20 week scan

They’re all the measurements they’ve taken like head circumference etc x

makes sense. And the scale? How do I understand that?

I don't think I have as many as yours but maybe this will give you an idea what some are:

I think it’s the range for the age like for example CM is between 2mm and 10mm at 20 weeks xx i just google everything as i dont understands anything either haha x

If you don’t have Chat GPT id recommend getting it as I just put any questions into there and it’s really useful much better than Google x

Urgh sorry I am struggling with uploading photo so Hc 163.2mm= head circumference. Tcd = transcerebellar diameter. Ac = abdominal circumference. FL 29.8mm= I think is femur length?

Yes these are the measurements taken of baby, they measure parts individually & in different combinations to assess so that’s why there are so many. The mm is the measurement. The graph plots this measurement and these are referred to as percentiles. The middle marker indicates bang on average. They take your babies measurements and compare them to the average from data collated for that number of weeks/days. Remember every baby is unique and some smaller/bigger based on genetics etc. and the measurements have a margin or error too so not to be taken too literally. And they change depending on the week/baby size. Anyways they are only concerned if percentiles are extreme low or high or fall outside of the bar. They have to tell you if any concern. I’ve had small head measurements (5th centile) with my girl and so had to have more scans but all fine and she was born with a normal head. Your baby’s graph looks very normal and between 25-60th centiles depending on the measurement.

The image shows biometric measurements from a 20-week pregnancy ultrasound. Key fetal growth indicators include:

BPD (Head Width): 45.3 mm

OFD (Head Length): 58.6 mm

HC (Head Circumference): 163.2 mm

CM (Cisterna Magna): 6.0 mm (part of brain assessment)

TCD (Cerebellum Width): 19.3 mm

TAD (Chest/Abdomen Width): 45.8 mm

APAD (Abdomen Depth): 48.3 mm

AC (Abdomen Circumference): 147.8 mm

FL (Femur Length): 29.8 mm


These measurements appear within the normal range for 20 weeks, as indicated by the red dots on the reference scale. For detailed interpretation, consult your doctor.

If you don’t understand them your midwife should go through them with you at your next appointment or even the sonographer if you ask and they have time x