Ultrasound scanning of a fetus shows asymmetric growth retardation. It may be associated with the following pathology:

Asymmetric intrauterine growth retardation (IUGR) is seen in chronic placental insufficiency due to inadequate substrate transfer. The fetus is affected in later months during the phase of cellular hyperophy. The placental pathology includes, Placenta prae Abruption Circumvallate Infarction Mosaicism Poor placentation Symmetric IUGR is seen in genetic disease or infection. The fetus is affected from the noxious effect very early in the phase of cellular hyperplasia. Ref: Textbook of Obstetrics by DC Dutta, 6th edition, Page 463-464.