Fetal hypoxia: causes, forms, diagnosis and therapeutic approaches

Fetal hypoxia is a dangerous state of oxygen deprivation that can occur during pregnancy or delivery due to various maternal, placental, or fetal factors and requires rapid diagnosis and treatment to prevent severe health consequences for the child.

What is fetal hypoxia?

Fetal hypoxia is a pathological condition in which the developing fetus in the uterus suffers from a lack of oxygen. It can occur at any stage of pregnancy or during delivery and poses a serious danger to the health and life of the baby. Hypoxia is classified based on its duration, characteristics, and mechanisms of development.

Forms of hypoxia

Acute hypoxia

Acute hypoxia develops suddenly, mainly during delivery.

Causes: nuchal cord, placental abruption, low uterine activity, umbilical cord prolapse, maternal hypotension. This condition is dangerous due to the rapid impact on the brain and internal organs of the fetus and requires emergency intervention, most often a cesarean section.

Chronic hypoxia

It gradually appears over weeks or months, most often due to a disturbance in the placental blood supply. It may be accompanied by intrauterine growth restriction (IUGR), decreased fetal activity, and can be detected during routine examinations (ultrasound, cardiotocography — CTG, dopplerometry).

Combined hypoxia

Combines signs of both acute and chronic forms. For example, a fetus suffering from chronic hypoxia may experience an acute umbilical cord compression during delivery. It requires constant monitoring of the mother's and child's condition.

According to the time of onset

• Pre-natal — before the start of labor.
• Intra-natal: during delivery.
• Post-natal: appears after birth and is generally associated with pre-existing intrauterine hypoxia.

Causes of hypoxia

Hypoxia can be caused by many factors related to maternal health, placental condition, umbilical cord specifics, or the fetus's own state.

On the maternal side

• Anemia
• Cardiovascular diseases
• Chronic respiratory illnesses
• Infections (toxoplasmosis, cytomegalovirus, etc.)
• Hypertension, preeclampsia
• Alcohol consumption, drug use, smoking
• Metabolic disorders (e.g., diabetes)

On the placental side

• Problems with placental blood flow
• Premature aging or placental abruption
• Infarcts and tumors of the placenta (e.g., chorionic adenoma)

On the umbilical cord side

• Umbilical cord wrapping
• True knots or false knots of the cord
• Umbilical cord prolapse
• Abnormal length or attachment

On the fetal side

• Congenital malformations of the heart, lungs
• Genetic and chromosomal abnormalities
• Intrauterine infections
• Rh incompatibility
• Developmental delay

Obstetric complications

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• Multiple pregnancy
• Prolonged or induced labor, complications during anesthesia

It is important to note that hypoxia rarely has a single cause. It is most often the result of the interaction of multiple factors, making pregnancy monitoring particularly important.

Symptoms of hypoxia

Signs observed by the woman

• Increase in fetal activity, followed by a sudden decrease or complete absence of movements.
• The normal range is 10 to 15 fetal movements within 12 hours from the 28th week onwards.

Symptoms diagnosed by the doctor

• ECG : tachycardia (> 160 beats/min), bradycardia (< 110 beats/min), absence of fetal heart rate variability
• Ultrasound and Dopplerometry : fetal growth restriction, disturbed blood circulation in the cord and uterine vessels, changes in amniotic fluid volume
• Amniotic fluid analysis : presence of meconium — sign of acute hypoxia
• At birth : low Apgar score, weak cry, cyanosis (blue coloration of the skin)

In case of suspected decreased fetal activity, immediate consultation with a healthcare professional is essential.

Treatment of hypoxia

In case of chronic hypoxia

• Hospitalization
• Medications: iron preparations, antihypertensives, and hormones depending on the diagnosis
• Balanced diet
• Rest or bed rest
• Constant monitoring: ECG, ultrasound, Doppler
• If condition worsens — premature delivery (most often by cesarean section)

In case of acute hypoxia

• Emergency delivery
• Neonatal resuscitation: oxygenation, mechanical ventilation, cardiac support, neonatal intensive care

Consequences of hypoxia

• Hypoxic-ischemic encephalopathy
• Hearing, vision, and motor function disorders
• Psychomotor developmental delay
• Respiratory and cardiac problems
• In severe cases: fetal death in utero

Particularities of hypoxia during pregnancy after IVF

Fetal hypoxia after in vitro fertilization (IVF), including programs with egg donation or double donation, requires special attention. It has been established that these pregnancies have a higher risk of complications, including hypoxia.

Risk factors after IVF:

• Maternal age
• Use of donor material
• Feto-placental insufficiency
• Multiple pregnancy

After such a egg donation IVF, the risk of placental blood circulation disorders is increased, especially in women with ovarian insufficiency. Double donation may be associated with immunological complications, increasing the risk of preeclampsia and hypoxia.

These pregnancies require close monitoring, including regular ultrasounds, cardiotocographic monitoring, Doppler examinations, and hospitalization if necessary.

Prevention of hypoxia

Before pregnancy

• Consultation and examination with an obstetrician
• Treatment of chronic diseases
• Abandonment of bad habits
• Balanced diet
• Physical activity

During pregnancy

• Monitoring of fetal activity
• Following the doctor's recommendations
• prenatal screening (ECG, ultrasound, Doppler)
• Hospitalization in case of risk of fetal-placental insufficiency

Regular monitoring and timely measures significantly reduce the risk of hypoxia and its consequences for the fetus.