Fetal Movements during Maternal Apnea in the Third Trimester of Pregnancy: An Indicator of Resistance to Intrauterine Hypoxia

Abstract: Background: It was suggested that prenatal use of the Stange test in combination with fetal biomechanics monitoring would provide an early diagnosis of excessively low fetal resistance to hypoxia, which could be a criterion for timely cesarean section to prevent stillbirths and perinatal encephalopathy. Objective: The purpose of this study was to investigate the movement dynamics of fetuses and aquarium fish during acute model hypoxia, which revealed that the duration of their immobility phase may serve as a biomarker of resistance to hypoxia. Method: This manuscript is a review of scientific articles and inventions using major international databases, taking into account the selected keywords. Results: The use of the modified Stange test has been shown to provide real-time assessment of fetal resistance to hypoxia for physicians and pregnant women. It has been shown that in normal pregnancy and high fetal resistance to hypoxia, the fetus maintains a state of immobility for at least 30 seconds during maternal apnea. In the presence of severe feta-placental insufficiency, the duration of fetal immobility during maternal apnea is less than 10 seconds. Therefore, fetal immobility during maternal apnea with a duration close to zero indicates excessively low fetal resistance to hypoxia. In such a case, an emergency cesarean section is recommended to prevent stillbirth and encephalopathy. Conclusion: The duration of fetal immobility during maternal apnea may serve as a biomarker of fetal resistance to hypoxia. Prenatal screening of fetal resistance to hypoxia can improve the outcome of pregnancy and childbirth.