Home Pregnancy Tests - The Facts

Home Pregnancy Tests (HPTs) test for one thing; HCG. HCG stands for Human Chorionic Gonadotropin and is more simply put the pregnancy hormone. HPTs work by placing urine on the test strip. If HCG is detected it will activate the test strip giving you a positive result. There will also be what is called a control line which shows up to let you know the test is working properly. Two lines equals pregnant. Sounds simple, huh? But wait, what about evaporation lines, chemical pregnancies and late implanters?

Evaporation lines are caused by the drying of the test antibody strip. These are considered negative results. Evaporation lines can appear at any time. Usually they will appear after the time limit for the test. They can appear as gray, shadowy lines. Some will be very thin while others can be the width of the control line. They can also appear in color after the time limit of the test.

Chemical pregnancies are basically early miscarriages. They account for the majority of false positives. Conception occurs at ovulation however it takes 7-12 days for the egg to travel down the fallopian tube to implant in the uterus. Once implantation occurs, that is when HCG is secreted. So if you test before your missed period and get a positive but get your period a few days later its possible you have experienced an early miscarriage.

As noted before, implantation takes place around 7-12 days after ovulation. There are new early result HPTs that say you can get a positive 4-5 days before you miss your period. If you happen to be the person who implants at 12 days then you will get negative results until the day of your period. This would be considered a false negative.

Another problem with testing early is faint lines. There is always something "there". The test antibody strip is visible and if you have to hold the test to the light squint one eye and close the other while angling the HPT, then you're probably going to need to consider that a negative, wait two days and try again.

There is a newer type of test that is available now; the digital. It will pop up with the "Pregnant" or "Not Pregnant". The digital HPTs tend to be more expensive. However you should weight the importance of the stress of "is it a line?" over the money spent. It just might be worth the investment.