Fetal distress

　　The causes of fetal distress involve many aspects and can be summarized into 3 major categories.

　　One, maternal factors

　　Insufficient oxygen content in maternal blood is an important cause. In mild hypoxia, the mother may not have obvious symptoms, but it will have an impact on the fetus. The maternal factors leading to fetal hypoxia include:

　　1. Insufficient blood supply to the microarteries, such as hypertension, chronic nephritis, and hypertensive diseases in pregnancy, etc.

　　2. Insufficient oxygen-carrying capacity of red blood cells, such as severe anemia, heart failure, and pulmonary heart disease, etc.

　　3. Acute blood loss, such as antenatal hemorrhagic diseases and trauma, etc.

　　4. Obstruction of uteroplacental blood flow, such as acute labor or uterine incoordination contraction; improper use of oxytocin, causing excessive uterine contractions; prolonged labor, especially prolonged second stage of labor; overdistension of the uterus, such as polyhydramnios and multiple pregnancy; premature rupture of membranes, where the umbilical cord may be compressed, etc.

　　Two, fetal factors

　　1. Dysfunction of the fetal cardiovascular system, such as intracranial hemorrhage due to severe congenital cardiovascular diseases.

　　2. Fetal malformation.

　　Three, umbilical cord and placenta factors

　　The umbilical cord and placenta are the channels for the transmission of oxygen and nutrients between the mother and the fetus. Dysfunction of these channels inevitably affects the fetus's ability to obtain the required oxygen and nutrients.

　　1. Umbilical cord blood flow obstruction.

　　2. Low placental function, such as post-term pregnancy, placental developmental disorders (too small or too large), abnormal placental shape (membranous placenta, contour placenta, etc.), and placental infection, etc.

　　The main complications of fetal distress are cerebral ischemia and hypoxia in utero, which can lead to severe conditions such as cerebral edema, brain cell necrosis, and cerebral hemorrhage, endangering the life of the fetus. Early diagnosis and timely treatment should be carried out.

　　What are the symptoms of fetal distress? Briefly described as follows:

　　1. Maternal weight, fundal height, and abdominal circumference

　　It continues to grow slowly or grow very slowly.

　　2. Fetal movement monitoring

　　Indicating a decrease in fetal movement, especially when fetal movement is less than 4 times per hour, attention should be paid to the possibility of stillbirth in the uterus.

　　3. B-ultrasound system examination

　　The biparietal diameter, the ratio of head circumference to abdominal circumference, the length of the femur, and the amount of amniotic fluid indicate fetal growth retardation.

　　4. Fetal heart monitoring includes antenatal non-stress test (NST)

　　No acceleration response of fetal heart rate is observed during fetal movement, or there is no fetal movement, which is known as the unresponsive type. Sometimes, even spontaneous deceleration of fetal heart rate may occur, and the CST test may be positive.

　　5. Comprehensive biophysical image scoring examination

　　This is through B-ultrasound to measure fetal respiration, fetal movement, fetal tone, amniotic fluid volume, and to perform NST tests through fetal monitoring, which can be manifested as low scores.

　　6. Examination of placental function

　　Estriol, placental lactogen, and estradiol/creatinine ratio can show sustained low values or a decreasing trend.

　　7. Amnioscope examination

　　The amniotic fluid is contaminated with meconium.

　　8. Chronic fetal distress

　　This often occurs in the late stage of pregnancy and often persists until labor and worsens. The causes are often due to systemic diseases in pregnant women or diseases during pregnancy, leading to insufficient placental function or fetal factors. Clinically, in addition to finding diseases in the mother that can cause insufficient placental blood supply, with the extension of chronic fetal oxygen deficiency, fetal intrauterine growth retardation may occur.

　　9. Acute fetal distress

　　This mainly occurs during labor and is often caused by factors such as umbilical cord problems (such as prolapse, around the neck, knotting, etc.), placental abruption, strong and prolonged uterine contractions, and the mother being in a state of hypotension or shock. Clinical manifestations include changes in fetal heart rate, amniotic fluid meconium contamination, frequent fetal movements, cessation of fetal movements, and acidosis.

