Patent Publication Number: US-2023157594-A1

Title: Systems, devices, and methods for performing fetal oximetry and/or fetal pulse oximetry using a transvaginal fetal oximetry probe, transcervical fetal oximetry probe, and/or transurethral fetal oximetry probe

Description:
RELATED APPLICATION 
     This patent application is an INTERNATIONAL/PCT application claiming priority to U.S. Provisional Patent Application No. 62/994,058, filed on 24 Mar. 2020 and entitled “SYSTEMS, DEVICES, AND METHODS FOR PERFORMING FETAL OXIMETRY AND/OR FETAL PULSE OXIMETRY USING A TRANSVAGINAL AND/OR TRANSCERVICAL FETAL OXIMETRY PROBE,” which is incorporated in its entirety herein. 
    
    
     FIELD OF INVENTION 
     The present invention is in the field of medical devices and, more particularly, in the field of fetal oximetry, fetal pulse oximetry, and fetal tissue oxygenation. 
     BACKGROUND 
     Oximetry is a method for determining the oxygen saturation of hemoglobin in a mammal&#39;s blood. Typically, 90% (or higher) of an adult human&#39;s hemoglobin is saturated with (i.e., bound to) oxygen while only 30-60% of a fetus&#39;s blood is saturated with oxygen. Pulse oximetry is a type of oximetry that uses changes in blood volume through a heartbeat cycle to internally calibrate hemoglobin oxygen saturation measurements of the arterial blood. 
     Current methods of monitoring fetal health, such as monitoring fetal heart rate, are inefficient at determining levels of fetal distress and, at times, provide false positive results indicating fetal distress that may result in the unnecessary performance of a Cesarean delivery. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The present invention is illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which: 
         FIG.  1 A  is a block diagram illustrating an exemplary system for determining a level of oxygen saturation for fetal hemoglobin and/or whether meconium is present in the amniotic fluid of a pregnant mammal, in accordance with some embodiments of the present invention; 
         FIG.  1 B  is a block diagram of an exemplary processor-based system that may store data and/or execute instructions for the processes disclosed herein, in accordance with some embodiments of the present invention; 
         FIG.  1 C  is a block diagram of an exemplary transabdominal fetal oximetry probe, in accordance with some embodiments of the present invention; 
         FIG.  2 A  is a diagram illustrating a cross-section view of a pregnant human woman with a first exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant mammal&#39;s endocervical canal and proximate to her cervix, in accordance with some embodiments of the present invention; 
         FIG.  2 B  is a diagram illustrating the first exemplary transvaginal/transcervical fetal oximetry probe positioned proximate to an approximation of maternal tissue, in accordance with some embodiments of the present invention; 
         FIG.  2 C  is a diagram illustrating a cross-section view of a pregnant human woman with the first exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant woman&#39;s endocervical canal and coincident with the pregnant woman&#39;s fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 D  is a diagram illustrating the first exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant mammal&#39;s endocervical canal and proximate to an approximation of a fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 E  is a diagram illustrating a cross-section view of a pregnant human woman with a second exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant mammal&#39;s endocervical canal and proximate to her cervix, in accordance with some embodiments of the present invention; 
         FIG.  2 F  is a diagram illustrating the second exemplary transvaginal/transcervical fetal oximetry probe positioned proximate to an approximation of maternal and fetal tissue, in accordance with some embodiments of the present invention; 
         FIG.  2 G  is a diagram illustrating a cross-section view of a pregnant human woman with the second exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant woman&#39;s endocervical canal and coincident with the pregnant woman&#39;s fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 H  is a diagram illustrating the second exemplary transvaginal/transcervical fetal oximetry probe positioned within the pregnant mammal&#39;s endocervical canal and proximate to an approximation of a fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 I  is a diagram illustrating a cross-section view of a pregnant human woman with an exemplary transurethral fetal oximetry probe positioned within the pregnant mammal&#39;s bladder and proximate to a wall of the bladder closest to her fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 J  is a diagram illustrating the exemplary transurethral fetal oximetry probe positioned proximate to an approximation of maternal and fetal tissue, in accordance with some embodiments of the present invention; 
         FIG.  2 K  is a diagram illustrating a cross-section view of a pregnant human woman with a first exemplary transurethral fetal oximetry probe/catheter combination positioned within the pregnant mammal&#39;s bladder and proximate to a wall of the bladder closest to her fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 L  is a diagram illustrating the first exemplary transurethral fetal oximetry probe/catheter combination positioned proximate to an approximation of maternal and fetal tissue, in accordance with some embodiments of the present invention; 
         FIG.  2 M  is a diagram illustrating a cross-section view of a pregnant human woman with a second exemplary transurethral fetal oximetry probe/catheter combination positioned within the pregnant mammal&#39;s bladder and proximate to a wall of the bladder closest to her fetus, in accordance with some embodiments of the present invention; 
         FIG.  2 N  is a diagram illustrating the second exemplary transurethral fetal oximetry probe/catheter combination positioned proximate to an approximation of maternal and fetal tissue, in accordance with some embodiments of the present invention; 
         FIG.  2 O  is a diagram of a cross section of the second exemplary transurethral fetal oximetry probe/catheter combination, in accordance with some embodiments of the present invention; 
         FIG.  3    is a flowchart illustrating an exemplary process for performing fetal oximetry and/or fetal pulse oximetry and/or determining fetal tissue oxygen saturation using a transvaginal/transcervical fetal oximetry probe, in accordance with some embodiments of the present invention; 
         FIG.  4    is a flowchart illustrating an exemplary process for performing fetal oximetry and/or fetal pulse oximetry and/or determining fetal tissue oxygen saturation using both a transabdominal fetal oximetry probe and a transvaginal and/or transcervical fetal oximetry probe, in accordance with some embodiments of the present invention; 
         FIG.  5    is a flowchart illustrating an exemplary process for performing fetal oximetry and/or fetal pulse oximetry and/or determining fetal tissue oxygen saturation using both a transabdominal fetal oximetry probe and a transvaginal/transcervical fetal oximetry probe, in accordance with some embodiments of the present invention; 
         FIG.  6    is a flowchart illustrating a process for verifying a determination of fetal hemoglobin and/or tissue oxygen saturation made by a transabdominal fetal oximetry probe using a transvaginal/transcervical fetal oximetry probe, in accordance with some embodiments of the present invention; and 
         FIG.  7    is a flowchart illustrating a process for determining an overall fetal hemoglobin using a detected electronic signal from a transabdominal fetal oximetry probe and a detected electronic signal from a transvaginal/transcervical fetal oximetry probe, in accordance with some embodiments of the present invention. 
     
    
    
