Pregnancy Test Results

Pregnancy tests are a reliable tool for detecting early pregnancies for many women. The pregnancy test kits available at drug stores are preferred by women instead of laboratory tests. More often than not, these kits produce reliable results with an accuracy of 99%. Nonetheless, these tests are subject to a lot of variation, either due to incorrect reading of the tests or due to interference of certain external factors. Hence, it is a must that you know how to read pregnancy test results and what are the factors that influence them.

How Do Pregnancy Tests Work
Pregnancy tests work by detecting the presence of a hormone named Human Chorionic Gonadotropin (HCG). The hormone is secreted by placenta, which provides nourishment to the developing embryo. When the fertilization takes place, the fertilized egg or zygote travels to the uterus from the fallopian tube and attaches itself to the lining of uterus leading to conception. Thus, it may take several days for the egg to fertilize and the zygote to finally reach the uterus. As a result, you should consider the day of conception as a reference point for taking the test and not the day of intercourse. It is recommended that you wait until the first day of your missed period to take the test. Pregnancy tests before missed period may not produce reliable results.

The test kits are capable of detecting the small amount of HCG in the urine of a pregnant woman. Accordingly, a test result appears on the strip. The expression of the result varies according to the manufacturers of test kits. In some kits, positive pregnancy test is characterized by two faint pink lines while for some a plus sign is a symbol for positive pregnancy. Morning urine sample is considered best for these tests as it contains the maximum amount of HCG.

Factors Affecting Pregnancy Test Results
While opting homemade tests or EPT test kit, it is necessary that you follow the instructions on the kit, word for word. Erroneous testing can produce misleading results. The urine sample taken for the purpose of testing should be inside the bladder for at least 4 hours. Diluted urine samples do not have enough amount of HCG to be detected by the test. Similarly, the test should be conducted for the prescribed time only. Prolonging the test can result in false positive pregnancy while ending it early may result in false negative pregnancy. False positive and false negative pregnancies are discussed later in this article. Besides, certain medications also interfere with the test results. The sensitivity of the pregnancy kit is yet another factor to be considered while evaluating test results. EPT results are more accurate for kits with a sensitivity of 20 mIU/ml (milli International Units per milliliters) than those with a sensitivity 50 to 100 mIU/ml.

False Positive Pregnancy
False positive pregnancy results are generated when the test shows you are pregnant, even though you are not. Chemical pregnancy is often a reason for false pregnancy results. Chemical pregnancy is said to have occurred due to early miscarriage. The traces of HCG are detected even though there is no growing embryo. Besides, some medications also produce traces of HCG which can be picked by the test. However, it is a very rare phenomenon, as the HCG produced by medications is in negligible amounts. Prolonging test duration is a main cause of false positive test results. Women are often so desperate to get pregnant that they ignore the prescribed time limit.

False Negative Pregnancy
False negative pregnancy test result is generated when the test results show negative even though you are pregnant. This is mainly because either you conducted the test too early or there was not enough HCG to be detected. The HCG levels at same gestational stage are different for every women. The test result interpretation is done on the basis of average HCG level at a particular stage.

If there is any ambiguity regarding the test result, then you may repeat it after two days, because during very first days of pregnancy, the levels of HCG double every two days.