This is when the head circumference is less affected than the abdominal circumference.

 

·         Idiopathic: probably due to placental failure

·         Placental failure

·         Maternal hypertension with proteinuria: may also be secondary to placental insufficiency

·         Severe maternal illness, including cardiac disease, particularly those causing polycythemia

·         Multiple gestation

·         Causes of symmetric IUGR: most of the causes of symmetric IUGR may also cause asymmetric IUGR.

 

NB- Asymmetric  IUGR results from an attempt to protect vital structures at the expense of less critical organs. Of small for gestational age babies, 80% have no known risk factors. Only 50% of cases are detected by clinical examination. IUGR is a significant cause of morbidity and mortality in the first year of life.

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