HOW TO MANAGE INTRAUTERINE GROWTH RESTRICTION | DON STEVE BLOG
March 29, 2024

Intrauterine growth restriction (IUGR) refers to a condition in which a fetus does not achieve its expected growth potential while still in the womb. It is characterized by the inability of the fetus to reach its genetically predetermined size and weight for a given gestational age. IUGR can occur due to various factors that impair the normal growth and development of the fetus.

The condition is typically diagnosed when the estimated fetal weight falls below the 10th percentile for a particular gestational age or when the rate of fetal growth is significantly slower than expected. IUGR can affect both the overall size of the fetus and the development of individual organs and tissues. It is important to note that IUGR is different from small-for-gestational-age (SGA) infants, as the latter refers to infants who are smaller than average but have achieved their growth potential.

IUGR can have multiple causes, including maternal factors such as chronic hypertension, preeclampsia, chronic kidney disease, or malnutrition. Placental abnormalities, such as placental insufficiency or placental abruption, can also contribute to IUGR. Other factors that may contribute to the condition include maternal smoking, drug use, multiple pregnancies (e.g., twins or triplets), certain infections, and genetic factors.

The consequences of IUGR can vary depending on the severity and underlying causes. In some cases, infants with IUGR may experience complications such as low birth weight, difficulty maintaining body temperature, hypoglycemia (low blood sugar), respiratory problems, and an increased risk of infections. They may also have long-term health issues, including developmental delays, learning difficulties, and an increased risk of chronic diseases later in life.

Timely diagnosis and appropriate management of IUGR are crucial to optimize outcomes for both the fetus and the mother. Monitoring fetal growth through ultrasound examinations and other diagnostic tests, along with managing any underlying maternal conditions, are important aspects of managing IUGR. In some cases, delivery may need to be induced earlier than expected to ensure the well-being of the fetus.

 

Types of intrauterine growth restriction

There are two main types of intrauterine growth restriction:

  1. Symmetrical IUGR: In this type, all parts of the fetus are proportionally affected, resulting in a reduced overall size. The head, abdomen, and long bones are all smaller than expected for the gestational age. Symmetrical IUGR is often associated with genetic abnormalities, congenital infections, or exposure to certain toxins.
  2. Asymmetrical IUGR: Also known as selective or disproportionate IUGR, this type primarily affects the fetus’s body weight while sparing the head and brain growth. Asymmetrical IUGR usually occurs in the later stages of pregnancy. It is commonly caused by inadequate blood flow to the uterus and placenta, resulting from conditions such as maternal hypertension, placental insufficiency, preeclampsia, or chronic maternal illnesses.

It’s important to note that these types of IUGR may overlap or coexist in some cases. The diagnosis and management of IUGR should be done by a healthcare professional, such as an obstetrician or a perinatologist, who can assess the specific circumstances and provide appropriate care.

 

IUGR Risk Factors

Several risk factors have been identified that may contribute to the development of IUGR. Here are some common risk factors:

  1. Maternal factors:
    • Chronic medical conditions such as high blood pressure, diabetes, kidney disease, or heart disease
    • Maternal malnutrition or poor maternal weight gain during pregnancy
    • Maternal smoking, alcohol consumption, or illicit drug use
    • Infections during pregnancy, such as urinary tract infections, sexually transmitted infections, or systemic infections
    • Multiple pregnancies (twins, triplets, etc.)
    • Maternal age (very young or advanced maternal age)
  2. Placental factors:
    • Placental abnormalities or malformations
    • Placental insufficiency, where the placenta fails to provide adequate oxygen and nutrients to the fetus
    • Placental abruption, where the placenta separates from the uterine wall prematurely
  3. Fetal factors:
    • Genetic abnormalities or chromosomal disorders
    • Fetal infections, such as cytomegalovirus (CMV), toxoplasmosis, or rubella
    • Congenital malformations or birth defects
    • Fetal anemia or blood disorders
    • Reduced amniotic fluid levels (oligohydramnios)
  4. Environmental factors:
    • Exposure to environmental toxins or pollutants
    • Maternal stress or psychological factors
    • Low socioeconomic status or inadequate access to healthcare

It’s important to note that having one or more risk factors does not necessarily mean that a woman will develop IUGR. However, these factors increase the likelihood of its occurrence. If you have concerns about IUGR or any pregnancy-related issues, it’s best to consult with a healthcare professional for proper evaluation and guidance.

