At around seven weeks of pregnancy, it’s reasonably common for women to have their first ultrasound.This can be for many reasons but the most common is to confirm pregnancy and to check that the embryo is viable and “everything’s ok”.A duration of only a week can make a significant difference in terms of what can and can’t be seen.At seven weeks of gestation it is still too early to identify what gender (sex) the baby will be.There are two ways of having a seven week ultrasound.One is via the abdomen – transabdominally and the other is through the vagina – transvaginally.The limbs and the yolk sac, though obviously important, are not the primary means of measuring growth.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.
With maturity, the size of the baby correlates less to its age than in the early weeks.
In very early pregnancy, the embryo and pregnancy sac may simply be too small to see very much at all.
But with every day which passes, the embryo becomes bigger and more advanced in its development.
This ten day “window” of days either side of the estimated date of confinement – the, is considered standard practice. Even with the best technology and most proficient sonographers available, ultrasounds do not provide absolute proof of dates, gender, size or the unborn baby’s status.
This applies at whatever stage of gestation the ultrasound is done.