Late Onset Growth Restriction


Late Onset Growth Restriction, Asymmetric IUGR, Asymmetric Intrauterine Growth Retardation

  • Epidemiology
  1. Represents 70-80% of cases of Intrauterine Growth Restriction
  • Background
  1. Late onset Fetal Growth Retardation has onset >32 weeks gestation
  2. Typically results from utero-placental insufficiency (see causes below)
  3. Previously described as Asymmetric Intrauterine Growth Retardation
    1. However, timing of onset (early or late) is more predictive of complication than asymmetry
    2. Intrauterine Growth Retardation with head sparing
    3. Severe Asymmetric IUGR may become Symmetric IUGR
    4. Associated with chronic Fetal Hypoxia
  4. Less severe than Early Onset IUGR
    1. Abnormal umbilical artery in <10%
    2. Rare perinatal death
  • Associated Conditions
  1. Preeclampsia in 12% of cases (greater association with Early Onset IUGR)
  • Causes
  • Utero-Placental Insufficiency
  1. See Intrauterine Growth Retardation
  2. Maternal Preeclampsia or Chronic Hypertension
  3. Gestational Diabetes (Second most common cause IUGR)
  4. Maternal Collagen Vascular Disease
  5. Maternal Tobacco Abuse
    1. Most common preventable cause of IUGR
    2. Birth weight reduced 200 grams if mother smokes
  6. Maternal Infection
  • Complications
  1. Fewer neurologic complications than Early Onset IUGR
  2. Perinatal complications
    1. Polycythemia (hyperviscosity)
    2. Hypoglycemia