     Throughout the drawings, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components, or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the drawings, the description is done in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention as defined by the appended claims. 
     SUMMARY 
     Systems, devices, and methods for performing fetal oximetry and/or fetal pulse oximetry using a transvaginal fetal oximetry probe, transcervical fetal oximetry probe, and/or transurethral fetal oximetry probe are described herein. Exemplary transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and transurethral fetal oximetry probes may include a light source, one or more detectors, and a housing. For transvaginal fetal oximetry probes and transcervical fetal oximetry probes, the light source may be configured to project light of a plurality of wavelengths into the endocervical canal of a pregnant mammal to be incident on a fetus within the pregnant mammal&#39;s abdomen. When the transvaginal fetal oximetry probe is positioned on the outside of the cervix, the light from the light source may be incident upon the cervical tissue and other maternal tissue and/or amniotic fluid positioned between the light source and the fetus. When the transcervical fetal oximetry probe is positioned directly on the fetus when, for example, the cervix is sufficiently dilated to allow for passage of the transcervical fetal oximetry probe through the dilated cervix and positioning of the transcervical fetal oximetry probe directly on the fetus, often times the fetus&#39; head, the light from the light source may be incident directly upon the fetus. For transurethral fetal oximetry probes, the light source may be configured to project light onto the maternal tissue (e.g., bladder and uterine walls) positioned between the transurethral fetal oximetry probes and the fetus. 
     Detectors included in transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and transurethral fetal oximetry probes may be configured to detect light reflected from the fetus and, in the case of the transvaginal and transurethral fetal oximetry probes, pregnant mammal&#39;s tissue and convert the detected light into one or more detected electronic signals that may be communicated to an external processor configured to determine a level of fetal hemoglobin oxygen saturation and/or fetal tissue oxygen saturation with the detected electronic signal. 
     The transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and transurethral fetal oximetry probes disclosed herein also include a housing configured to house the light source and the one or more detectors. The housings of the transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and/or transurethral fetal oximetry probes may be configured, sized, and shaped so that they are easily inserted into an endocervical canal or urethra of the pregnant mammal. In some cases, the housing may be flexible so that it may bend with the curves and shape of the pregnant mammal&#39;s anatomy. In some embodiments, a shape and/or form factor for transvaginal fetal oximetry probes and transcervical fetal oximetry probes disclosed herein may be similar and/or the same. In some cases, a transvaginal fetal oximetry probe may be used transcervically when, for example, the cervix has dilated enough to allow for the passage of the transvaginal fetal oximetry probe through the dilated cervix so that it may be positioned directly on the fetus. 
     In some instances, the housings of the transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and/or transurethral fetal oximetry probes may include a cord that extends from the housing and may be configured to electrically couple the transvaginal fetal oximetry probe to a power source (thereby providing electrical power to the light source and one or more detectors) and/or communicate the detected electronic signal from the detector to the external processor. In some embodiments, the cord may be configured to facilitate extraction of the transvaginal fetal oximetry probe and/or transcervical fetal oximetry probe from the pregnant mammal&#39;s endocervical canal and/or extract the transurethral fetal oximetry probe from the pregnant mammal&#39;s urethra/bladder. Additionally, or alternatively, the transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and/or transurethral fetal oximetry probes disclosed herein may include a power source within the housing such as a battery that in some cases may be rechargeable. In some instances, the transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and/or transurethral fetal oximetry probes may be configured to wirelessly communicate with the external processor via, for example, a transceiver that may be, for example, Wi-Fi and/or Bluetooth enabled. 
     In some embodiments, the transvaginal fetal oximetry probes, transcervical fetal oximetry probes, and/or transurethral fetal oximetry probes disclosed herein may include a processing device (e.g., a CPU, an application-specific integrated circuit (ASIC), and/or a processor) configured to pre-process the detected electronic signal. The preprocessing may include filtering the signal to reduce noise and/or filter out artifacts in the signal caused by, for example, maternal movement and/or equipment noise that may interfere with the clarity of the detected electronic signals. 
     The methods disclosed herein may include receiving a first detected electronic signal from a transabdominal fetal oximetry probe, determining a first fetal hemoglobin oxygen saturation level using the first detected electronic signal, receiving a second detected electronic signal from a transvaginal fetal oximetry probe, and then determining a second fetal hemoglobin oxygen saturation level using the second detected electronic signal. The first fetal hemoglobin oxygen saturation level may then be compared to the second fetal hemoglobin oxygen saturation level and it may be determined whether the first fetal hemoglobin oxygen saturation level and the second fetal hemoglobin oxygen saturation level are within a specified range of values and, if so, an indication of the first and second fetal hemoglobin oxygen saturation level may be provided to a user. 
     On some occasions, the first detected electronic signal may be timestamped and the determining the first fetal hemoglobin oxygen saturation level may include receiving a timestamped maternal heart beat signal, synchronizing the maternal heart beat signal and the first detected electronic signal using a timestamp of the maternal heart beat signal and a timestamp first detected electronic signal, isolating a fetal signal from the detected electronic signal by subtracting portions of the first detected electronic signal that correspond to the maternal heart beat signal, and calculating the first fetal hemoglobin oxygen saturation level using the fetal signal. Additionally, or alternatively, the second detected electronic signal may be timestamped and determining the second fetal hemoglobin oxygen saturation level may include receiving a timestamped maternal heart beat signal, synchronizing the maternal heart beat signal and the second detected electronic signal using a timestamp of the maternal heart beat signal and a timestamp second detected electronic signal, isolating a fetal signal from the second detected electronic signal by subtracting portions of the second detected electronic signal that correspond to the maternal heart beat signal, and calculating the second fetal hemoglobin oxygen saturation level using the fetal signal. 
     Additionally, or alternatively, the first detected electronic signal may be timestamped and the determining of the first fetal hemoglobin oxygen saturation level may include receiving a timestamped fetal heart beat signal, synchronizing the fetal heart beat signal and the first detected electronic signal using a timestamp of the fetal heart beat signal and a timestamp first detected electronic signal, isolating a fetal signal from the first detected electronic signal by amplifying portions of the first detected electronic signal that correspond to the fetal heart beat signal, and calculating the first fetal hemoglobin oxygen saturation level using the fetal signal. 
     Additionally, or alternatively, the second detected electronic signal may be timestamped and the determining of the second fetal hemoglobin oxygen saturation level may include receiving a timestamped fetal heart beat signal, synchronizing the fetal heart beat signal and the second detected electronic signal using a timestamp of the fetal heart beat signal and a timestamp second detected electronic signal, isolating a fetal signal from the second detected electronic signal by amplifying portions of the second detected electronic signal that correspond to the fetal heart beat signal, and calculating the second fetal hemoglobin oxygen saturation level using the fetal signal. 
     In some embodiments, a characteristic of the pregnant mammal may be received and the received characteristic may be used to determine the first and/or second fetal hemoglobin oxygen saturation level. Exemplary characteristics include, but are not limited to, maternal hemoglobin oxygen saturation level, maternal heart rate, thickness of maternal tissue the light passes through, type of maternal tissue the light passes through, maternal blood pressure, and maternal respiratory rate. 
     In some embodiments, a first detected electronic signal may be received from a transabdominal fetal oximetry probe and a first fetal hemoglobin oxygen saturation level may be determined using the first detected electronic signal. A second detected electronic signal may be received from a transvaginal fetal oximetry probe and a second fetal hemoglobin oxygen saturation level may be determined using the second detected electronic signal. Then, an overall fetal hemoglobin oxygen saturation level may be determined using the first fetal hemoglobin oxygen saturation level and the second fetal hemoglobin oxygen saturation level and an indication of the overall fetal hemoglobin oxygen saturation level may be provided to a user. 
     In some embodiments, the first detected electronic signal may be timestamped and the determining of the first fetal hemoglobin oxygen saturation level may include receiving a timestamped maternal heart beat signal, synchronizing the maternal heart beat signal and the first detected electronic signal using a timestamp of the maternal heart beat signal and a timestamp first detected electronic signal, isolating a fetal signal from the detected electronic signal by subtracting portions of the first detected electronic signal that correspond to the maternal heart beat signal, and calculating the first fetal hemoglobin oxygen saturation level using the fetal signal. Additionally, or alternatively, determining of the first fetal hemoglobin oxygen saturation level may include receiving a timestamped fetal heart beat signal, synchronizing the fetal heart beat signal and the first detected electronic signal using a timestamp of the fetal heart beat signal and a timestamp first detected electronic signal, isolating a fetal signal from the first detected electronic signal by amplifying portions of the first detected electronic signal that correspond to the fetal heart beat signal, and calculating the first fetal hemoglobin oxygen saturation level using the fetal signal. 
     Additionally, or alternatively, the second detected electronic signal may be timestamped and the determining of the second fetal hemoglobin oxygen saturation level may include receiving a timestamped maternal heart beat signal, synchronizing the maternal heart beat signal and the second detected electronic signal using a timestamp of the maternal heart beat signal and a timestamp second detected electronic signal, isolating a fetal signal from the second detected electronic signal by subtracting portions of the second detected electronic signal that correspond to the maternal heart beat signal, and calculating the second fetal hemoglobin oxygen saturation level using the fetal signal. Additionally, or alternatively, determining of the second fetal hemoglobin oxygen saturation level may include receiving a timestamped fetal heart beat signal, synchronizing the fetal heart beat signal and the second detected electronic signal using a timestamp of the fetal heart beat signal and a timestamp second detected electronic signal, isolating a fetal signal from the second detected electronic signal by amplifying portions of the second detected electronic signal that correspond to the fetal heart beat signal, and calculating the second fetal hemoglobin oxygen saturation level using the fetal signal. 
     Additionally, or alternatively, a characteristic of the pregnant mammal may be received and the first and/or second fetal hemoglobin oxygen saturation level may be determined using the characteristic of the pregnant mammal. The characteristic of the pregnant mammal may be, for example, maternal hemoglobin oxygen saturation level, maternal heart rate, thickness of maternal tissue the light passes through, type of maternal tissue the light passes through, maternal blood pressure, and/or maternal respiratory rate. 
     In another embodiment, a first detected electronic signal may be received from a transabdominal fetal oximetry probe and a first fetal hemoglobin oxygen saturation level may be determined using the first detected electronic signal. A second detected electronic signal may be received from a transurethral fetal oximetry probe and a second fetal hemoglobin oxygen saturation level may be determined using the second detected electronic signal. The first and second fetal hemoglobin oxygen saturation levels may be compared and it may be determined whether the first fetal hemoglobin oxygen saturation level and the second fetal hemoglobin oxygen saturation level are within a specified range of values (e.g., within a standard of deviation from one another) and an indication of the comparison and/or a value for the first and/or second fetal hemoglobin oxygen saturation level may be provided to a user. 
     In another embodiment, a first detected electronic signal may be received from a transabdominal fetal oximetry probe and a first fetal hemoglobin oxygen saturation level may be determined using the first detected electronic signal. A second detected electronic signal may be received from a transurethral fetal oximetry probe and a second fetal hemoglobin oxygen saturation level may be determined using the second detected electronic signal. Then, an overall fetal hemoglobin oxygen saturation level may be determined using the first fetal hemoglobin oxygen saturation level and the second fetal hemoglobin oxygen saturation level and an indication of the overall fetal hemoglobin oxygen saturation level may be provided to a user. 
     Description 
       FIG.  1    provides an exemplary system  100  for detecting and/or determining fetal hemoglobin oxygen saturation levels and/or fetal depth. The components of system  100  may be coupled together via wired and/or wireless communication links. In some instances, wireless communication of one or more components of system  100  may be enabled using short-range wireless communication protocols designed to communicate over relatively short distances (e.g., BLUETOOTH™, near field communication (NFC), radio-frequency identification (RFID), and Wi-Fi) with, for example, a computer or personal electronic device (e.g., tablet computer or smart phone) as described below. 
     System  100  includes a fetal oximetry probe  115  that includes at least one light source  105  and at least one a detector  160 . On some occasions, fetal oximetry probe  115  may include a power source such as a battery and/or port by which to couple fetal oximetry probe  115  to a power source such as an outlet. Light source  105  may include a single, or multiple light sources and detector  160  may include a single, or multiple detectors. Light source  105  may transmit light of one or more wavelengths, including near infra-red (NIR), into the pregnant mammal&#39;s abdomen. Typically, the light emitted by light source  105  is focused or emitted as a narrow beam to reduce spreading of the light upon entry into the pregnant mammal&#39;s abdomen. Light source  105  may be, for example, a LED, and/or a LASER that may be coupled to a fiber optic cable. On some occasions, the light sources may be one or more fiber optic cables optically coupled to a laser and arranged in an array. In some instances, light source  105  may be tunable or otherwise user configurable while, in other instances, light source  105  may be configured to emit light within a pre-defined range of wavelengths. Additionally, or alternatively, one or more filters (not shown) and/or polarizers may filter/polarize the light emitted by light sources  105  to be of one or more preferred wavelengths. In some cases, these filters/polarizers may also be tunable or user configurable. 