　　10. Changes in fetal heart rate

　　Abnormal changes in fetal heart rate are the earliest symptoms of fetal distress. The normal heart rate of the fetus is 120 to 160 beats per minute, with heart rates above 160 or below 120 considered abnormal, and below 100 beats indicating severe oxygen deficiency. During distress, the fetal heart rate initially increases, and the heartbeat is regular and strong, but then it starts to slow down, weaken, and become irregular. However, it should be noted that during uterine contractions, the fetal heart rate may slow down temporarily due to the interference in the uterine-placental blood circulation, but it quickly returns to normal after the uterine contractions stop. Therefore, the fetal heart rate between two uterine contractions should be taken as the standard.

　　11. Abnormal fetal movement

　　Fetal movement is one of the vital signs of the fetus, which can be used to understand the safety of the fetus in the uterus and is also a good method for pregnant women to self-monitor, with a reliability of over 80%. Normally, fetal movements should not be less than 3 times per hour, and should not be less than 30 times in 12 hours. If the fetal movements suddenly increase sharply during labor, becoming frequent and strong, it indicates that the fetus may experience acute distress, often caused by factors such as umbilical cord compression, placental abruption, etc., leading to acute fetal oxygen deficiency. If the number of fetal movements on that day is reduced by 30% or more compared to the previous days, it is considered a decrease in fetal movements. Once the fetal movements cease, the fetus may die at any time, with the death time usually occurring within 12 to 72 hours after the disappearance of fetal movements.

　　12. Changes in amniotic fluid

　　When amniotic fluid is insufficient, the contracted uterine wall can directly compress the fetus and umbilical cord, leading to fetal distress. During labor, if the cervix dilates and examination shows that the amniotic sac is devoid of tension or there is no amniotic sac at all, with the fetal membrane tightly adhering to the fetal head, or only a small amount of amniotic fluid flows out after membrane rupture, even without any amniotic fluid leakage, it indicates a possible issue of insufficient amniotic fluid. Normally, amniotic fluid is a colorless and transparent liquid. When the fetus is oxygen-deprived, meconium is excreted, changing the color of the amniotic fluid. In vertex delivery, the presence of meconium along with abnormal fetal heart rate is a typical symptom of fetal distress. The degree of meconium contamination of amniotic fluid can be classified into three degrees. First-degree contamination results in pale green and thin amniotic fluid. Second-degree contamination results in green, thicker amniotic fluid, which can contaminate the fetal skin, mucous membranes, and umbilical cord, usually indicating acute fetal oxygen deficiency. Third-degree contamination is characterized by a large amount of yellow-brown meconium mixed with amniotic fluid, thick and dense, with a small amount, which is a clear sign of fetal distress. When the fetal membrane, placenta, fetal skin, and nails are stained yellow-brown, it suggests that fetal oxygen deficiency has exceeded 6 hours, and the fetus is in a critical condition.

　　Fetal intrauterine distress can directly threaten the health and life of the fetus. Therefore, regular prenatal examinations are very important, which can timely detect the occurrence of abnormal conditions in the mother or fetus, such as hypertensive diseases during pregnancy, chronic nephritis, prolonged pregnancy, placental aging, anemia, delayed fetal development, placenta previa, combined heart disease, etc., so as to determine the degree of harm to the fetus, formulate corresponding treatment plans, and prevent or treat them. Pay attention to self-care during pregnancy, increase nutrition, combine work and rest, avoid bad habits, and prevent placental abruption. If there is a feeling of discomfort or a decrease in fetal movements, seek medical attention in a timely manner. For fetal intrauterine distress that is ineffective in treatment, such as being nearly full term but not in labor, the extracorporeal environment is better than the intrauterine environment, and the pregnancy should be terminated as early as possible.

　　What examinations should be done for fetal distress? Briefly described as follows:

　　First, diagnosis of chronic fetal distress

　　1. Placental function examination. Measure the 24-hour urinary estriol (urine E3) value and observe dynamically and continuously. If it decreases sharply by 30% to 40%, or if the 24-hour urine E3 value is below 10mg in multiple measurements continuously at the end of pregnancy, it indicates a reduction in fetal and placental function.

