Fetal Hypoxia - Symptoms, Signs During Pregnancy, Consequences

2024 Author: Rachel Wainwright | [email protected]. Last modified: 2023-12-15 07:39

Fetal hypoxia

The content of the article:

1. Causes and risk factors
2. Forms
3. Symptoms of fetal hypoxia
4. Diagnostics
5. Treatment
6. Forecast
7. Possible complications and consequences of fetal hypoxia
8. Prevention

Fetal hypoxia is an intrauterine syndrome characterized by multiple disorders of the internal organs and systems caused by oxygen starvation of the fetus. Perinatal hypoxia is one of the most common obstetric pathologies in Russia: up to 10.5% of newborns suffer from one or another manifestation of oxygen starvation.

Source: mamitips.com

Causes and risk factors

Fetal hypoxia is a manifestation of various pathological processes in the body of the mother or the unborn child. The risk group includes women suffering from anemia and diabetes mellitus, severe forms of preeclampsia, acute and chronic diseases of the respiratory and cardiovascular systems. Contact with toxic substances, living in an ecologically unfavorable area, bad habits of the mother also negatively affect the placental blood circulation.

On the part of the fetus, the following factors provoke hypoxia:

• malformations and developmental anomalies;
• intrauterine infections (toxoplasmosis, herpes, chlamydia, mycoplasmosis);
• prolonged squeezing of the head during childbirth;
• hemolytic disease with Rh-conflict.

Oxygen starvation of the fetus also occurs with violations of placental blood flow associated with complications of pregnancy and childbirth:

• fetoplacental insufficiency;
• anomalies in the structure of the umbilical cord;
• repeated entanglement of the umbilical cord around the child's neck;
• overburdening;
• prolapse or pressing of the umbilical cord;
• protracted or rapid labor;
• the threat of premature birth.

Source: dobrenok.com

Forms

Depending on the duration of the course, two forms of fetal hypoxia are distinguished - acute and chronic. Acute hypoxic conditions usually develop as a result of pathological childbirth, less often during pregnancy in the case of placental abruption and uterine rupture. The rapidly increasing inhibition of the functions of vital organs poses a threat to the child's life.

Chronic fetal hypoxia during pregnancy develops over a period of time. Insufficient oxygen supply to the fetal tissues triggers a cascade of pathological processes that provoke the appearance of congenital pathologies and a general lag in the child's mental and physical development. The first reaction of the body to oxygen deficiency is the centralization and redistribution of blood flow in favor of the brain, which creates the preconditions for ischemic changes in tissues. The reactive release of vasoactive hormones of the adrenal glands in the early stages of hypoxia leads to a gradual depletion of the medulla and cortical layers and secretory insufficiency, followed by the development of bradycardia and arterial hypotension. Decreased tone of precapillaries and arterioles contributes to the expansion of peripheral vessels and the appearance of capillary circulation disorders,which are expressed in a slowdown in blood flow, an increase in blood viscosity and a decrease in the intensity of gas exchange. Violation of the trophism of the vascular walls increases the permeability of the cell walls, creating conditions for the development of hemoconcentration, hypovolemia, internal hemorrhages and tissue edema. The accumulation of under-oxidized metabolic products causes respiratory-metabolic acidosis and activates lipid peroxidation, during which toxic free radicals are released. The accumulation of under-oxidized metabolic products causes respiratory-metabolic acidosis and activates lipid peroxidation, during which toxic free radicals are released. The accumulation of under-oxidized metabolic products causes respiratory-metabolic acidosis and activates lipid peroxidation, during which toxic free radicals are released.

The severity of pathological changes in chronic perinatal hypoxia depends on the duration and intensity of oxygen deficiency, as well as on the body's adaptive capabilities. In obstetric practice, compensated, subcompensated and decompensated hypoxic states are distinguished. Compensated fetal hypoxia during pregnancy does not cause serious harm to the health of the child, but the probability of the birth of absolutely healthy children after hypoxia in the intrauterine period is estimated at 4%.

The combination of acidosis, bradycardia and hyperkalemia in subcompensated and decompensated chronic fetal hypoxia causes persistent overexcitation of the parasympathetic nervous system, suppression of enzymatic reactions, dysfunction of cell membranes and hemodynamic disorders that contribute to the development of ischemic and necrotic processes in the organs and tissues of the fetus. Starting from 6-11 weeks of pregnancy, oxygen deficiency provokes a delay in the development of the central nervous system and the blood-brain barrier, the development of vascular anomalies and heart defects. Often the adrenal glands, lungs, and intestines are affected.