     An exemplary light source  105  may have a relatively small form factor and may operate with high efficiency, which may serve to, for example, conserve space and/or limit heat emitted by the light source  105 . In one embodiment, light source  105  is configured to emit light in the range of 770-850 nm. In some embodiments, light source  105  (or multiple light sources  105 ) may emit light of at least two different frequencies (e.g., 600 nm and 900 nm; 735 and 890 nm; 670 nm and 700 nm; 735 nm and 850 nm; or 850 nm and 890 nm). Exemplary flux ratios for light sources include but are not limited to a luminous flux/radiant flux of 175-260 mW, a total radiant flux of 300-550 mW and a power rating of 0.6 W-3.5 W. A power for a light source  105  may be approximately 200 mWcm −2 . 
     Detector  160  may be a detector configured to detect light emanating from the pregnant mammal and/or the fetus via, for example, transmission and/or back scattering and convert this light signal into an electronic signal, which may be referred to herein as a composite signal and/or a detected electronic signal. The detected electronic signal may be communicated to a computer or processor such as computer  150  and/or a receiver such as receiver  145  via, for example, an on-board transceiver and/or a wired communication link. 
     Exemplary detectors  160  include, but are not limited to, photodetectors, cameras, traditional photomultiplier tubes (PMTs), silicon PMTs, avalanche photodiodes, and silicon photodiodes. In some embodiments, the detectors will have a relatively low cost (e.g., $50 or below), a low voltage requirement (e.g., less than 100 volts), and non-glass (e.g., plastic) form factor. In other embodiments, (e.g., contactless pulse oximetry) a sensitive camera may be deployed to receive light emitted by the pregnant mammal&#39;s abdomen. For example, detector  160  may be a sensitive camera adapted to capture small changes in fetal skin tone caused by changes in cardiovascular pressure associated with fetal myocardial contractions. In these embodiments, detector  160  and/or fetal oximetry probe  115  may be in contact with the pregnant mammal&#39;s abdomen, or not, as this embodiment may be used to perform so-called contactless pulse oximetry. In these embodiments, light source  105  may be adapted to provide light (e.g., in the visible spectrum, near-infrared, etc.) directed toward the pregnant mammal&#39;s abdomen so that the detector  160  is able to receive/detect light emitted by the pregnant mammal&#39;s abdomen and fetus. 
     An exemplary quantity of photons produced by light source  105  is 0.5-2 billion per cycle or for each emission of light. In some cases, the emitted light may be modulated. 
     In some cases, fetal oximetry probe  115  may be a transabdominal fetal oximetry probe configured to be affixed to the epidermis of the pregnant mammal&#39;s abdomen. An exemplary transabdominal fetal oximetry probe is provided in  FIG.  1 C  and discussed below. 
     System  100  includes a number of optional independent sensors/probes designed to monitor various aspects of maternal and/or fetal health. These probes/sensors are a NIRS adult hemoglobin probe  125 , a pulse oximetry probe  130 , a Doppler and/or ultrasound probe  135 , a uterine contraction measurement device  140 , an electrocardiography (ECG) machine  175 , and a ventilatory/respiratory signal source  180 . 
     ECG  175  may be used to determine the pregnant mammal&#39;s and/or fetus&#39;s heart rate. In some embodiments, ECG  175  may be a fetal ECG that may be used to determine the fetus&#39;s heart rate. In some instances, ECG  175  may be used internally via, for example, placement in the endocervical canal. At times, placement of ECG  175  in the endocervical canal may be facilitated by inclusion in a transvaginal and/or transcervical probe as disclosed herein. 
     Doppler and/or ultrasound probe  135  may be configured to be placed on the abdomen of the pregnant mammal and may provide information regarding, for example, fetal depth, fetal position, orientation, and/or heart rate. Pulse oximetry probe  130  may be a conventional pulse oximetry probe placed on, for example, the pregnant mammal&#39;s earlobe and/or finger to measure the pregnant mammal&#39;s hemoglobin oxygen saturation level. NIRS adult hemoglobin probe  125  may be placed on, for example, the pregnant mammal&#39;s 2nd finger and may be configured to, for example, use near infrared spectroscopy to calculate the ratio of adult oxyhemoglobin to adult de-oxyhemoglobin. NIRS adult hemoglobin probe  125  may also be used to determine the pregnant mammal&#39;s heart rate. 
     Optionally, system  100  may include a uterine contraction measurement device  140  configured to measure the strength and/or timing of the pregnant mammal&#39;s uterine contractions. In some embodiments, uterine contractions may be measured by uterine contraction measurement device  140  as a function of pressure (e.g., measured in e.g., mmHg) over time. In some instances, uterine contraction measurement device  140  is and/or includes a tocotransducer, which is an instrument that includes a pressure-sensing area that detects changes in the abdominal contour to measure uterine activity and, in this way, monitors frequency and duration of contractions. 
     In another embodiment, uterine contraction measurement device  140  may be configured to pass an electrical current through the pregnant mammal and measure changes in the electrical current as the uterus contracts. Additionally, or alternatively, uterine contractions may also be measured via near infrared spectroscopy using, for example, light received/detected by detector  160  because uterine contractions, which are muscle contractions, are oscillations of the uterine muscle between a contracted state and a relaxed state. Oxygen consumption of the uterine muscle during both of these stages is different and these differences may be detectable using NIRS. 
     Measurements and/or signals from NIRS adult hemoglobin probe  125 , pulse oximetry probe  130 , Doppler and/or ultrasound probe  135 , and/or uterine contraction measurement device  140  may be communicated directly to computer  150  and/or to receiver  145  for communication to computer  150  and display on display device  155  and, in some instances, may be considered secondary signals. In some embodiments, measurements provided by NIRS adult hemoglobin probe  125 , pulse oximetry probe  130 , a Doppler and/or ultrasound probe  135 , uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180  may be used in conjunction with fetal oximetry probe  115  to isolate a fetal pulse signal and/or fetal heart rate from a maternal pulse signal and/or maternal heart rate. Receiver  145  may be configured to receive signals and/or data from one or more components of system  100  including, but not limited to, fetal oximetry probe  115 , NIRS adult hemoglobin probe  125 , pulse oximetry probe  130 , Doppler and/or ultrasound probe  135 , uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180 . Communication between receiver  145  and/or computer  150  and other components of system  100  may be made using wired or wireless communication. 
     In some instances, one or more of NIRS adult hemoglobin probe  125 , pulse oximetry probe  130 , a Doppler and/or ultrasound probe  135 , uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180  may include a dedicated display that provides the measurements to, for example, a user or medical treatment provider. It is important to note that not all of these probes are used in every instance. For example, when the pregnant mammal is using fetal oximetry probe  115  in a setting outside of a hospital or treatment facility (e.g., at home or work) then, some of the probes (e.g., NIRS adult hemoglobin probe  125 , pulse oximetry probe  130 , a Doppler and/or ultrasound probe  135 , uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180 ) of system  100  may not be used. 
     In some instances, receiver  145  may be configured to process or pre-process received signals so as to, for example, make the signals compatible with computer  150  (e.g., convert an optical signal to an electrical signal), improve signal to noise ratio (SNR), amplify a received signal, etc. In some instances, receiver  145  may be resident within and/or may be a component of computer  150 . In some embodiments, computer  150  may amplify or otherwise condition the received detected signal so as to, for example, improve the signal-to-noise ratio. 
     Receiver  145  may communicate received, pre-processed, and/or processed signals to computer  150 . Computer  150  may act to process the received signals, as discussed in greater detail below, and facilitate provision of the results to a display device  155 . Exemplary computers  150  include desktop and laptop computers, servers, tablet computers, personal electronic devices, mobile devices (e.g., smart phones), and the like. Exemplary display devices  155  are computer monitors, tablet computer devices, and displays provided by one or more of the components of system  100 . In some instances, display device  155  may be resident in receiver  145  and/or computer  150 . Computer  150  may be communicatively coupled to a database  170 , which may be configured to store information regarding physiological characteristic and/or combinations of physiological characteristic of pregnant mammals and/or their fetuses, impacts of physiological characteristic on light behavior, information regarding the calculation of hemoglobin oxygen saturation levels, calibration factors, and so on. 
     In some embodiments, a pregnant mammal may be electrically insulated from one or more components of system  100  by, for example, an electricity isolator  120 . Exemplary electricity insulators  120  include circuit breakers, ground fault switches, and fuses. 
     In some embodiments, system  100  may include a ventilatory/respiratory signal source  180  that may be configured to monitor the pregnant mammal&#39;s respiratory rate and provide a respiratory signal indicating the pregnant mammal&#39;s respiratory rate to, for example, computer  150 . Additionally, or alternatively, ventilatory/respiratory signal source  180  may be a source of a ventilatory signal obtained via, for example, cooperation with a ventilation machine. Exemplary ventilatory/respiratory signal sources  180  include, but are not limited to, a carbon dioxide measurement device, a stethoscope and/or electronic acoustic stethoscope, a device that measures chest excursion for the pregnant mammal, and a pulse oximeter. A signal from a pulse oximeter may be analyzed to determine variations in the PPG signal that may correspond to respiration for the pregnant mammal. Additionally, or alternatively, ventilatory/respiratory signal source  180  may provide a respiratory signal that corresponds to a frequency with which gas (e.g., air, anesthetic, etc.) is provided to the pregnant mammal during, for example, a surgical procedure. This respiratory signal may be used to, for example, determine a frequency of respiration for the pregnant mammal. 
     In some embodiments, system  100  may include a timestamping device  185 . Timestamping device  185  may be configured to timestamp a signal generated and/or provided by, for example, fetal oximetry probe  115 , Doppler/ultrasound probe  135 , pulse oximetry probe  130 , NIRS adult hemoglobin probe, uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180  with a timestamp that represents, for example, an event (e.g., time, or t, =0, 10, 20, etc.) and/or chronological time (e.g., date and time). Timestamping device  185  may timestamp a signal via, for example, introducing a ground signal into system  100  that may simultaneously, or nearly simultaneously, interrupt or otherwise introduce a stamp or other indicator into a signal generated by one or more of, for example, fetal oximetry probe  115 , Doppler/ultrasound probe  135 , pulse oximetry probe  130 , NIRS adult hemoglobin probe, uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180 . Additionally, or alternatively, timestamping device  185  may timestamp a signal via, for example, introducing an optical signal into system  100  that may simultaneously, or nearly simultaneously, interrupt or otherwise introduce a stamp or other indicator into a signal generated by one or more of, for example, fetal oximetry probe  115 , pulse oximetry probe  130 , NIRS adult hemoglobin probe, uterine contraction measurement device  140 . Additionally, or alternatively, timestamping device  185  may timestamp a signal via, for example, introducing an acoustic signal into system  100  that may simultaneously, or nearly simultaneously, interrupt or otherwise introduce a stamp or other indicator into a signal generated by one or more of, for example, fetal oximetry probe  115 , Doppler/ultrasound probe  135 , and/or ventilatory/respiratory signal source  180 . 
     A timestamp generated by timestamping device  185  may serve as a simultaneous, or nearly simultaneous starting point, or benchmark, for the processing, measuring, synchronizing, correlating, and/or analyzing of a signal from, for example, fetal oximetry probe  115 , Doppler/ultrasound probe  135 , pulse oximetry probe  130 , NIRS adult hemoglobin probe  125 , uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180 . In some instances, a timestamp may be used to correlate and/or synchronize two or more signals generated by, for example, fetal oximetry probe  115 , Doppler/ultrasound probe  135 , pulse oximetry probe  130 , NIRS adult hemoglobin probe, uterine contraction measurement device  140 , ECG  175 , and/or ventilatory/respiratory signal source  180  so that, for example, they align in the time domain. 
       FIG.  1 B  provides an example of a processor-based system  101  that may store and/or execute instructions for one or more of the processes described herein. Processor-based system  101  may be representative of, for example, computing device  1450  and/or the components of housing  125  and/or  805 . Note, not all of the various processor-based systems which may be employed in accordance with embodiments of the present invention have all of the features of system  101 . For example, certain processor-based systems may not include a display inasmuch as the display function may be provided by a client computer communicatively coupled to the processor-based system or a display function may be unnecessary. Such details are not critical to the present invention. 
     System  101  includes a bus  12  or other communication mechanism for communicating information, and a processor  14  coupled with the bus  12  for processing information. System  101  also includes a main memory  16 , such as a random-access memory (RAM) or other dynamic storage device, coupled to the bus  12  for storing information and instructions to be executed by processor  14 . Main memory  16  also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor  14 . System  101  further includes a read only memory (ROM)  18  or other static storage device coupled to the bus  12  for storing static information and instructions for the processor  14 . A storage device  20 , which may be one or more of a hard disk, flash memory-based storage medium, a magnetic storage medium, an optical storage medium (e.g., a Blu-ray disk, a digital versatile disk (DVD)-ROM), or any other storage medium from which processor  14  can read, is provided and coupled to the bus  12  for storing information and instructions (e.g., operating systems, applications programs and the like). 
     System  101  may be coupled via the bus  12  to a display  22 , such as a flat panel display, for displaying information to a user. An input device  24 , such as a keyboard including alphanumeric and other keys, may be coupled to the bus  12  for communicating information and command selections to the processor  14 . Another type of user input device is cursor control device  26 , such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor  14  and for controlling cursor movement on the display  22 . Other user interface devices, such as microphones, speakers, etc. are not shown in detail but may be involved with the receipt of user input and/or presentation of output. 
