How reliable are (home) pregnancy tests?

[red_hoodie]

I've heard that if you take a pregnancy test and it's negative you might still be pregnant (you might have tested too early, hormone levels might be abnormally low, etc.) but if you get a positive pregnancy test you are pregnant (unless you've had fertility treatments).

Is this true?

I've heard a lot of women tell me that they tested negative on a pregnancy test when their period was due and kept getting negatives until about two weeks after their period was due.

[Heather]

Exactly as reliable as they say on their boxes (they would be breaking laws otherwise), which is around 99%.

And indeed, false negatives are way, way more common than false positives, which are highly unusual. I don't know how many women "a lot" is, but by all means, pregnancy tests generally can only usually work after a period is late or missed, and that generally will be at least around a week after it was expected, so what you're describing isn't that far outside that window, and is as we'd expect. In other words, it sounds like the women you have talked to about this maybe didn't realize that in general medical parlance, a late period is one that's five or more days later than the very latest it was expected by, and may have taken tests too soon.