Pregnancy dating scans how accurate dating a house
And your periods may have been pretty irregular prior to conception.
In such cases, a scan at the earliest opportunity will give a clue as to the potential delivery date.
Subsequent scans done further into the second and third trimester have increasing margins of error, and can be erroneous by a factor of weeks.
ALSO READ: Safe exercises to close your belly gap after pregnancy The due date should be agreed on pretty early in the pregnancy, preferably by a first trimester dating scan.
You should then come up with the best estimate which you should stick to.
Any other suggested dates, especially if based on scans done in advanced pregnancy, can just be ignored.
It is immediately obvious then that women with irregular periods may have erroneously calculated EDDs.
The more precise method of calculating the EDD is based on ultrasound computations.
It is important to have an estimated date of delivery from the outset.
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I have had several scans in my now advanced pregnancy, and each gives me a different estimated due date.
The next best estimate is using the first date of your last period, if this is known accurately and on a background of regular cycles.
So the question of varying the due date with every other scan should hardly arise.