user based on the received sensor signals; (b) at least one sensor-based biometric parameter value representing at least one biometric parameter comprising at least one of a heart rate or heart rate variability of the user or a heart rate or heart rate variability of the fetus; dynamically adjust an aortocaval compression condition threshold as a variable function of one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value; compare the other one of (a) the sensor-based physical orientation value or (b) the at least one sensor-based biometric parameter value to the dynamically adjusted aortocaval compression condition threshold; identify an aortocaval compression condition based at least on the results of the comparison; automatically generate a repositioning alert in response to identifying the aortocaval compression condition; and output the repositioning alert to the user via an alert mechanism.