We rely on pregnancy tests for a lot when you think about it. If you spent more than one or two months trying to conceive, or have had fertility difficulties, that positive pregnancy test can be a truly historic event. Likewise, a negative pregnancy test can generate a ton of negative emotional energy.

You might not realize it after taking (and tossing) handfuls of failed pregnancy tests, but a pregnancy test doesn’t always keep its result over time. You might take the pregnancy test and, in as little as 24 hours later, the positive result line (and probably the control line) can be gone.

What does a fading pregnancy test mean?

A positive pregnancy means precisely one thing: there is enough human chorionic gonadotropin in your urine to produce a chemical reaction with the pregnancy test. It’s no more or less than that.

There are several reasons that a pregnancy test might fade, including:

• Time. Depending on the test brand and type, the chemicals in the test strip that caused a reaction with your urine may evaporate. That doesn’t mean you’re not still pregnant. It just means there isn’t a physical demonstration of that chemical reaction.
• Defective tests. Quality control is essential when you’re talking about pregnancy test strips. There are very few brands that have issues with faulty tests. There may be batch issues, but for the most part, most tests you can buy these days will work as advertised.

 What if a second test says I’m not pregnant?

Here again, it’s all about chemistry. You’ve got a couple of options here, too:

• Defective tests. Most of the time, a faulty test strip is more likely to show a false negative than a false positive. It could be that the second pregnancy test was defective.
• Early miscarriage. Sadly about 30% of pregnancies end in miscarriage, but most of those occur before or around the time you’d miss your period. If you tested early with a highly-sensitive strip and then tested negative later, you may have experienced an early miscarriage.