Could you be pregnant? Before you head to the drugstore to buy a test, learn how they work, how to take one, and the surprising truth about the best time to do it.

How do they work?
Home pregnancy tests work by detecting hCG, or human chorionic gonadotropin, the telltale pregnancy hormone produced by the placenta. All tests essentially work the same way, so there's no need to dish out extra cash for a particular brand.

What the best time to take one?
TV commercials may have you believing that you can test as soon as 5 days before your expected period. But what they don't tell you is that many women don't produce enough hCG for the test to detect a pregnancy that early. "Two weeks after conception, there will be enough HCG to form a positive result for most women," says Robert Resnick, M.D., Professor Emeritus of Reproductive Medicine at the University of California at San Diego School of Medicine. So unless you want to shell out for multiple tests, and possibly drive yourself crazy wondering if you got a false negative, it's best to wait at least until the day you would have gotten your period.

How do you take one?
First of all, make sure your test hasn't expired. Your first urine of the day is the most concentrated, so that's the best time to take a test (although you'll probably get the same result any time of day). Then read the instructions very carefully before peeing on the stick and waiting for the results. Some will register one or two lines, some a plus/negative sign, while others will give you a digital -- and decisive -- "yes" or "no."

Is it better to do one at the doctor's office?
In general, the test they'll do at your OB/GYN is exactly the same. However, they can also do a more sensitive blood test if you're getting a negative result but still think you may be pregnant.

Can I get a false positive?
"It's extraordinarily rare to get a false positive," says Dr. Resnick. However, if your test is negative, and you still don't get your period, test again in a day or two. It may just be that your hCG levels weren't high even for detection. What about a light positive, where you think you see a line but aren't sure? You're most likely pregnant. Wait a day and test again, or ask your OB/GYN for a blood test.

If I'm pregnant, what should I do next?
Congratulations, mama! Once you've shared the happy news with your partner, make your first prenatal appointment with your OB/GYN.

Stumble Upon Facebook Del.icio.us Google Yahoo Digg it