Q&A: Are home pregnancy tests ever wrong?

This may be an exciting (and scary) thought: you could be pregnant! Before you go out and buy a home pregnancy test (HPT), let's quickly talk about how they work.

HPTs check for the presence of hCG (human chorionic gonadotropin). This hormone is produced after fertilization occurs and is responsible for many of the early symptoms of pregnancy.

An HPT can be used as soon as the first day after your missed period, which is approximately two weeks after fertilization. Later, you may call your OB and get a blood test to confirm your pregnancy. This is done in your doctor's office about one week after conception.

If you follow all the directions provided by the HPT manufacturer and you get a positive result, chances are pretty good that you are indeed pregnant. However, an HPT may give you a negative results if you test too early or if you don't follow the package instructions.

If you really believe you are pregnant and the results are negative, wait until the next morning and try testing again. (Most kits have two tests to deal with mistakes or to satisfy your need to re-test.) Here's a helpful hint: hCG tends to be highest and more concentrated in your urine in the morning, so this is the best time to test for the most accurate results.

When you do see a positive result in a HPT, it is time to call your doctor to schedule that blood test to confirm your results.