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IUGR: Causes, Symptoms, Treatments, and Prevention

Intrauterine Growth Restriction (IUGR) (a.k.a: Fetal Growth Restriction) is a common pregnancy complication. It is the third leading cause of perinatal mortality. It is a condition in which the growth of the fetus is slow. If the fetal weight is below 10th percentile for its gestational age, then the condition is said to be IUGR. Due to various factors, the fetus doesn’t attain full growth potential as expected.

Intrauterine Growth Restriction

Classification of IUGR based on characteristics:

Symmetrical IUGR (Hypoplastic small for date)
Asymmetrical IUGR (Malnourished babies)
   20 to 30% of cases 70 to 80 % of cases
Occurs during earlier gestational period.  Occurs during later gestation period
  Fetal cell number gets reduced (decreased growth potential)Fetal cell number is normal (growth arrest occurs)
Cell size remains normal Cell size gets reduced
Brain symmetrical to the body of the fetusNormal size head and brain but with small body
Causes: chromosoma; disorder and intrauterine infectionsCauses: preeclampsia, hypertension, and malnutrition

What Causes IUGR?

The causes of IUGR can be categorized into fetal, maternal, and placental.  IUGR can occur due to one or more of the following causes:

  • Maternal Causes:

    • Chronic morbidities such as hypertension, diabetes, heart disease, obesity, and kidney diseases (also lead to premature birth)
    • Smoking (active or passive)
    • Alcohol (cross placental barrier and affect fetal growth)
    • Severe anemia (iron deficiency) and malnutrition
    • Addiction to drugs such as cocaine (cause vasoconstriction and affect maternal circulation)
    • Thrombophilia
    • Low pregnancy weight
    • Oligohydramnios (deficiency of amniotic fluid)
    • Use of medications such as anticoagulants (especially warfarin) or anticonvulsants
    • Teenage pregnancy
    • Uterine tract abnormalities
    • Poor socioeconomic status
  • Placental Causes:

    • Abnormal placental implantation
    • Bilobed placenta (placenta separated with two equal sized lobes)
    • Placental infarcts ( interrupted blood supply to a part of placenta)
    • Single umbilical artery (an umbilical abnormality)
    • Placental tumors or hemangiomas
    • Placental abruption (separation of placenta from the walls of the uterus)
    • Circumvallate placenta (an abnormality in the structure of the placenta)

Symptoms of IUGR:

Poor maternal weight gain and less or no fetal movements may indicate IUGR. Symptoms present in infants having IUGR are:

  • Absence of buccal fat or fat in the cheeks
  • Poor muscle mass and subcutaneous fat
  • Small abdomen
  • Long fingernails
  • Large head

Risk Factors of IUGR:

IUGR can occur due to many risk factors. Some of the main risk factors that contribute to IUGR are mentioned below:

  • Maternal age less than 17years and more than 35 years
  • Genetic factors
  • Multiple pregnancies
  • History of IUGR in previous pregnancies
  • Short interval between pregnancies
  • Malnutrition
  • Short Stature
  • Antiphospholipid syndrome
  • Smoking
  • Alcohol consumption
  • Drug abuse
  • Comorbidities such as obesity, hypertension, and diabetes

Complications of IUGR:

Due to IUGR, there is an increased risk of cesarean section. There can be fetal or neonatal complications also, such as:

  • Stillbirth (death of the infant in the womb)
  • Hypoxia or acidosis in the fetus (oxygen deficiency)
  • Congenital anomalies
  • Intellectual disability
  • Mental retardation
  • Seizures
  • Short lifespan

Diagnosis of IUGR:

IUGR is suspected in pregnant women who have a previous history of IUGR and having one or more risk factors. It can be diagnosed by performing the following tests:

Uterine Fundal Height:

It is estimated by measuring the length of mother’s belly from the pubic bone to top of the uterus.  If a woman is 27 weeks pregnant, the uterine fundal height should be around 27 cm. A lag in fundal height of 4 cm or more indicate IUGR. This measurement helps to estimate fetal growth. It is usually performed after 20 weeks.

However, it can’t be accurate if the mother is obese or carrying more than one baby. Further tests can be performed for definitive diagnosis.

Ultrasonography:

It is the reliable test for determining IUGR. During this procedure, high frequency sound waves are used to image fetal development. This test can help to measure:

  • Amniotic Fluid Index (AFI): It is the estimate of amniotic fluid volume in the fetus. If AFI is ≤ 5, it indicates severe IUGR.
  • Ponderal Index: It is the ratio of height to weight measured to determine fetal growth. Ponderal index is more than 2 in symmetrical IUGR and less than 2 in asymmetrical IUGR.
  • Abdominal circumference (AC), head circumference (HC), femur length (FL), biparietal diameter (BPD), and estimated fetal weight (EFW) are also measured in ultrasonography procedure.

Doppler Ultrasound:

This test can help to evaluate blood flow in the umbilical cord and blood vessels in the brain of the fetus.

Treatments for IUGR:

There is no specific treatment available for IUGR. However, monitoring the patient regularly and delivering promptly can result in best outcome.

Taking bed rest may improve blood flow to the uterus. Medications can also be given to improving blood flow. Hospitalization may be required in severe cases of IUGR.

If there are other causes for IUGR such as low AFI(amniotic fluid index) or if the fetal growth cannot be improved, vaginal delivery through induction or C-section can be performed at 32 to 34 weeks of gestation.

Prevention of IUGR:

Early identification of risk factors and taking necessary precautions can prevent IUGR. Measures that can help in preventing IUGR are:

  • Consume balanced diet.
  • Maintain a healthy lifestyle. Quit smoking, drugs, and alcohol consumption.
  • Take plenty of rest.
  • Take medications as prescribed. Don’t take any medications without a doctor’s advice. Treatments can be given are:
    • Vitamin and mineral supplements.
    • Therapy for comorbid conditions.
    • Aspirin can be given at 17 weeks for patients with previous history of IUGR.
  • Get vaccinated against infectious diseases.

FAQs

  1. Does caffeine cause intrauterine growth restriction?

Though caffeine can cross placental barrier, it doesn’t cause intrauterine growth restriction.

  1. When is intrauterine growth restriction detected?

It is usually detected in the third trimester of pregnancy

  1. Can uterine growth restriction cause preterm labor?

Babies can be born at term (at 37 weeks) in mild to moderate IUGR whereas preterm labor or premature birth may occur in severe cases of IUGR.

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