     The processes referred to herein may be implemented by processor  14  executing appropriate sequences of processor-readable instructions stored in main memory  16 . Such instructions may be read into main memory  16  from another processor-readable medium, such as storage device  20 , and execution of the sequences of instructions contained in the main memory  16  causes the processor  14  to perform the associated actions. In alternative embodiments, hard-wired circuitry or firmware-controlled processing units (e.g., field programmable gate arrays) may be used in place of or in combination with processor  14  and its associated computer software instructions to implement the invention. The processor-readable instructions may be rendered in any computer language. 
     System  101  may also include a communication interface  28  coupled to the bus  12 . Communication interface  28  may provide a two-way data communication channel with a computer network, which provides connectivity to the plasma processing systems discussed above. For example, communication interface  28  may be a local area network (LAN) card to provide a data communication connection to a compatible LAN, which itself is communicatively coupled to other computer systems. The precise details of such communication paths are not critical to the present invention. What is important is that system  101  can send and receive messages and data through the communication interface  28  and in that way communicate with other controllers, etc. 
       FIG.  1 C  illustrates an exemplary fetal probe  115 C positioned on a pregnant mammal&#39;s abdomen. The maternal tissue of the pregnant mammal&#39;s abdomen is represented as an abstraction of maternal tissue  205  and a fetus within the pregnant mammal&#39;s abdomen is represented as an abstraction of a fetus  210 . 
     Fetal probe  115 C has one light source  105  and six detectors  160 A,  160 B,  160 C,  160 D,  160 E, and  160 F, each of which have a different position relative to source  105  with first detector  160  A being the closest to source  105  and sixth detector  160 F being the furthest away from source  105 . A position of a detector  160 A- 160 F relative to source  105  may be referred to herein as a source/detector distance. In some examples, detectors  160 A- 160 F may be arranged linearly and may be positioned 1 cm apart from one another so that first detector  160 A is positioned 1 cm away from source  105 , second detector  160 B is positioned 1 cm away from first detector  160 A, third detector  160 C is positioned 1 cm away from second detector  160 B, fourth detector  160 D is positioned 1 cm away from third detector  160 C, fifth detector  160 E is positioned 1 cm away from fourth detector  160 D, and sixth detector  160 F is positioned 1 cm away from fifth detector  160 E. 
     Source  105  may project an optical signal  190  into the pregnant mammal&#39;s abdomen  205  and a resultant optical signal may be detected by one or more of detector(s)  160 A- 160 F. It is expected that the detectors positioned closer to source  105  will detect a portion of the optical signal that has been incident on the pregnant mammal&#39;s abdomen  205  but not fetus  210  and, in some embodiments, first detector  160 A and/or second detector  160 B may be positioned via, for example, setting of a source/detector distance, so that a majority, if not all, of an optical signal  190 A and  190 B detected by first and second detectors  160 A and  160 B, respectively, has only been incident of the pregnant mammal&#39;s abdomen  205  (i.e., is not incident on the fetus). Third-sixth detectors  160 C- 160 F may detect portions of the optical signal  190 C,  190 D,  190 E, and  190 F that are incident on the pregnant mammal  205  and fetus  210  as shown in  FIG.  1 C . In some cases, third detector  160 C may be positioned 3-5 cm away from the light source and sixth detector  160 F may be positioned 6-10 cm away from the light source. Additionally or alternatively, third-sixth detectors  160 C- 160 F may be positioned within 4-10 cm of the light source. 
     As the source/detector distance increases a proportion of the optical signal that corresponds to light that was incident on fetus  210  increases. Thus, optical signal  190 F may include a higher proportion of light that was incident on the fetus than, for example, optical signal  190 E or  190 D. 
       FIG.  2 A  is a diagram illustrating a cross-section view of an abdomen of a pregnant human woman with a fetus  210  positioned within a uterus  260 , wherein an exemplary transvaginal and/or transcervical fetal oximetry probe  115 D, which may also be referred to herein as a transvaginal/transcervical fetal oximetry probe  115 D is positioned within her endocervical canal  265  and proximate (i.e., touching) to her cervix  270  and  FIG.  2 B  is a close-up view of exemplary transvaginal/transcervical fetal oximetry probe  115 D shown in  FIG.  2 A  where the maternal tissue (including, for example, the cervix, amniotic sack, and/or amniotic fluid) is represented as an abstract shape  205  and the fetus is represented as an abstract shape  210 . At times, the transvaginal/transcervical fetal oximetry probe(s) discussed herein may be referred to as “transvaginal probe(s)” for the sake of brevity. Also shown in  FIG.  2 A  is the pregnant mammal&#39;s urethra  275 , bladder  280  and bladder wall  285 . 
     In some embodiments, transvaginal/transcervical fetal oximetry probe  115 D may be configured to reside within the pregnant mammal&#39;s endocervical canal for an extended period of time (e.g., hours) during, for example, labor and delivery of the fetus. Additionally, or alternatively, transvaginal/transcervical fetal oximetry probe  115 D may be configured to reside within the pregnant mammal&#39;s endocervical canal on an as-needed and/or periodic (e.g., inserted into and extracted from the endocervical canal) basis over time during, for example, the labor and delivery process. 
     Transvaginal/transcervical fetal oximetry probe  115 D includes a housing  201  with a handle  220  and a body  215 . Body  215  includes one light source  105  and three detectors  160 G,  160 H, and  160 I, each of which have a different position relative to source  105  with first detector  160 G being the closest to source  105  and third detector  160 I being the furthest away from source  105 . In some embodiments, handle  220  may include one or more optional components such as ECG machine  175 , a transceiver  240 , a processor/memory combination  245 , a power supply  250 , and/or a port  255 . Power supply  250  may be any power supply configured to provide electrical power to one or more components of transvaginal/transcervical fetal oximetry probe  115 D. In some embodiments, power supply  250  may be a battery (rechargeable or otherwise). Additionally, or alternatively, power supply may be/include an AC/DC. Port  255  may be configured to, for example, provide power to and/or act as a communications interface for transvaginal/transcervical fetal oximetry probe  115 D. Exemplary ports  255  include, but are not limited to USB ports, USB-C ports, ethernet ports and the like. In some instances, port  255  may include two or more ports. 
     Processor/memory  245  may be communicatively coupled to one or more detectors  160 G,  160 H, and/or  160 I and may be configured to receive one or more detected electronic and/or composite signals therefrom. Processor/memory  245  may also be communicatively coupled to light source  105  and may be configured to provide instructions thereto. Exemplary instructions include, but are not limited to, turning light source  105  on/off, a duration of time to project light, light modulation instructions, and/or what type (e.g., wavelength or set of wavelengths) and/or intensity of light to emit. In some embodiments, processor/memory  245  may be configured to pre-process and/or filter detected electronic signals and/or composite signal received from one or more detectors  160 G,  160 H, and/or  160 I. Exemplary pre-processing includes, but is not limited to, filtering (e.g., bandpass or Kalman filter) and/or noise reduction. One or more operations performed by processor/memory  245  may be executed using one or more sets of instructions stored thereon and/or received via, for example, port  255  and/or transceiver  240 . At times, these instructions may be updated via communications received via, for example, port  255  and/or transceiver  240 . 
     Transceiver  240  may be communicatively coupled to processor/memory  245 , power supply  250 , and/or port  255  and may be configured to communicate composite signals and/or detected electronic signals to one or more communicatively connected devices such as computer  150  and/or receiver  145 . Transceiver  240  may also be configured to receive instructions regarding the operation of transvaginal/transcervical fetal oximetry probe  115 D and provide these instructions to processor/memory  245 . Transceiver  240  may be configured to operate via wired and/or wireless communications. 
     A position of a detector  160 G- 160 I relative to source  105  may be referred to herein as a source/detector distance. In some examples, detectors  160 G- 160 I may be arranged linearly and may be positioned 1 cm apart from one another so that first detector  160 G is positioned 1 cm away from source  105 , second detector  160 H is positioned 1 cm away from first detector  160 G, and third detector  160 I is positioned 1 cm away from second detector  160 H. 
     Source  105  may project an optical signal  220  into the pregnant mammal&#39;s tissue  205  and a resultant optical signal that has reflected off of the maternal tissue  205  and/or fetus  210 , and may be detected by one or more of detector(s)  160 G- 160 I. It is expected that the detectors  160  positioned closer to source  105  may detect a portion of the optical signal that has been incident on the pregnant mammal&#39;s tissue  205  but not fetus  210  and, in some embodiments, first detector  160 G and/or second detector  160 H may be positioned via, for example, setting of a source/detector distance, so that a majority, if not all, of an optical signal  220 A and  220 B detected by first and second detectors  160 G and  160 H, respectively, has only been incident of the pregnant mammal&#39;s tissue  205  (i.e., is not incident on the fetus). Third detector  160 I may detect portions of the optical signal  220 C that are incident on the pregnant mammal&#39;s tissue  205  and fetus  210  as shown in  FIG.  2 A . In some cases, third detector  160 I may be positioned 3-5 cm away from the light source. 
       FIG.  2 C  is a diagram illustrating a cross-section view of a pregnant human woman with an exemplary transvaginal/transcervical fetal oximetry probe  115 D positioned within her endocervical canal  265 , through an opening in cervix  270  as may be the case when the cervix  270  is sufficiently dilated to allow for passage of transvaginal/transcervical fetal oximetry probe  115 D therethrough so that transvaginal/transcervical fetal oximetry probe  115 D may be positioned proximate to (in some cases touch) her fetus  210  as may be the case when transvaginal/transcervical fetal oximetry probe  115 D passes through the cervix and is placed directly on the fetus.  FIG.  2 D  is a close-up view of exemplary transvaginal/transcervical fetal oximetry probe  115 D positioned as shown in  FIG.  2 C  where the fetus is shown as an abstract shape  210 . When transvaginal/transcervical fetal oximetry probe  115 D is positioned directly next to fetus  210 , source  105  may project an optical signal  220  into the fetus  210  and a resultant optical signal may be detected by one or more of detector(s)  160 G- 160 I via, for example the optical signal reflecting off of the fetus  210  and being detected by detector(s)  160 G- 160 H. 
       FIG.  2 E  is a diagram illustrating a cross-section view of a pregnant human woman with an exemplary transvaginal and/or transcervical fetal oximetry probe  115 E, which may also be referred to herein as a transvaginal/transcervical fetal oximetry probe  115 E, positioned within her endocervical canal  265  and proximate to her cervix  270  and  FIG.  2 F  is a close-up view of exemplary transvaginal/transcervical fetal oximetry probe  115 E shown in  FIG.  2 E  where the maternal tissue (including, for example, the cervix, amniotic sack, and/or amniotic fluid) is represented as abstract shape  205  and the fetus is represented as abstract shape  210 . 
     Transvaginal/transcervical fetal oximetry probe  115 E is similar to transvaginal/transcervical fetal oximetry probe  115 D but has a different form factor in that transceiver  240 , processor/memory combination  245 , power supply  250 , and/or port  255  are positioned in body  215  instead of in handle  220  and body  215  is attached to a cord  230 . Cord  230  may include one or more wires to convey electricity and/or communications to and/or from body  215  and/or components thereof. In embodiments, cord  230  may be configured to enable the mechanical extraction of transvaginal/transcervical fetal oximetry probe  115 E from the pregnant mammal&#39;s endocervical canal. 
     Transvaginal/transcervical fetal oximetry probe  115 E may be configured with a small form factor so that it is easily inserted into and extracted from the pregnant mammal&#39;s endocervical canal. In some embodiments, transvaginal/transcervical fetal oximetry probe  115 E may be configured to reside within the pregnant mammal&#39;s endocervical canal for an extended period of time (e.g., hours) during, for example, labor and delivery of the fetus. Additionally, or alternatively, transvaginal/transcervical fetal oximetry probe  115 E may be configured to reside within the pregnant mammal&#39;s endocervical canal on an as-needed and/or periodic basis (e.g., inserted into and extracted from the endocervical canal) over time during, for example, the labor and delivery process. 
       FIG.  2 G  is a diagram illustrating a cross-section view of a pregnant human woman with an exemplary transvaginal/transcervical fetal oximetry probe  115 E positioned within her endocervical canal  265  and proximate to her fetus  210  (i.e., transvaginal/transcervical fetal oximetry probe  115 E has passed through the cervix and is placed directly on the fetus) and  FIG.  2 H  is a close-up view of exemplary transvaginal/transcervical fetal oximetry probe  115 E positioned as shown in  FIG.  2 G  where the fetus is shown as abstract shape  210 . When transvaginal/transcervical fetal oximetry probe  115 E is positioned directly next to fetus  210 , source  105  may project an optical signal  220  into the fetus  210  and a resultant optical signal may be detected by one or more of detector(s)  160 G- 160 I via, for example the optical signal reflecting off of the fetus  210  and being detected by detector(s)  160 G- 160 . 
       FIG.  2 I  is a diagram illustrating a cross-section view of a pregnant human woman with an exemplary transurethral fetal oximetry probe  115 F that has been inserted into the woman&#39;s urethra  275  and positioned within the pregnant mammal&#39;s bladder  280  proximate to a portion of the bladder wall  285  closest to the pregnant mammal&#39;s uterus  260  and her fetus  210  and  FIG.  2 J  is a diagram illustrating the exemplary transurethral fetal oximetry probe  115 F positioned proximate to maternal tissue  205  where the maternal tissue  205  includes, for example, bladder wall  285 , uterus  260 , amniotic sack, etc. 
     Transurethral fetal oximetry probe  115 F may be similar to and/or include components similar to transvaginal/transcervical fetal oximetry probe  115 D and/or transvaginal/transcervical fetal oximetry probe  115 E however, transurethral fetal oximetry probe  115 F may be configured with a form factor small enough (e.g., a 3-15 mm diameter) to enable transurethral insertion and placement of transurethral fetal oximetry probe  115 F within the bladder  280 . Transurethral fetal oximetry probe  115 F may be configured to project light into the maternal tissue  205  and detect a plurality of optical signals  220 A,  220 B, and  220 C as shown in  FIG.  2 J  resultant therefrom. 
     Although transvaginal/transcervical fetal oximetry probe  115 D and  115 E and transurethral fetal oximetry probe  115 F are shown to include 3 detectors, it will be understood by those of skill in the art that transcervical fetal oximetry probe  115 D and  115 E and/or transurethral fetal oximetry probe  115 F may include any appropriate number (e.g., 1, 2, 4, 5, 6) of detectors  160 . 