Symptoms of fetal hypoxia

Acute hypoxia is characterized by a sharp change in the motor activity of the fetus, deafness of heart tones and the appearance of murmurs, arrhythmia, increased or decreased heart rate - acceleration or deceleration.

Source: uziprosto.ru

The normal fetal heart rate is 120–160 beats per minute; the heart rate is about 70 beats. Slight deviations from the norm are allowed, however, with sudden changes in heart rate, accompanied by fluctuations in blood pressure, there is reason to suspect oxygen starvation. Acceleration with movements and with an increase in the tone of the uterus, numbering at least five episodes in half an hour, and isolated episodes of deceleration is also considered the norm. Motor activity is assessed based on the number of thrusts in one series: normally, there should be at least 10 movements for two minutes.

Symptoms of chronic hypoxia of conditions appear from the fourth month of pregnancy. In the early stages, signs of fetal hypoxia are expressed in increased heart rate and motor activity, then bradycardia develops, movements slow down. Later symptoms of oxygen deficiency are detected during routine examinations during pregnancy. On ultrasound, a picture of fetal growth and development is observed; sometimes congenital anomalies of the central nervous system, heart and blood vessels, poly- or oligohydramnios are added. A biochemical analysis of the blood of a pregnant woman indicates a change in the acid-base balance and the accumulation of products of fat peroxidation; when carrying out amniocentesis in the amniotic fluid, an increased concentration of carbon dioxide, changes in the ratio of enzymes and hormones are found. The detection of meconium (original feces) in the amniotic fluid indicates intestinal ischemia, which is often observed during oxygen starvation of the fetus.

Diagnostics

The preliminary diagnosis of fetal hypoxia is traditionally based on auscultation. However, this method is not absolutely reliable. Firstly, you can make a mistake when calculating the heart rate, and secondly, it is impossible to listen to the fetal heartbeat during labor contractions.

For early recognition of perinatal hypoxia in modern obstetric practice, a biophysical profile of the fetus is made, including the following indicators:

• respiratory rate;
• the intensity of large movements;
• muscle tone;
• the volume of amniotic fluid;
• cardiotocography (CTG) - registration of fetal heartbeats using an ultrasound sensor.

For an accurate assessment of the condition of the fetus during CTG, a non-stress test is performed, which records the acceleration of the heartbeat in response to an increase in uterine tone and fetal movement. Lack of acceleration indicates a slowdown in development and depletion of the compensatory capabilities of the child's body. Phonocardiography makes it possible to recognize the entanglement of the umbilical cord by characteristic noises, excluding defects of the valve apparatus and anomalies in the structure of the myocardium. Additionally, an ECG of the mother and fetus is performed.

A routine ultrasound scan reveals pathologies of the placenta, indicating the development of acute hypoxia and the need for urgent hospitalization of a woman to maintain pregnancy. The doctor should be alerted to the lag of the fetus in development, the discrepancy between the thickness of the placenta and the timing of gestation, premature maturation and detachment of the child's place.

The study of uteroplacental blood flow is carried out by means of dopplerometry of the vessels of the uterus, placenta and umbilical cord, which makes it possible to assess the severity and probable consequences of fetal hypoxia, draw up an effective pathology correction scheme and choose the optimal method of delivery.

Laboratory tests for suspected fetal hypoxia include a biochemical analysis of the blood of pregnant women and umbilical cord blood, which is taken during cordocentesis performed under ultrasound control. To exclude fetoplacental insufficiency, presentation of umbilical cord loops, prolongation and hemolytic disease, amnioscopy and amniocentesis are prescribed - endoscopic examination of the lower pole of the ovum with amniotic fluid sampling for analysis.

Treatment

Most often, chronic fetal hypoxia is diagnosed, requiring complex treatment - etiotropic and symptomatic.

According to indications, therapeutic regimens include:

• placental blood circulation stimulants: Reopolyglyukin, Euphyllin, Curantil, Sigetin;
• means for improving microcirculation and reducing intravascular blood coagulability (active ingredients - dipyridamole, dextran, pentoxifylline; less often hemoderivative of calf blood is used);
• drugs for activating intracellular metabolism and increasing the permeability of cell membranes for oxygen (essential phospholipids, glutamic and ascorbic acid, vitamins E and B ₆, glucose solution and Alupent in glucose solution);
• means for reducing the tone of the uterus: No-shpa, Terbutalin, Brikanil, Drotaverin, Ginipral (Hexoprenaline), Papaverine;
• antihypoxants and neuroprotectors (active ingredients - amtizol, gutimine, piracetam, gamma-hydroxybutyric acid and its derivatives).

