Causes of Asymmetrical Intrauterine Growth Retardation
This is when the head circumference is less affected than the abdominal circumference.
·Idiopathic: probably due to placental failure
·Maternal hypertension with proteinuria: may also be secondary to placental insufficiency
·Severe maternal illness, including cardiac disease, particularly those causing polycythemia
·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.