     On some occasions when, for example, the pregnant mammal undergoes an epidural for analgesia from labor contractions, the pregnant mammal may require urinary catheterization. On these occasions, use of a device that is both a transurethral fetal oximetry probe and a catheter may be desired so that, for example, only one device needs to be inserted into the pregnant mammal&#39;s urethra  275  and/or bladder  280  to be positioned on a portion of bladder wall  285  proximate to the pregnant mammal&#39;s uterus  260  and fetus  210 . The transurethral fetal oximetry probe/catheter combinations disclosed herein may be used to gather data (typically in the form of detected electronic signals that correspond to an optical signal that was incident on the tissue of a pregnant mammal and/or her fetus) and/or execute any of the methods disclosed herein in a similar manner as a stand-alone transurethral fetal oximetry probe without the catheter components. 
     One exemplary embodiment of a first combined transurethral fetal oximetry probe/catheter  115 G positioned within the pregnant mammal&#39;s bladder  280  and proximate to a wall of the bladder  285  closest to her fetus is shown in  FIG.  2 K  and  FIG.  2 L  is a diagram illustrating the first combined transurethral fetal oximetry probe/catheter positioned proximate to an approximation of maternal and fetal tissue. The first exemplary transurethral fetal oximetry probe/catheter combination  115 G includes all the components of transurethral fetal oximetry probe  115 F along with components of an intermittent urinary catheter such as a tube  282  with a lumen therein  284  configured to allow urine passing through an opening  286  positioned in tube  282  to be evacuated from the pregnant mammal&#39;s bladder. Tube  282  also includes a coupling  288  configured to facilitate the coupling of tube  282  to, for example, a bag or other receptacle (not shown) for the collection of urine evacuated from the bladder. 
       FIGS.  2 M and  2 N  provide a different, or second, embodiment of a combined transurethral fetal oximetry probe/catheter  115 H where  FIG.  2 M  is a diagram illustrating a cross-section view of a pregnant human woman with transurethral fetal oximetry probe/catheter combination  115 H positioned within the pregnant mammal&#39;s bladder  280  and proximate to a wall of the bladder  285  closest to her fetus. Second exemplary transurethral fetal oximetry probe/catheter combination  115 H includes all the components of transurethral fetal oximetry probe  115 F along with components of an indwelling urinary catheter such as tube  282  with lumen therein  284  configured to allow urine passing through an opening  286  positioned in tube  282  to be evacuated from the pregnant mammal&#39;s bladder. Tube  282  also includes coupling  288  and an inflatable balloon  290  that may be used to secure placement of transurethral fetal oximetry probe/catheter combination  115 H within the bladder of the pregnant mammal as shown in  FIG.  2 N . Inflatable balloon  290  may be inflated following placement in bladder  280  and deflated for extraction from bladder  280 /urethra  275  via an air/gas tube  292  which is configured with a pump coupling  294  configured to couple to an air/gas pump (not shown) that pumps air/gas into and out of a lumen within air/gas tube  292  for the respective inflation/deflation of inflatable balloon  290 . 
       FIG.  2 O  is a diagram of a cross section of the second exemplary transurethral fetal oximetry probe/catheter combination that shows tube  282 , lumen  284 , and air/gas tube  292  within a sidewall of tube  282 .  FIG.  2 O  also shows cord  230  positioned on top of tube  282 . 
     Cord  230  of first and/or second exemplary transurethral fetal oximetry probe/catheter combination  115 G and  155 H may be separate from and/or affixed to tube  282 . When cord  230  is affixed to tube  282 , the affixation may be accomplished by any appropriate means including, but not limited to, chemical or heat bonding and/or use of a sleeve and/or strap to bind cord  230  to tube  282 . Cord  230  may diverge from tube  282  at the end of tube furthest away from the fetal oximetry probe portion of first and/or second exemplary transurethral fetal oximetry probe/catheter combination  115 G and  155 H so that, for example, cord  230  may be coupled to an external device, such as a computer like computer  150  and/or power source. 
       FIG.  3    is a flowchart illustrating a process  300  for performing fetal oximetry and/or fetal pulse oximetry using a transvaginal/transcervical fetal oximetry probe such as transvaginal/transcervical fetal oximetry probe  115 D or  115 E and/or a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F. Process  300  may also be executed to determine a level of fetal tissue oxygenation and/or a level of oxygen saturation for fetal hemoglobin. Process  300  may be performed by, for example, system(s)  100 ,  101 , and/or components thereof. 
     In step  305 , one or more detected electronic signal(s) that correspond to one or more respective optical signal(s) of one or more wavelengths detected by a detector like detector  160 G,  160 H, and/or  160 I positioned on/within a transvaginal/transcervical fetal oximetry probe like transvaginal/transcervical fetal oximetry probe  115 D when the transvaginal/transcervical fetal oximetry probe is positioned within the endocervical canal and/or cervical canal of a pregnant mammal may be received. Additionally, or alternatively, a detected electronic signal that corresponds to an optical signal of one or more wavelengths detected by a detector like detector  160 G,  160 H, and/or  160 I positioned on/within a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F may be received in step  305 . 
     The optical signal may be generated by, for example, one or more light sources like light source  105  and may be detected via, for example, reflection and/or back scattering of the projected optical signal from the pregnant mammal&#39;s tissue and/or fetus toward the detector. The detector may convert the detected optical signal to an electrical or digital signal which may be communicated to, for example, a computer or processor such as computer  150  that receives the detected electronic signal of step  305 . In some embodiments, a detected signal may be received from a different detector like detectors  160 G- 160 I as shown and discussed above with regard to  FIGS.  2 A- 2 J . 
     In the case of multiple detectors in the transvaginal/transcervical and/or transurethral fetal oximetry probe, each detector providing the detected electronic signal received in step  305  may have a different source/detector distance and each detector may be associated with a different detector identifier (e.g., a code). These different detectors may each contribute a different detected electronic signal and/or composite signal, which may include and/or be associated with a respective detector identifier so that, for example, the source/detector distance for a particular detected electronic signal within a group or set of detected electronic signals received in step  305  may be determined. 
     An exemplary range of wavelengths for the optical signals that correspond to the first detected electronic signals is between 600 and 1000 nm and may be similar to one or more of optical signals  220 A- 220 C as shown in  FIGS.  2 B ,  2 D,  2 F,  2 H, and/or  2 J. In some embodiments, the optical signal may be a broadband optical signal (e.g., white light and/or a range of, for example, 10, 15, or 20 wavelengths) and the received detected electronic signal(s) may correspond to an optical signal of a plurality of wavelengths. In some embodiments, the optical signal corresponding to one or more of the detected electronic signals, or a portion thereof, may be of a set, or known, wavelength that may be at an isosbestic point for light directed into human tissue to determine a ratio of oxygenated and de-oxygenated hemoglobin for the human&#39;s blood such as 808 nm. Light at this wavelength is reflected from oxygenated and de-oxygenated hemoglobin in the same way. 
     In step  310 , one or more characteristics of the maternal tissue and/or amniotic fluid positioned between the transvaginal/transcervical fetal oximetry probe and the pregnant mammal&#39;s fetus may be determined. Exemplary characteristics include, but are not limited to, a fetal depth (i.e., a width of tissue and/or amniotic fluid positioned between the detector of the transvaginal/transcervical fetal oximetry probe and the fetus), a degree of cervical effacement, whether the amniotic sac has ruptured or is positioned between the detector of the transvaginal/transcervical fetal oximetry probe and the fetus, characteristics of the pregnant mammal&#39;s cervix (e.g., how dilated it is and/or a thickness of the cervix), characteristics of the pregnant mammal&#39;s endocervical canal and/or cervical canal, characteristics of the pregnant mammal&#39;s bladder, a thickness of the maternal tissue between the pregnant mammal&#39;s bladder wall and the fetus, and/or a composition of the maternal tissue positioned between the pregnant mammal&#39;s bladder wall and the fetus. In some embodiments, execution of step  310  may include receiving information from, for example, an ultrasound or MRI image. Additionally, or alternatively, execution of step  310  may include determining and/or receiving a position (e.g., transcervical or not transcervical) of the detector within the endocervical canal, cervical canal, and/or bladder of the pregnant mammal. 
     In step  315 , it may be determined whether maternal information like maternal hemoglobin oxygen saturation level and/or a maternal tissue oxygen saturation level is applicable or is needed to determine fetal tissue and/or hemoglobin oxygenation levels. This determination may be based upon the one or more characteristics determined in step  310 . For example, if there is no (or minimal) maternal tissue through which blood flows positioned between the fetus and the transvaginal/transcervical fetal oximetry probe  115 D or  115 E, then maternal information like maternal hemoglobin oxygen saturation level and/or a maternal tissue oxygen saturation level may not be needed to determine isolate a fetal signal from the detected electronic signal or otherwise determined a fetal hemoglobin and/or tissue oxygenation level and process  300  may proceed to step  330 . Alternatively, if there is maternal tissue through which blood flows (e.g., cervical tissue) positioned between the fetus and the transvaginal/transcervical fetal oximetry probe  115 D or  115 E or transurethral fetal oximetry probe  115 G is supplying the detected electronic signals received in step  305 , then characteristics of that tissue, or blood flow through that tissue, may be useful in determining a fetal hemoglobin and/or tissue oxygenation level as described below and process  300  may proceed to step  320  wherein maternal information is received and/or determined. The received maternal information may be received from, for example, one or more components of system  100  and may include, for example, a hemoglobin oxygen saturation level, a maternal tissue oxygenation level, and/or a pulse oximetry reading for the pregnant mammal. For example, a pulse oximetry reading and/or hemoglobin oxygen saturation level may be received from a pulse oximetry probe like pulse oximetry probe  130  and/or a maternal pulse oximetry probe like a NIRS adult hemoglobin probe like NIRS adult hemoglobin probe  125 . Additionally, or alternatively, an indication of the tissue oxygen saturation level for the pregnant mammal may be received and/or determined in step  320  using, for example, the detected electronic signal received in step  305  and/or a diffuse optical tomography (DOT) instrument and/or may be determined by applying DOT to the detected electronic signals. Additionally, or alternatively, an indication of a hemoglobin and/or tissue oxygen saturation level for the pregnant mammal may be determined using the detected electronic signal received in step  305  and, for example, the Beer-Lambert Law or the modified Beer-Lambert Law in a manner similar that discussed below with regard to Equation 1 and/or Equation 2. In some instances, the pregnant mammal&#39;s hemoglobin and/or tissue oxygen saturation level may be used to determine how much light is incident on the fetus as discussed herein and this value (i.e., how much light is incident upon the fetus) may be used to determine the fetal hemoglobin and/or tissue oxygenation via, for example, calculations using Equation 1 and/or 2. 
     Optionally, in step  325 , the detected electronic signal(s) received in step  305  may be processed to isolate a portion thereof that was incident on the fetus. The isolated portion of the detected electronic signal(s) may be referred to herein as a fetal signal(s). In some embodiments, execution of step  325  may resemble execution of step  415  of process  400 , discussed below. In embodiments where the maternal information is not needed (in step  315 ) and/or where the pregnant mammal does not contribute to the detected electronic signal received in  305  (as may be the case when a transvaginal fetal oximetry probe is placed directly on the fetus) and/or does not produce any interference with (e.g., provide any confounding effects) the detected electronic signal received in  305  then, step  325  may be unnecessary because the pregnant mammal&#39;s tissue is not confounding the fetal oximetry measurements. 
     Step  325  may be executed using any appropriate method of isolating a fetal signal from a corresponding detected electronic signal including, but are not limited to, reducing noise in the signal via, for example, application of filtering or amplification techniques, determining a portion of the first detected electronic signal that is contributed by the pregnant mammal and then subtracting, or otherwise removing, that portion of the first detected electronic signal from the received first detected electronic signals and/or receiving information regarding a fetal heart rate and using that information to lock in (via, for example, a lock-in amplifier) on a portion of the received first detected electronic signals generated by the fetus. 
     Optionally, execution of step  325  may include pre-processing of the detected electronic signal in order to, for example, remove noise from the signal and/or confounding effects of the pregnant mammal&#39;s anatomy or physiological signals (e.g., a respiratory signal) from the detected electronic signals. Execution of the pre-processing may include, but is not limited to, application of filtering techniques to the detected electronic signal, application of amplification techniques to the detected electronic signal, utilization of a lock-in amplifier on the detected electronic signal, and so on. In some embodiments, the pre-processing may include application of a filter (e.g., bandpass or Kalman) to the detected electronic signal to reduce noise or hum in the detected electronic signal that may be caused by, for example, electronic noise generated by equipment generating and/or detecting the detected electronic signals and/or environmental equipment (e.g., a ventilator) that may, in some instances, be proximate and/or coupled to the pregnant mammal. 
     In some embodiments, execution of step  325  may include performing short separation analysis whereby a detected electronic signal corresponding to an optical signal that only passes through maternal tissue (i.e., does not penetrate deeply enough to be incident on the fetus) is used to determined characteristics of the maternal signal that is included in a detected electronic signal that includes both maternal and fetal contributions so that the maternal contributions to the detected electronic signal may be removed therefrom, which may contribute to the isolation of the fetal signal from the detected electronic signals. An exemplary short separation optical signal is optical signals  220 A and  220 B as shown in  FIGS.  2 B,  2 F, and  2 J . 
     In step  330 , a hemoglobin and/or tissue oxygen saturation level for the fetus may be determined using, for example, the modified Beer-Lambert law, which is presented as Equation 1 below, for each wavelength included in the detected electronic signal(s) under study. 
     
