Can 12 week dating scan wrong

When an ultrasound is performed, measurements of the head, abdomen, thigh, and amount of amniotic fluid are done.

These measurements are computed automatically in the ultrasound machine’s software.

Older women are more at risk of having a baby with Down Syndrome.

When a woman is 12 weeks pregnant her risk of having a baby with Down Syndrome can be fairly accurately assessed.

When a foetus has Down syndrome they tend to have more fluid at the base of their neck, in the region known as the nuchal fold area.

This fluid can be measured in a test called nuchal translucency.

Before the scan you will be asked to drink a lot of water and have a full bladder, as this puts the uterus in a better position to be scanned.

This can be something of an uncomfortable challenge if your sonographer has particularly long waiting times.It’s time to clap your eyes on that baby for the first time and it’s the most exciting pregnancy milestone yet. Your 12-week scan can take place any time between 11 and 13 weeks.It’s amazing to think that at this point, your baby is fully formed.The software has certain measurement scales based on data from large populations, and your baby’s measurements are put into this scale.In other words, by comparing your baby’s measurements to the data from this large collection of measurements, the ultrasound can then tell how far along your baby is.Even when the last period is known, ultrasound is reassuring to demonstrate adequate growth, especially when there’s a risk of delayed growth, as in hypertension or smoking, or if there’s the risk of exaggerated growth, as in gestational diabetes.

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