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» Scarleteen Boards: 2000 - 2014 (Archive) » EXPERT ADVICE » Ask Scarleteen » even the early tests don't work that early....

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Author Topic: even the early tests don't work that early....
she_who_questions
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I have a pretty basic question about early pregnancy tests. On the Scarleteen website, it says that a pregnancy test will be effective 10-14 days after the risk. However, on the package for First Response Early Pregnancy tests, it indicates that a test will be accurate as early as 5 days before a missed period. This is causing some confusion with me. For example, if I were to test ten days after my most recent risk, it wouldn't yet be five days before my missed period. Why the discrepancy, and which rule should I follow? Thanks.
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KittenGoddess
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Peeing on a Stick: All About Pregnancy Tests Take a look at the last sidebar box on that article.

The gist of it is that the company producing the test makes two assumptions. First, they assume that every woman has the traditional "average" cycle, meaning right around 28 days, and that you ovulate around midcycle (which would be around day 14). Secondly, they assume that you had unprotected sex around the time when you would ovulate.

So, let's do the math both ways with that assumption in mind.

If you test 10 days after your risk (which we're assuming was around day 14 of your 28 day cycle), that would make you testing on day 24.

If we count backward from your expected period on day 28...we come up with day 23.

Basically the same thing give or take a day.

What all this adds up to mean is that the test should be sensitive enough to detect a pregnancy within about 10-14 days of your risk because they've designed it based on the 28 day assumption...even if you don't have that 28 day cycle it will still be true for you. It's designed to detect around the amount of hCG that would be in your body around 10-14 days after. Since conception does not happen immediately, the further from your risk you are the more likely you will get an accurate result.

Does that make sense?

[ 06-18-2009, 07:02 PM: Message edited by: KittenGoddess ]

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Sarah Liz

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she_who_questions
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Thanks! Yea, it makes sense. Kind of a weird assumption for the company to make though.
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KittenGoddess
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Unfortunately, a lot of people, women included assume that everybody has a 28 day cycle and ovulates on day 14. While it is true that many women have that cycle, it's not for everybody. The only way to actually know when you ovulate is to chart basal temps and cervical mucus.

So the assumptions are kind of based on the "average"...and thus they provide instructions for that case. The sensitivity of the test itself does not change and is going to be the same regardless of when you ovulated or how long your cycle is.

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Sarah Liz

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