If a pregnant woman detects chronic diseases that cause fetal hypoxia, the underlying pathology is treated in parallel. In the event of fetoplacental insufficiency, a woman must observe strict bed rest. In order to prevent inferior vena cava syndrome, it is recommended to lie on the left side. For 5-8 days, a course of infusion therapy is carried out, after which they switch to taking medications orally or in the form of intramuscular injections. With positive dynamics, the patient is allowed to return to moderate activity. Shown are aqua aerobics and breathing exercises, walks in the fresh air, physiotherapy procedures - ultraviolet irradiation and inductothermy. Obstetrics for chronic fetal hypoxia is carried out using cardiac monitoring.

Acute fetal hypoxia is treated exclusively in a hospital. In order to replenish oxygen deficiency, oxygen therapy is prescribed - inhalation of pure humidified oxygen through a mask. Solutions of 10% glucose with insulin, 10% calcium gluconate, 2.4% Euphyllin and 1% Sigetin with adenosine triphosphate (ATP) and ascorbic acid with cocarboxylase are injected intravenously, additionally, a drip of 5% sodium bicarbonate solution is prescribed. With sudden onset of bradycardia, intravenous and subcutaneous injections of 0.1% atropine sulfate solution are used; in case of access to the presenting part, the drug is administered directly to the fetus.

In case of complete abruption of the placenta, the fetus dies within 2-4 hours. The only way to save a child's life is an emergency caesarean section. Also, an indication for artificial delivery is the low efficiency of conservative treatment of acute and chronic hypoxic conditions and a gestational age of 28 weeks.

Forecast

The prognosis for fetal hypoxia depends on the timing of gestation. Hypoxic conditions that have arisen in the first months of pregnancy slow down the growth rate and physical development of the fetus, as a result of which a baby born at the right time gives the impression of being premature and needs intensive care. Oxygen starvation in late gestation causes CNS abnormalities and can cause mental retardation. The worst prognosis for the survival of newborns with severe hypoxia, occurring against the background of deep multiple organ disorders.

Possible complications and consequences of fetal hypoxia

Complications of fetal hypoxia most often affect the central nervous system: cerebral edema, perinatal encephalopathy, areflexia and convulsive syndrome. From the respiratory system, pulmonary hypertension and post-hypoxic pneumopathy may develop. In the most severe cases, perinatal hypoxia is accompanied by a complex of respiratory and metabolic pathologies caused by immaturity of the lungs and insufficient production of a suffractant. In the medical literature, this condition is referred to as respiratory distress syndrome, respiratory distress syndrome, or hyaline membrane disease. According to statistics, distress syndrome is recorded in 9 newborns per thousand live births, accounting for 30 to 50% of neonatal deaths.

In case of damage to the cardiovascular system, congenital heart and vascular defects, ischemic endocardial necrosis develop. A progressive decrease in blood flow velocity and the development of acidosis provokes the onset of DIC-syndrome - a severe hemorrhagic diathesis associated with the depletion of the resources of the coagulation system. Against the background of a high toxic load on the body, renal failure and oliguria, necrotizing enterocolitis and secondary immunodeficiency develop. In 75–80% of cases, fetal hypoxia is accompanied by asphyxia.

Source: simptomer.ru

Prevention

Acute perinatal hypoxia is difficult to prevent, however, with timely completion of routine diagnostic procedures during pregnancy, there is a chance to preserve the fetus and minimize damage to the child's health. At the first signs of trouble, such as changes in fetal motor activity, abdominal pain and vaginal discharge, you should immediately consult a doctor.

The prevention of chronic oxygen deficiency is highly dependent on the behavior of the expectant mother. You should give up bad habits and convince all family members to refrain from smoking in the presence of a pregnant woman, since passive inhalation of cigarette smoke by the mother is just as dangerous for the fetus as active smoking. To enrich the blood with oxygen, it is recommended to ventilate the house more often and walk in the fresh air, avoiding visiting ecologically unfavorable areas, guarding against infections and limiting contact with toxic household chemicals. A pregnant woman's diet should have a sufficient amount of iron-containing foods; if necessary, prescribe multivitamins and iron supplements.

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Anna Kozlova Medical journalist About the author

Education: Rostov State Medical University, specialty "General Medicine".

The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!