Third Trimester Ultrasound Scan
Fetal Growth and Wellbeing
The purpose of this examination is to assess:
- Position of the baby
- Size of the baby
- Amount of fluid surrounding the baby
- Placental resistance to blood flow
- Baby’s current state of health
Most babies are head down towards the end of pregnancy. Occasionally the baby can be in abreech position, where the bottom is closest to the cervix (opening to the uterus).The age of the baby is established in early pregnancy. The size of the baby can be compared with the size expected for this stage of pregnancy, giving information about the baby’s growth. An estimate of the weight can be calculated from the measurements.
Graph of average fetal weight range
The resistance to blood flow in the placenta is assessed with Doppler ultrasound of the umbilical artery.