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Conception Dates

If a woman's periods are not regular and she falls pregnant how accurately can one then determine the conception date from an ultrasound?


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2006-09-17 11:02:25
2006-09-17 11:02:25

For about the first 10-12 weeks all babies grow at about the same rate so term date can be calculated fairly accurately, you then count back 38 weeks for the date of conception. After 12 weeks babies may not all grow at the same rate so it becomes less accurate.

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An ultrasound will determine the date of conception by measuring the fetus. You conceived somewhere between March 23 and April 24. It is difficult to pinpoint the exact date of conception this way without an ultrasound to measure the fetus.

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Conception date is based on your last ovulation cycle prior to when you didn't get your period. But this can be incorrect if you didn't conceive when you was ovulating. Alternatively you can have a ultrasound scan which will give you a conception date but this can be off by 5 days.

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Well, that is something that an ultrasound will have to determine. The theory is that you are pregnant (conception has occurred) sometime after your last period. Conception doesn't necessarily occur the moment that the man ejaculates his sperm into the vagina. So, yes, you did become pregnant somewhere between when you had sex after your last period, but before you realized that you were late in getting your period. This has to be discovered by the ultrasound, to determine the EDD (estimated due date).

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I am guessing you mean that you want to know your date of conception? It really depends on a couple of factors. If your normal periods are regular, you can be fairly accurate with conception date within a couple of days. Count back 14 days from when your period was DUE (ie but didn't come because you were pregnant) and this will be around the time of conception. Conception date will be within two days either side of this date. If you are pregnant now, an ultrasound will tell you very accurately what your conception date is. As long as you have an ultrasound within the first 10 weeks - the earlier the better. An experienced ultrasonic person can tell you down to the day - ie six weeks and three days.

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It is kind of hard to tell until you get your ultrasound. But you can Google pregnancy calculators and it can help you determine the date of conception by entering in some information (such as when your last period was, possible days of intercourse etc.)


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