       
         
           
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                       
                         μ 
                         a 
                       
                       ( 
                       λ 
                       ) 
                     
                   
                   = 
                   
                     
                       - 
                       
                         1 
                         
                           r 
                           * 
                           
                             DPF 
                             ⁡ 
                             ( 
                             λ 
                             ) 
                           
                         
                       
                     
                     ⁢ 
                     
                       
                         Δ 
                         ⁢ 
                         
                           I 
                           ⁡ 
                           ( 
                           λ 
                           ) 
                         
                       
                       
                         I 
                         0 
                       
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                       
                   1 
                 
               
             
           
         
       
     
     where:
         Δμ a (λ)=the change in the absorption coefficient for a given wavelength λ over a defined time period;   r=a distance between the light source and detector;   DPF=the differential path length factor for the given wavelength λ;   I 0 =the intensity of emitted light of the given wavelength λ (e.g., the number of photons emitted by the light source) and time (t)=0; and   ΔI(λ)=the change in the measured light intensity of detected light (e.g., the number of photons detected by the detector) for the given wavelength λ over the defined time period.
 
A value for I 0  for each wavelength of light in an incident optical signal corresponding to the second det under study may be, for example, an intensity of light projected into the pregnant mammal&#39;s abdomen and/or an intensity of the light incident on the fetus as may be determined via a process disclosed herein.
       

     In embodiments where a hemoglobin and/or tissue oxygen saturation level of the pregnant mammal is received and/or determined in step  315 , the hemoglobin and/or tissue oxygen saturation level may be used to determine how much, or an intensity of, light emitted by a light source that is directed into the abdomen of the pregnant mammal is absorbed by maternal tissue or hemoglobin. A correlation between the hemoglobin and/or tissue oxygen saturation level of the pregnant mammal and how much of the incident light she may absorb for each wavelength of light may be known and/or empirically determined and these correlations may be stored in, for example, a look up table of a database like database  170  such that when a hemoglobin and/or tissue oxygen saturation level for a pregnant mammal is received and/or determined in step  315 , it may be used to look up a corresponding level of light absorption (e.g., a percentage or ratio) for the pregnant mammal. This value (the level of light absorption for the pregnant mammal) may then be applied (e.g., subtracted or multiplied) to an initial intensity of a light source when it is projecting light into the pregnant mammal&#39;s abdomen to determine the initial intensity of light incident on the fetus (I 0 ). ΔI(λ) may be the change in the measured intensity of light incident on the fetus (I 0 ) at wavelength λ and an intensity of a detected fetal signal for light of wavelength λ. 
     Once the absorption coefficient is determined via Equation 1, an indication of fetal hemoglobin oxygen saturation may be determined via, for example, calculations using Equation 2, provided below: 
       Δμ a (λ)=Δ c HbO*εHbO(λ)+Δ c Hb*εHb(λ)  Equation 2
 
     where:
         Δμ a (λ)=the change in the absorption coefficient for a given wavelength λ over a defined time period;   Δc HbO =a change in the concentration of oxygenated hemoglobin (HbO) over the defined time period;   Δc Hb =a change in the concentration of deoxygenated hemoglobin (Hb) over the defined time period;   ε HbO (λ)=the extinction coefficient for oxygenated hemoglobin (HbO) for the given wavelength; and   ε Hb (λ)=the extinction coefficient for deoxygenated hemoglobin (Hb) for the given wavelength.       