 

IUGR Fetal Complications

IUGR can lead to several fetal complications, which I will describe below:

  1. Low birth weight: One of the primary consequences of IUGR is low birth weight. The baby is significantly smaller than expected for its gestational age, often weighing less than the 10th percentile for that age. Low birth weight increases the risk of various health problems in newborns.
  2. Nutritional deficiencies: Inadequate nutrient supply due to placental insufficiency can result in nutritional deficiencies for the developing fetus. This can affect the baby’s overall growth, organ development, and functionality.
  3. Organ dysfunction: IUGR babies are at a higher risk of organ dysfunction due to their compromised growth and development. Organs such as the lungs, heart, liver, and kidneys may not develop properly, leading to long-term health issues.
  4. Hypoxia: In severe cases of IUGR, the compromised blood flow and nutrient supply to the fetus can result in chronic or intermittent oxygen deprivation (hypoxia). This lack of oxygen can lead to brain damage, affecting the baby’s neurological development and potentially causing cognitive and motor impairments.
  5. Meconium aspiration: In some instances, IUGR babies may pass meconium (a baby’s first stool) while still in the womb due to fetal stress. The baby may inhale or aspirate the meconium-stained amniotic fluid, leading to respiratory complications after birth.
  6. Increased risk of stillbirth: IUGR increases the risk of stillbirth, particularly in severe cases where the compromised growth and development of the fetus become life-threatening. This emphasizes the importance of close monitoring and timely intervention in IUGR pregnancies.
  7. Long-term health issues: IUGR babies may be at an increased risk of developing long-term health problems later in life. These may include cardiovascular diseases, hypertension, metabolic disorders (such as diabetes), and neurodevelopmental issues.

It is important to note that not all IUGR babies will experience the same complications, and the severity of complications can vary depending on the underlying cause and the degree of growth restriction. Early detection, proper management, and close monitoring throughout pregnancy can help mitigate some of these complications and improve outcomes for IUGR babies. Obstetricians and perinatologists work closely with parents to provide appropriate care and interventions based on the specific circumstances of each case.

 

Role of CTG, ultrasound and Doppler US

It is important to manage IUGR to ensure the well-being of both the mother and the baby. In this context, various imaging techniques play a crucial role in the management of IUGR, including cardiotocography (CTG), ultrasound, and Doppler ultrasound (Doppler US).

  1. Cardiotocography (CTG): CTG is a non-invasive technique used to monitor fetal well-being by assessing fetal heart rate (FHR) and uterine contractions. In cases of IUGR, CTG can provide information about the fetal heart rate pattern, which can help identify signs of distress. CTG monitoring can be performed intermittently or continuously, depending on the severity of the IUGR and the clinical situation.
  2. Ultrasound: Ultrasound is a commonly used imaging modality in the management of IUGR. It provides detailed anatomical information about the fetus, placenta, and amniotic fluid, which helps in assessing growth and identifying potential causes of IUGR. Ultrasound can be used to estimate fetal weight, measure fetal biometric parameters (such as head circumference, abdominal circumference, and femur length), and assess amniotic fluid volume.
  3. Doppler Ultrasound: Doppler ultrasound is a specialized technique that allows the assessment of blood flow in the fetal and maternal circulation. It measures the velocity of blood flow, which helps in evaluating the placental and fetal circulation in cases of IUGR. Doppler ultrasound can be used to assess the umbilical artery, middle cerebral artery, and uterine artery blood flow. Abnormal Doppler findings, such as increased resistance or decreased diastolic flow, may indicate placental insufficiency or compromised fetal circulation.

The role of CTG, ultrasound, and Doppler US in the management of IUGR includes:

  1. Diagnosis: Ultrasound is used to diagnose IUGR by measuring fetal size and growth parameters and comparing them to gestational age standards. It can help identify asymmetric growth patterns and detect abnormalities in the placenta or umbilical cord.
  2. Monitoring fetal well-being: CTG is utilized to monitor the fetal heart rate and assess fetal well-being during labor. It helps identify signs of fetal distress, such as non-reassuring heart rate patterns, which may necessitate interventions such as expedited delivery.
  3. Assessing placental function: Doppler ultrasound evaluates blood flow in the placenta and umbilical artery. Abnormal Doppler findings may suggest impaired placental function and inadequate oxygen and nutrient supply to the fetus.
  4. Planning interventions: CTG, ultrasound, and Doppler US findings aid in the decision-making process regarding the timing and mode of delivery. In severe cases of IUGR, early delivery may be necessary to prevent further compromise to the fetus.
  5. Follow-up monitoring: Serial ultrasounds and Doppler studies help monitor fetal growth and well-being over time. Regular assessments allow healthcare providers to make informed decisions about the timing of delivery or the need for additional interventions.

It’s important to note that the specific use and interpretation of CTG, ultrasound, and Doppler US in the management of IUGR may vary based on individual patient characteristics, gestational age, and clinical guidelines followed by healthcare providers. Consulting with a qualified healthcare professional is crucial for accurate diagnosis and appropriate management of IUGR.

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