This ultrasound scan is usually carried at about 28-36 weks of pregnancy and aims at determining the growth and health of the fetus. 

This scan aims to determine the growth and health of the fetus by:

• Measurement of the size of the fetal head, abdomen and thigh bone and calculation of an estimated fetal weight
• Examination of the movements of the fetus
• Evaluation of the placental position and appearance
• Measurement of the amount of amniotic fluid
• Assessment of blood flow to the placenta and fetus by colour Doppler ultrasound

A pathological decrease in the rate of fetal growth and blood flow defines Fetal Growth Restriction. There may be various causes of this fetal growth restriction which need to be figured out by a fetal medicine expert.

Obstetric Doppler is the study of the blood flows to the fetus.