Home Pregnancy Test Accuracy

Most women simply cannot wait to get pregnant when they decide to start a family. In their pursuit of detecting pregnancy as early as possible, they rely on pregnancy kits that are widely available. However, the pregnancy test accuracy of these kits is highly questionable. Most manufacturer's claim their accuracy to be 99%, however, this is greatly dependent upon certain variable factors. Before we delve deeper into the accuracy of home pregnancy test, let us find how pregnancy is detected in the first place.

How Pregnancy is Detected

Most pregnancy tests rely upon the presence of Human Chorionic Gonadotropin (HCG) hormone to detect the pregnancy. Pregnancy can be detected either by testing urine or by testing blood, since the hormone shows its presence in both of these fluids. This hormone is secreted by the placenta after fertilization takes place. When the ovum is fertilized by the sperm, the fertilized egg or zygote attaches itself to the lining of uterus. This is when conception is said to have occurred. The placenta is responsible for providing nutrition to the growing zygote and secretes a hormone HCG. Normally, HCG is not present in the body, or even if it is present it cannot be detected during the tests. However, in pregnancy HCG is secreted in large amounts so that it can be detected in blood or urine. In fact, during the first few weeks of pregnancy, the amount of HCG gets doubled every two days. Hence, you can always retake your pregnancy test if you are not sure about the results.

Factors Affecting the Accuracy of Pregnancy Tests

As mentioned above, accuracy of a home pregnancy test is affected by several factors. The sensitivity of the pregnancy kit is one of the most important factor to be considered. Pregnancy tests with a sensitivity of 20 mIU/ml have more sensitivity than tests with 50 to 100 mIU/ml. As a result, they are more likely to produce accurate results. Reading the manufacturer's instructions on the kit also goes a long way in determining the accuracy of pregnancy test. If you do not follow the instructions carefully, you are most likely to get incorrect results. Moreover, you should also know how to read a pregnancy test correctly. Usually, it is recommended that you use first morning urine as sample as it has the maximum concentration of HCG. If you drink lots of water or collect a frequent urination sample then the HCG gets diluted and cannot be detected in the test. As a result, you may get inaccurate results. Hence, always make it a point to use urine that has been held in bladder for more than 4 hours.

Blood pregnancy test accuracy is likely to affect, if you are taking certain fertility drugs or other medications. Some non pregnant women may have tissues secreting HCG, which may result in positive pregnancy result, even though she is not pregnant. However, this is unlikely to happen as the HCG secreted in non pregnant women is in traces and hence cannot be detected. The time when you decide to take the test also has implications upon the test results. Pregnancy test accuracy before missed period is highly unreliable with the help of available tests. Only a few tests can accurately detect pregnancy on the day of the missed period while pregnancy test accuracy after missed period is reliable for most kits.

Pregnancy Test Accuracy Comparison

Pregnancy test results vary according to the type of test performed. Urine pregnancy tests at laboratory may produce different results than homemade pregnancy tests. Laboratory tests are more reliable than home pregnancy tests. However, this is only true if HCG levels are just around the threshold. If higher HCG is present, even the home tests are unlikely to go wrong. Besides, the HCG secreted by every woman at same gestational stage is different and the threshold is defined by the average levels of HCG at that stage, which may at times lead to misinterpretation of results. False positive or false negative pregnancy test can also result in unreliable accuracy of pregnancy tests taken at home.

If you are doubtful about the urine pregnancy test accuracy, you may either take blood test or repeat the urine test after a couple of days. Ambiguous results are generated only at very early stage of pregnancy. After that, most of the tests should be able to give you accurate results.