Ultrasound dating scan

An average length of the embryo at 7 weeks is anywhere between 5mm-12mm. Obviously, every pregnancy is unique and individual factors influence the size of the embryo at this early stage, and the embryo shows development week by week.

Crown/rump length and gestational age are closely compared with each other until around the end of the first trimester.

Generally, ultrasounds which are performed in the first trimester are within 3-5 days of being accurate in terms of assessing gestational age.

This is because although every little embryo is unique, there are still defining characteristics of development which apply to all embryos at particular stages of early gestational development.

From this measurement we can work out how many weeks and days preganant you are (this early measurement is approximate for dating).

If a fetal heartbeat is present the risk for miscarriage at this stage is reduced to approximately 5%.

– At this stage the baby is now much more recognisable as a developing baby.

If the heartbeat is present and the baby measure appropriately for your dates, the risk for having a miscarriage now drops to 1%.

Please call the Practice on 01 to book your appointment.

At around seven weeks of pregnancy, it’s reasonably common for women to have their first ultrasound.

– At this stage the pregnancy is of course small, but we should be able to see the gestation sac with a yolk sac developing in your uterus.

We should be able to see and hear your baby’s heartbeat on scan, which is very reassuring.

If we cannot see a heartbeat then this is either due to the pregnancy being too early (this is the commonest reason) or that the pregnancy is found to be not viable.