　　2. Fetal heart monitoring. Continuously describe the fetal heart rate of the pregnant woman for 20 to 40 minutes, and the normal baseline fetal heart rate is 120 to 160 beats per minute. If the fetal heart rate does not accelerate significantly during fetal movement, the baseline variability rate

　　3. Counting fetal movements. When the pregnancy is nearly full term, fetal movements > 20 times per 24 hours. The calculation method can be to ask the pregnant woman to monitor the number of fetal movements for 1 hour in the morning, afternoon, and evening, and then multiply the sum of the three times by 4, which is the approximate number of fetal movements in 12 hours. A decrease in fetal movements is an important indicator of fetal distress, and monitoring fetal movements daily can predict the safety of the fetus. After the disappearance of fetal movements, the fetal heart rate will also disappear within 24 hours, so attention should be paid to this to avoid missing the opportunity for rescue. Excessive fetal movements are often the precursor symptoms of the disappearance of fetal movements and should also be paid attention to.

　　4. Amnioscope examination. The amniotic fluid appears turbid and yellowish to dark brown, which is helpful for the diagnosis of fetal distress.

　　Second, diagnosis of acute fetal distress

　　1. Changes in fetal heart rate. Fetal heart rate is an important indicator to understand whether the fetus is normal:

　　(1) Fetal heart rate > 160 beats per minute, especially > 180 beats per minute, is an early sign of fetal hypoxia (in cases where the mother's heart rate is not fast);

　　(2) Fetal heart rate

　　(3) Late deceleration of fetal heart rate, variable deceleration, or (and) lack of variability in the baseline all indicate fetal distress. When fetal heart rate is abnormal, a detailed examination of the cause is required. Changes in fetal heart rate cannot be determined solely by a single auscultation; multiple checks and changing the position to lateral recumbency should be done before continuing to check for several minutes.

　　2. Amniotic fluid meconium contamination. Fetal hypoxia causes vagal nerve excitement, increased peristalsis, and relaxation of the anal sphincter, causing meconium to be excreted into the amniotic fluid, making the amniotic fluid green, yellow-green, and eventually turbid brown, indicating the first, second, and third degrees of amniotic fluid contamination.

　　3. Fetal movement. In the early stage of acute fetal distress, it first manifests as frequent fetal movements, then weakens and decreases in frequency, and eventually disappears.

　　4. Acidosis. After amniotic membrane rupture, blood gas analysis should be performed on the fetal scalp blood for analysis.

　　During the entire pregnancy, the mother's body weight should increase by 9 to 15 kilograms, so the intake of food for pregnant women should be increased by 10% to 20% compared to ordinary times. For nausea and vomiting caused by early pregnancy reactions, it is recommended to eat small and frequent meals, and the diet should be light and easy to digest. Some sour fruits such as jujube and tangerine can be eaten, but preserved vegetables should not be eaten.

　　The following methods are introduced for the treatment of fetal distress:

　　First, Chronic Fetal Distress

　　Treatment should be determined based on the cause, gestational age, fetal maturity, and severity of distress.

　　1. Those who can regularly undergo prenatal examinations are estimated to have a good fetal condition and should rest more on their sides to improve placental blood supply and extend the gestational weeks.

　　2. The situation is difficult to improve, approaching term pregnancy, and if the fetus has a high chance of survival after delivery, cesarean section can be considered.

　　3. The farther away from term pregnancy, the lower the survival possibility of the fetus after delivery, and the situation should be explained to the family, and conservative treatment should be tried to extend the gestational weeks. In cases where the fetal and placental function is poor, the fetal development will inevitably be affected, so the prognosis is poor.

　　Second, Acute Fetal Distress

　　2. When the cervix is fully dilated and the presenting part of the fetus has reached 3 cm below the ischial spines, the fetus should be delivered as soon as possible through vaginal delivery.

　　1. The cervix has not fully dilated, and the condition of fetal distress is not severe. Oxygen can be administered (face mask oxygen supply) to improve the oxygen supply to the fetus by increasing the oxygen content in the maternal blood. At the same time, instruct the mother to lie on her left side and observe for 10 minutes. If the fetal heart rate returns to normal, continue to observe. If the fetal heart rate slows abnormally due to the use of oxytocin and strong uterine contractions, stop the infusion immediately and continue to observe whether it can return to normal. In urgent conditions or if the above treatment is ineffective, an immediate cesarean section should be performed to end labor.