     Equation 1 may be solved for two or more wavelength pairs by inputting the change in intensity I, as a function of wavelength λ. From this, changes in absorption coefficients, Δμ a , may be determined using Equation 2 by inputting known extinction coefficients, εHbO(λ) and εHb(λ) for a particular wavelength, which may be looked up in, for example, a look-up table stored on, for example, computer  150 . The wavelength pairs used to perform the calculations of Equation 2 may be any pair of wavelengths included in the spectrum of wavelengths of the optical signal incident upon the pregnant mammal&#39;s abdomen. In some embodiments, the calculation of Equation 2 may be performed many times (e.g., 10s, 100s, or 1000s), in different combinations of wavelengths, in order to arrive at multiple values for ΔcHbO and ΔcHb which may be weighted and/or averaged according to one or more criteria to arrive at robust values (e.g., statistically valid and/or with an acceptable level of confidence and error rate) for ΔcHbO and ΔcHb. Additionally, or alternatively, the calculation of Equation 2 may be performed many times (e.g., 10s, 100s, or 1000s), to fit a plurality of wavelengths at the same time to the equation. 
     The values for ΔcHbO and ΔcHb generated via Equation 2 are relative values, not absolute values, for the concentrations of oxygenated and deoxygenated hemoglobin in the fetus&#39;s blood, which may be useful in monitoring changes in the fetal hemoglobin oxygen saturation levels of the fetus over time. In some embodiments, the determination of step  330  may also include determining an overall oxygen saturation for the fetus&#39;s hemoglobin by determining a ratio of the change in concentration of oxygenated hemoglobin to the change in concentration of total hemoglobin, which may be the sum of oxygenated and deoxygenated hemoglobin. 
     Once the fetal hemoglobin oxygen saturation level is determined in step  330 , provision of an indication of same to a user may be facilitated by, for example, display on a display device like display device  155  (step  335 ). 
       FIG.  4    is a flowchart illustrating a process  400  for performing fetal oximetry and/or fetal pulse oximetry using both a transabdominal fetal oximetry probe and a transvaginal/transcervical fetal oximetry probe, such as transvaginal/transcervical fetal oximetry probe  115 D or  115 E and/or a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F. Process  400  may also be executed to determine a level of fetal tissue oxygenation and/or a level of oxygen saturation for fetal hemoglobin. Process  400  may be performed by, for example, system(s)  100 ,  101 , and/or components thereof. 
     Initially, a detected electronic signal that corresponds to an optical signal exiting from the abdomen of a pregnant mammal and a fetus contained therein may be received (step  405 ) by, for example, a computer or processor such as computer  150 . The detected electronic signal may be received from a transabdominal fetal oximetry probe like transabdominal fetal oximetry probes  115 C,  115 D,  115 E, and/or  115 F. The optical signal may correspond to an optical signal of one or more wavelengths projected into the pregnant mammal&#39;s abdomen by, for example, one or more light sources like light source  105  and exiting the maternal abdomen via, for example, reflection, back scattering, and/or transmission. In some embodiments, the optical signal may be a broadband optical signal (e.g., white light and/or a range of, for example, 10, 15, or 20 wavelengths) and the received detected signal may correspond to an optical signal of a plurality of wavelengths. The optical signal exiting from the pregnant mammal&#39;s abdomen may be detected by a detector like detector  160 ,  160 A,  160 B,  160 C,  160 D,  160 E,  160 F,  160 G,  160 H, and/or  160 I configured to convert an optical signal (in some cases a single photon) into an electronic signal, which is the detected electronic signal. At times, the detected electronic signal may include an intensity magnitude for different wavelengths of light that may correspond to the optical signal. The detector may then directly and/or indirectly communicate the detected electronic signal to a processor as may be housed in a computer such as computer  150 . 
     The optical signal(s) that correspond to the detected electronic signal(s) may include one or more wavelengths of light generated by, for example, a light source like light source  105  and may be, for example, one or more monochromatic light source(s), one or more broadband light sources. In some embodiments, the optical signal(s) may be filtered and/or polarized. An exemplary range of wavelengths for the optical signal(s) is between 600 and 1000 nm. 
     Optionally, secondary information may be received in step  410 . Exemplary secondary information includes, but is not limited to, a fetal heart rate, a maternal heart rate, a maternal pulse signal, a respiratory signal for the pregnant mammal, a ventilatory signal for the pregnant mammal, an indication of whether meconium has been detected in the amniotic fluid of the pregnant mammal, a signal indicating uterine tone, a signal indicating a hemoglobin oxygen saturation level of the pregnant mammal, a pulse oximetry signal of the pregnant mammal and combinations thereof. In some embodiments, the respiratory signal may be received from a ventilation device providing air, oxygen, and/or other gasses to the pregnant mammal. Often times, this delivery of air, oxygen, and/or other gasses occurs with a periodic frequency (e.g., every 5 or 10 seconds) and this periodic frequency and optionally along with when, in time, the ventilation is delivered to the pregnant mammal (e.g., time=0 seconds, 5 seconds, 10 seconds, etc.) and this periodic frequency may be a secondary signal. When the secondary information is a fetal heart rate signal, the fetal heart rate signal may be received from, for example, Doppler/ultrasound probe  135  and/or an ECG device like ECG  175 . When the secondary information is a maternal heart rate signal, the maternal heart rate signal may be received from, for example, pulse oximetry probe  130 , NIRS adult hemoglobin probe  125 , and/or a blood pressure sensing device. 
     In step  415 , a portion of the detected electronic signal received in step  405  that corresponds to light that was incident on the fetus may be isolated from the detected electronic signal thereby generating a fetal signal. Step  415  may be executed by, for example, using the secondary information to detect a portion of the detected electronic signal contributed by the fetus and/or remove a portion of the detected electronic signal that is contributed by the pregnant mammal. For example, in some instances, execution of step  415  involves using the secondary information (e.g., respiratory signal for the pregnant mammal, fetal heart rate signal, and/or maternal heart rate signal) to isolate, amplify, and/or extract, a portion of the received detected electronic signal such as the portion of the signal contributed by the fetus. 
     In some embodiments, execution of step  415  may include execution of one or more procedures to, for example, reduce the signal-to-noise ratio or amplify a portion of the detected electronic signal corresponding to light that was incident upon the fetus. These processes include, but are not limited to, application of filters, subtraction of a known noise component, multiplication of two signals, normalization, and removal of a maternal respiratory signal. In some instances, execution of step  415  may include processing the detected electronic signal with a lock-in amplifier to amplify a preferred portion of the detected electronic signal and/or reduce noise in the detected electronic signal. The preferred portion of the signal may, in some instances, correspond to known quantities (e.g., wavelength or frequency) of the light incident on the pregnant mammal&#39;s abdomen. 
     In some embodiments, execution of step  415  to generate the fetal signal may include filtering the detected electronic signal using, for example, the fetal heart rate signal, the maternal heart rate signal, and/or the secondary signal. In one example, a fetal heart rate signal may be received in step  410  and correlated with the detected electronic signal in step  405 . Then, a filter (e.g., bandpass and/or Kalman) that captures a range of frequencies that may correspond to, or approximate (e.g., +/−5, 10, 15, or 20%), the fetal heart rate may be applied to the detected electronic signal so that all frequencies included in the detected electronic signal that do not correspond to the fetal heart rate (or an approximation thereof) are removed from the detected electronic signal. For example, if a fetus&#39;s heart rate is 3 Hz, then the filter may be set to filter out portions of the signal above 5 Hz and below 1 Hz. In another example, if a fetus&#39;s heart rate is 3 Hz, then the filter may be set to filter out portions of the signal above 10 Hz and below 2 Hz. In another example, if a fetus&#39;s heart rate is 3 Hz, then the filter may be set to filter out portions of the signal above 3.8 Hz and below 2.2 Hz. 
     Additionally, or alternatively, in another example, a maternal heart rate signal may be received in step  410  and correlated with the detected electronic signal in step  415 . Then, a filter that captures a range of frequencies that may correspond to, or approximate (e.g., +/−10%, 15%, or 20%), the maternal heart rate frequency may be applied to the detected electronic signal so that all frequencies included in the detected electronic signal that correspond to the maternal heart rate (or an approximation thereof) are removed from the detected electronic signal. 
     Additionally, or alternatively, in another example, a secondary signal in the form of a maternal respiratory and/or ventilatory signal may be received in step  410  and correlated with the detected electronic signal in step  405 . Then, a filter that captures a range of frequencies that may correspond to, or approximate (e.g., +/−5, 10, 15, or 20%), the maternal respiratory and/or ventilatory frequency/signal may be applied to the detected electronic signal so that all frequencies included in the detected electronic signal that correspond to the maternal respiratory and/or ventilatory rate are removed from the detected electronic signal. 
     In some embodiments, the range of frequencies filtered out from the detected electronic signal may be responsive to how dynamic, or irregular, the fetal heart rate, maternal heart rate, and/or secondary signal is so that, for example, the full (or approximately full) range of fetal signal is isolated and/or the full (or approximately full) range of the maternal signal is removed from the detected electronic signal. For example, if over the course of, for example, a 60 second interval the fetal heart rate, maternal heart rate, and/or secondary signal changes little (e.g., +/−2-15%), the then the band of frequencies filter for may be relatively narrow for that 60 second interval. Alternatively, in another example, if over the course of, for example, a 60 second interval the fetal heart rate, maternal heart rate, and/or secondary signal changes more substantially (+/−3-50%), the then the band of frequencies filter for may be relatively wider for that 60 second interval. 
     Optionally, execution of step  415  may include pre-processing the detected electronic signal in order to, for example, remove noise from the signal and/or confounding effects of the pregnant mammal&#39;s anatomy or physiological signals on the first and/or second detected electronic signals. Execution of the pre-processing may include, but is not limited to, application of filtering techniques to the detected electronic signal, application of amplification techniques to the detected electronic signal, utilization of a lock-in amplifier on the detected electronic signal, and so on. In some embodiments, execution of step  415  may include application of a filter (e.g., bandpass or Kalman) to the detected electronic signal, the filtering may reduce noise or hum in the detected electronic signal that may be caused by, for example, electronic noise generated by equipment generating and/or detecting the detected electronic signal and/or environmental equipment that may, in some instances, be coupled to the pregnant mammal. In some instances, this processing may include analysis of the detected electronic signals using information about the pregnant mammal&#39;s tissue and/or layers of the pregnant mammal&#39;s tissue that may be based upon, for example, ultrasound and/or MRI images, short separation analysis of the pregnant mammal, and/or double short separation analysis of the pregnant mammal to determine optical features and/or oxygenation of the maternal tissue and/or blood. Additionally, or alternatively, the detected electronic signal may be generated using diffuse optical tomography, frequency-domain spectroscopy, and/or time-domain diffuse correlation spectroscopy and use of these techniques may assist with the processing of the detected electronic signal. 
