Noninvasive method to find oxygen saturation of the fetus using photoplethysmogram

This is a survey paper done on all the methods which are trying to measure oxygen saturation of the fetus using PPG signal non invasively. Lack of oxygen in the baby's blood can result in brain damage and, in the worst cases, death. Although every unborn child has a reserve supply of oxygen (oxygen margin of safety) to draw upon during labor, exactly how large a margin and how long it lasts is unknown. Until now, there has been no reliable way to measure the oxygen saturation of a fetus during labor directly and continually. Traditionally, physicians assess the status of the fetus by monitoring fetal heart rate and uterine activity (contractions). Photoplethysmograph technology consists of infrared light emitting diodes and photo detector by which pulse rate can be measured non invasively. During trimester time of pregnant lady oxygen saturation of fetus will be measured. Monitoring fetal heart rate is ongoing observation on human fetal physiology. In same way detection of fetal oxygen saturation will also be a ongoing observation for human fetal physiology. Expected outcome of this early detection reduces the risk of fetal morbidity and mortality. The approach from literature survey can be signal conditioning and conversion is applied to the recorded values. Digital synchronous detection and preprocessing techniques are applied to segregate the fetal heart rate from the mixed signal (mother + fetal) by adaptive noise cancelling techniques, whereas PPG from the mother's index finger is the reference input. Removal of the maternal values from the mixed signal provides the oxygen saturation.