hCG Tests to Detect Pregnancy

A missed period has always been considered as the earliest sign of pregnancy. In fact, this may not be a reliable symptom to confirm pregnancy. Hence, most women resort to home pregnancy tests, before going to a gynecologist.

But compared to the yesteryear, when women used to collect urine samples and approach doctors, who were authorized to use pregnancy test kits; the modern-day home pregnancy tests are far more advanced and convenient.

The history of pregnancy tests can be traced back to the period of the ancient Greeks and Romans. The ancient Egyptian women used to mix grains of wheat or barley with their urine to detect pregnancy. Pregnancy was confirmed on germination of the grains.

Hippocrates, the renowned ancient Greek physician, advised women to consume a solution of honey and water at bedtime; and women who developed cramps were determined to be pregnant.

The fussy pregnancy kits of the 1970s were meant to be used under the supervision of doctors or in laboratories. The modern-day home pregnancy test kits were developed during the end of the twentieth century.

Early pregnancy tests include two methods - one using urine samples and the other using blood samples. The theory behind both tests are the same, but the methods are different.

Both tests are designed to check the presence of the hormone human chorionic gonadotropin (hCG), which is secreted by the developing placenta, soon after the fertilized egg gets attached to the lining of the uterus.

This implantation can happen anytime between 6 to 12 days of ovulation. While the blood test is usually done at a doctor's office or in a laboratory; urine samples can be tested at home, using pregnancy test kits.

Using a home pregnancy test kit is an easy and quick way to detect pregnancy during the early stages. The method may vary with the type of test. Place a few drops of urine into the well marked on the testing stick, or urinate directly on the stick; and wait for the stipulated time to see the results. The result is displayed in various symbols or colors.

The latest digital pregnancy test kits display the results in writing, like 'pregnant' or 'not pregnant'. Make sure to read the instructions carefully and follow them for accurate results. It is always better to use morning urine, while using pregnancy test kits.

Test Sensitivity: The level of hCG increases with the progressing stages of pregnancy, and the early stages are characterized with very low hCG levels. Most of the home pregnancy tests available today have a high level of sensitivity. The sensitivity of a pregnancy test kit means the level of hCG it can detect.

This hormone (hCG) is measured in thousandths of International Units or mIU. Those tests which can detect very low levels of hCG (like 20mIU) are considered more sensitive then those which can detect higher levels (50 to 100 mIU) of hCG. If the test is indicated as capable of detecting low levels of hCG, then it can detect pregnancy at a very early stage.

The most sensitive home pregnancy tests can detect pregnancies within eight days of ovulation. Some of the less sensitive pregnancy test kits may not be able to detect early pregnancies and may show negative results. In that case, you may use a high sensitivity home pregnancy kit or wait for a few more days, before testing again.

While home tests with urine samples can detect hCG within a range of 20 mIU to 100 mIU, pregnancy tests done on blood samples can detect hCG, at the lowest level of 1 mIU. So the blood test is more sensitive, as it can detect pregnancies earlier than the most sensitive home test.

Apart from these two methods, early pregnancy tests include another method called rosette inhibition assay for early pregnancy factor (EPF), which can detect pregnancy within 48 hours of fertilization. But this method is very expensive and time-consuming (and it cannot be done at home).

Ultrasound can also be used to detect pregnancy, but this test can detect the gestational sac only after 18 to 20 days from the date of fertilization.

According to researchers, home pregnancy tests are 97% accurate, if done correctly. These tests are inexpensive, easy to use, and give faster results, compared to other methods. However, you have to approach a gynecologist and confirm the result, even if your home pregnancy test result is positive.

Disclaimer: This is for informational purposes only, and should not be used as a replacement for expert medical advice. Visiting your physician is the safest way to diagnose and treat any health condition.