Home pregnancy tests are used to ascertain whether a woman is pregnant or not without a doctor's help. When used exactly as instructed these tests produce similar results to the tests performed in clinics.

These tests determine whether pregnancy has taken place by detecting the presence of a hormone called human chorionic gonadotropin or hCG in a sample of urine.

A woman becomes pregnant when the egg (ova) is fertilized by a sperm cell in the fallopian tube. Within nine days the fertilized egg moves down the fallopian tube into the uterus and attaches to the wall of the uterus. When the fertilized egg attaches, the placenta starts to develop and begins to release hCG hormone into the woman's blood. Some of this hCG hormone also gets passed in her urine. In the first early weeks of pregnancy, the amount of hCG in the urine rises rapidly, doubling almost every 2 to 3 days.

There are three basic types of pregnancy tests. The most common types of home tests make use of a test strip that has to be dipped into a sample of urine. If the area on the end of the strip changes color, it confirms pregnancy. A second type of pregnancy test makes use of a urine collection cup attached with a testing device. Another less common test involves mixing urine sample with chemicals in test tubes to produce a chemical reaction. All of these tests confirm a positive or negative result via change in color.

There is no risk involved in doing these tests other than maybe getting a wrong report. The accuracy of these tests depends on a woman's menstrual cycle and the exact day of implantation of the fertilized egg. Home pregnancy tests can be used on the first day of a missed menstrual period. However, for accurate results wait a few days longer. If you perform the test as soon as you have missed a period and the results indicate you are not pregnant, repeat the test in one week if your menstrual period has not yet started.