Why the HPT accuracy chart?

brookelynpaisley · July 2010

Hopefully this isn't an overly annoying or recently discussed question, but I'm curious. We all go by the HPT accuracy chart in terms of DPO, but why do HPTs' claims to be accurate not match up? I get they have to sell the things, and selling early means more chances in a month to sell them. But why the big discrepancy between my Answer test's claims to be accurate 5 days before my missed period (typically 7DPO) and the chart's accuracy of <35% (the rate at 10DPO)?

rrcraz7 · July 2010

Marketing & because the average person doesn't know how many DPO they are

cozylittlecave · July 2010

I'd actually be interested in seeing how they make those claims too- as in the studies conducted to come to those statements (if any).

I bought some of those goofy 'work out' flip flops recently (not to burn more calories- I just thought they were really comfy). It was actually interesting reading in the little booklet about the studies they did to make those claims.

Lkat17 · July 2010

I think it has something to do with the fact that people ovulate at different times, have different length LPs, and implant at different times. So for some folks, they may be able to test at the earliest possible date and get a positive, for others the test will be inaccurate early on.

cantalopes24 · July 2010

I think its beacause 5 days before your missed period would be the earliest they could detect anything and the accuracy is because people ovulate at different points in their cycle maybe?

BalletPink81 · July 2010

I think that the wording they use in their advertisements is very clever, and most people don't pick up on what they are actually saying. They say something like "Can detect pregnancy up to 5 days before your missed period." But the fine print will tell you the accuracy of the test actually being able to detect pregnancy that early. I started paying closer attention to HPT commercials since we have started TTC.

iris427 · July 2010

I think it means that it can detect HCG at a certain level and that in some people, that would be as early as X days before your missed period. So therefore they can say that it detects pregnancy that many days sooner, even if it actually won't for a lot of people.

How is it actually worded on the test? The one I took with my daughter said "99% accurate*

*by the time of your missed period"

or something like that.

XXXXX222 · July 2010

The HPT manufacturers are going on the assumption that you have the textbook 14 day LP, so it's not that much of a discrepancy. Most women don't chart, so it's easier to explain it as "X number of days before your missed period". Also, if you're not charting, and you're unaware of when you ovulated, you're more likely to buy more test unnecessarily. This means more bucks for the HPT companies.

BalletPink81 · July 2010

They probably also use an average LP of 14 or 15 days, whereas many women (like myself) who have a 10 day LP will never get a +HPT 5 days before their missed period!

DestinedtobeDomestic · July 2010

I found this on peeonastick.com:

"some HPT's say "test 5 days before your period is due!" or some such thing. Please note they are assuming a textbook 28-day cycle, with ovulation on Day 14. "5 days before your period is due" thus really "translates" to 10 DPO."

brookelynpaisley · July 2010

Aw, very helpful, ladies. Thank you. I figured it had a lot to do with something like a textbook cycle, but I was curious.

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