When to Take a Home Pregnancy Test

Home pregnancy tests are designed to detect the presence of human chorionic gonadotropin (hCG), the hormone manufactured by the blastocyst (the name for the hollow clump of cells resulting from the meeting of sperm and egg) following implantation. Enough hCG is present in the urine to allow a pregnancy to be confirmed as soon as nine to 12 days after conception, although it takes some pregnant women a little longer to test positive.

It may not be in your best interest to jump the gun on testing, however. Studies have concluded that the best time to do a home pregnancy test is a week after your period is due. While most women would argue that you would have to have the patience of a saint to wait that long, there's a case to be made for waiting: if you get a false negative because you've tested too early—in other words, the test says you're not pregnant when, in fact, you are—you might not be quite as careful about avoiding alcohol and other potentially harmful substances as you would if you believed that you were pregnant. The researchers involved in this study concluded that approximately 10 percent of pregnancies are missed when home pregnancy tests are performed on the day that a woman's period is due.

If you do decide to test early and you get a negative result, you'll want to take that negative test result as a "probably not pregnant" rather than a "definitely not pregnant" and either do another home pregnancy test in another couple of days if your period still hasn't started or get in touch with your doctor to see if she can order a more sensitive pregnancy blood test.

And until you know otherwise, you should continue to play the part of the mama-to-be by avoiding anything that could be potentially harmful to a developing baby.