Pregnancy tests are used to determine or verify a pregnancy in women. There are three types of pregnancy tests that are most popular today. These are the home pregnancy test, office urine pregnancy test and blood pregnancy test.

The home pregnancy test requires the collection of urine to test for hCG. hCG stands for human chorionic gonadotropin. This hormone is produced in a woman's body when the egg is fertilized and attaches to the body. In some pregnancies, the egg may attach in a place other than the uterus and while the home pregnancy test will read positive, the pregnancy will not be viable.

The office pregnancy test also requires the collection of urine. The office pregnancy test is often used to verify the results of the home pregnancy test. The two tests work in exactly the same way. The home pregnancy test results are considered valid for only a few hours after the test is taken and thus the need for a urine pregnancy test in the office.

Both the home and office urine pregnancy test will only be effective if the woman has missed her period. This is because the concentration of hCG in the urine is not high enough to show a positive result on a urine test until after the menstrual cycle is supposed to start.

While the home and office urine pregnancy test are the most common, the blood pregnancy test is the most sensitive. The blood pregnancy test can offer a bit more insight into the pregnancy for the obstetrician. Blood tests will not only verify the presence of a pregnancy, but the age of the fetus, as well. The amount of hCG in the blood will test higher, the further along the pregnancy is. If the mother is pregnant with multiples, the blood hCG levels will be higher than normal for the age of the fetus. This could result in the woman being called in for an ultrasound and the detection of multiple fetuses.

The urine pregnancy test can be performed at home. All that supplies needed for the test are included in the kit purchased at nearly any retail department store or drug store. The kit will include a stick with an absorbent tab. The absorbent tab will need to be wet with urine for the test to begin. These tests can be performed by holding the absorbent tab in the urine stream or dipping the tab into a cup holding fresh urine. The urine test, both at home and in the office, require three to five minutes to complete.

The blood pregnancy test can only be performed by a lab. Many obstetrician will draw the blood required for the test in the office and send the blood out to a lab for diagnosis. The blood pregnancy test may require up to 10 days for a final report. In very few cases, the lab can be located within the same building as the obstetrician or within the same office which can reduce the amount of time required for the blood test results to be returned to the doctor.

There are only a few instances when a false positive will appear on a pregnancy test. These instances are all related to the patient taking an infertility drug containing hCG. Infertility is defined as the inability to conceive. If the doctor is prescribing an infertility drug with hCG, the patient will not be able to perform an at home pregnancy test that is accurate.

There are no instances of drugs, either illegal or prescribed (other than infertility drugs), or alcohol causing a false positive pregnancy test result. A false negative pregnancy test result could mean the woman tested before the time when her menstrual cycle was due to begin. False negatives can also occur if the pregnancy is not viable and the body is not releasing hCG.