     In some embodiments, execution of step  415  may include correlating and/or synchronizing the fetal heart rate signal, maternal heart rate signal, and/or secondary signal (when received) with one or more the detected electronic signal(s). In some embodiments the received detected electronic signal and the secondary information may be timestamped with, for example, a baseline starting time (e.g., a date, time, etc. which may be associated with an absolute time (e.g., chronological time) and/or a simultaneous starting point of taking a measurement (e.g., time=0) resulting in the respective received detected electronic, maternal heart rate, fetal heart rate, and/or secondary signal. This timestamping may aid with the synchronization and/or correlation of the detected electronic signals with the secondary information. In some embodiments, the timestamping may take the form of, for example, an electrical ground, an optical signal introduced into an incident optical signal, and/or an acoustic signal that is introduced into the two or more of the received detected electronic, fetal heart rate, maternal heart rate, and/or secondary signals. In one example, an electrical ground, or other interruption (e.g., an intentionally introduced burst of optical noise, acoustic noise, and/or control signal) in the operation of a device that is measuring and/or providing the received detected electronic signals, fetal heart rate signal, maternal heart rate signal, and/or secondary signal may operate as a synchronizing timestamp. This timestamp may serve to provide a synchronized point in time for signals recorded by different devices which may operate on different time scales. This synchronization may assist with alignment of two or more signals so that, for example, a heartbeat provided by maternal heart rate signal may be aligned with a simultaneously generated portion of the detected electronic signal so that, in embodiments where the maternal heart rate is used to isolate the fetal signal from the detected electronic signal, the correct portion of the detected electronic signal is aligned with the proper maternal rate signal. The signals may be timestamped by, for example, timestamping device  185 . 
     The fetal signal may then be analyzed to determine a first fetal hemoglobin oxygen saturation level and/or a tissue oxygen saturation level (step  420 ) by, for example, application of the Beer-Lambert Law to the fetal signal, application of the modified Beer-Lambert Law (see e.g., Equations 1 and 2 provided herein) to the fetal signal, and/or correlating a component (e.g., intensity, wavelength of light, etc.) of the fetal signal with a known value corresponding fetal hemoglobin oxygen saturation level value, which may, in some instances, be experimentally determined and/or provided via, for example, execution of process  400  or portions thereof. In some embodiments, execution of step  420  may be similar to execution of step  330 . 
     Next, steps  305 - 325  may be performed and a second fetal hemoglobin oxygen saturation level and/or a tissue oxygen saturation level may be determined (step  425 ). Step  425  may be executed in a manner similar to the execution of step  330 . Then, the first and second fetal hemoglobin oxygen saturation levels and/or tissue oxygen saturation levels may be compared with one another in order to determine one or more differences therebetween (step  430 ). Then, in step  435 , it may be determined whether the comparison results are within a specified range of values. Execution of step  435  may include, for example, determining whether the determined first and second fetal hemoglobin and/or tissue oxygen saturation values fall within a standard of deviation (e.g., +/−1%, 3%, 5%, or 10%) or acceptable range of error when compared with one another. When the first and second fetal hemoglobin and/or tissue oxygen saturation values are not within a specified range of values (e.g., are too different from one another), the results of the comparison may be analyzed to, for example, detect errors, determine a source of errors, or otherwise trouble shoot the determinations of the first and second fetal hemoglobin and/or tissue oxygen saturation values (step  440 ). Additionally, or alternatively, execution of step  440  may include requesting and/or initiating a repeated execution of step(s)  405 - 420  and/or the combination of  305 - 325 ,  425  and  430 . When the first and second fetal hemoglobin and/or tissue oxygen saturation values are within a specified range of values (i.e., not too different from one another), an indication of the fetal hemoglobin and/or tissue oxygen saturation level may be communicated to a display device like display device  155  for display or provision to a user (step  445 ). 
       FIG.  5    is a flowchart illustrating a process  500  for performing fetal oximetry and/or fetal pulse oximetry using both a transabdominal fetal oximetry probe and a transvaginal/transcervical fetal oximetry probe, such as transvaginal/transcervical fetal oximetry probe  115 D,  115 E and/or a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F. Process  500  may also be executed to determine a level of fetal tissue oxygenation and/or a level of oxygen saturation for fetal hemoglobin. Process  500  may be performed by, for example, system  100 , system  101 , and/or components thereof. 
     In step  505 , a detected electronic signal that corresponds to an optical signal of one or more wavelengths by a detector like detector  160 G,  160 H, and/or  160 I positioned on/within a transvaginal/transcervical fetal oximetry probe like transvaginal/transcervical fetal oximetry probe  115 D when the transvaginal/transcervical fetal oximetry probe is positioned within the endocervical canal and/or cervical canal of a pregnant mammal. Execution of step  505  may be similar to the execution of step  305  described above. The detected electronic signal may by analyzed to determine one or more characteristics of the pregnant mammal&#39;s tissue and/or amniotic fluid surrounding the fetus (step  510 ). Exemplary maternal characteristics include, but are not limited to, a dimension (e.g., composition or width) of maternal tissue, a fetal depth, a degree of scattering caused by the maternal tissue, a degree of light absorbed by the maternal tissue, a maternal tissue oxygenation level, a maternal hemoglobin oxygenation level, a composition of the amniotic fluid (e.g., does it contain meconium), and/or a volume or depth of amniotic fluid positioned between the probe and the fetus. 
     Next, one or more detected electronic signal(s) that correspond to an optical signal exiting from the abdomen of a pregnant mammal and a fetus contained therein may be received (step  515 ) by, for example, a computer or processor such as computer  150 . In some embodiments, execution of step  515  may be similar to execution of step(s)  305  and/or  405 . Optionally, in step  520 , secondary information may be received. In some embodiments, execution of step  520  may be similar to execution of step(s)  320  and/or  410 . In step  525 , the fetal signal may be isolated from the detected electronic signal of step  515 . In some embodiments, execution of step  525  may be similar to execution of step(s)  325  and/or  415 . Next, the fetal signal may be analyzed using the one or more characteristics determined in step  510  to determine a fetal hemoglobin oxygen saturation level and/or a tissue oxygen saturation level (step  530 ). Execution of step  530  may resemble execution of step  420  except that when step  530  is executed, the determination of step  510  is taken into account during the execution of step  530 . Additionally, or alternatively, in some embodiments, execution of step  530  may incorporate execution of one or more steps of processes  300  and/or  400  and, in particular, may resemble execution of steps  330 ,  420 , and/or  425 . Then, an indication of the fetal hemoglobin and/or tissue oxygen saturation level may be communicated to a display device like display device  155  for display or provision to a user (step  535 ). 
       FIG.  6    is a flowchart illustrating a process  600  for verifying a determination of fetal hemoglobin and/or tissue oxygen saturation made by a transabdominal fetal oximetry probe using a transvaginal/transcervical fetal oximetry probe, such as transvaginal/transcervical fetal oximetry probe  115 D or  115 E and/or a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F. Process  600  may be performed by, for example, system  100 , system  101 , and/or components thereof. 
     Initially, steps  405 - 420  may be performed to determine a fetal hemoglobin and/or tissue oxygen saturation level using an optical signal emitted by the abdomen of a pregnant mammal that has been detected by a transabdominal fetal oximetry probe. In step  605 , it may be determined whether a value for the fetal hemoglobin and/or tissue oxygen saturation is too low (i.e., an indication that the fetus may be in distress) and/or if there is an indication of a potential error condition present in the determination of the fetal hemoglobin and/or tissue oxygen saturation (e.g., insufficient data to make a determination with a required level of confidence, a value that is above a threshold that represents a “normal” value for a fetal hemoglobin and/or tissue oxygen saturation, etc.). 
     When the value for the fetal hemoglobin and/or tissue oxygen saturation is too low and/or if there is an indication of a potential error condition present in the determination of the fetal hemoglobin and/or tissue oxygen saturation (step  605 ), steps  305 - 325  and  425 - 440  may be executed to determine a second fetal hemoglobin and/or tissue oxygen saturation level in order to, for example, verify or validate the first fetal hemoglobin and/or tissue oxygen saturation level determined in step  420 . When the value for the fetal hemoglobin and/or tissue oxygen saturation is not too low and/or if there is not an indication of a potential error condition present in the determination of the fetal hemoglobin and/or tissue oxygen saturation (step  605 ), or following execution of step  440  in process  600 , an indication of the first and/or second fetal hemoglobin and/or tissue oxygen saturation level may be communicated to a user via, for example, a display device (step  610 ). 
       FIG.  7    is a flowchart illustrating a process  700  for determining an overall fetal hemoglobin using a detected electronic signal from a transabdominal fetal oximetry probe and a detected electronic signal from a transvaginal/transcervical fetal oximetry probe, such as transvaginal/transcervical fetal oximetry probe  115 D and/or  115 E and/or a transurethral fetal oximetry probe like transurethral fetal oximetry probe  115 F. Process  700  may be performed by, for example, system  100 , system  101 , and/or components thereof. 
     Initially, steps  405 - 420  of process  400  and steps  305 - 325  of process  300  may be performed in either order (e.g., steps  405 - 420  first and then steps  305 - 325 ; or vise versa). Then, an overall fetal hemoglobin oxygen saturation level may be determined using the first and second fetal hemoglobin oxygen saturation levels (step  705 ). Step  705  may be performed by, for example, averaging the first and second fetal hemoglobin oxygen saturation levels together, adding the first and second fetal hemoglobin oxygen saturation levels together, calculating a time-weighted average of the first and second fetal hemoglobin oxygen saturation levels, and/or calculating a weighted average fetal hemoglobin oxygen saturation level using the first and second fetal hemoglobin oxygen saturation levels. In the embodiment where a weighted average is used, the first and second fetal hemoglobin oxygen saturation level may each be assigned a confidence level, or weight, based on, for example, an accuracy level of the fetal oximetry probe providing the detected electronic signals and/or a level of noise in the first and/or second fetal hemoglobin oxygen saturation level. In some embodiments, the weight, or confidence level, assigned to the first and second fetal hemoglobin oxygen saturation levels may be static, or constant, over time and may be based on empirically derived factors. Additionally, or alternatively, the weight, or confidence level, assigned to the first and second fetal hemoglobin oxygen saturation levels may be dynamic, or change, over time based on, for example one or more factors (that may be determined in situ) including, but not limited to, noise, maternal physiology, received maternal information, secondary information, and so on. 
     Hence, systems, devices, and methods for determining fetal oxygen level have been herein disclosed. In some embodiments, use of the systems, devices, and methods described herein may be particularly useful during the labor and delivery of the fetus (e.g., during the first and/or second stage of labor) because it is difficult to assess fetal health during the labor and delivery process. 
     More particularly, systems, devices, and methods for using fetal depth to select a calibration factor for calculating fetal hemoglobin oxygen saturation and/or fetal tissue oxygen saturation have been herein disclosed. In addition, systems, devices, and methods for determining fetal depth by analyzing an intensity of detected electronic signals as a function of source/detector distance have been herein disclosed. In addition, systems, devices, and methods for determining fetal depth by determining a time of flight for detected photons have been herein disclosed. In addition, systems, devices, and methods for using maternal hemoglobin oxygen saturation to determine how much light reaches the fetus (i.e., light intensity for light incident on the fetus) and then using the intensity of light incident of light incident on the fetus to analyze a detected electronic signal to determine fetal hemoglobin oxygen saturation and/or fetal tissue oxygen saturation have been herein disclosed.