How Accurate Are Home Pregnancy Tests?

Home pregnancy tests enable a woman to find out in the privacy of her own home if her family will be expanding. There is no longer a need to wait for a doctor's appointment to confirm a pregnancy. Pregnancy tests are simple to use, relatively inexpensive and widely available at a variety of retail locations. The type of test used, when the test is taken and ability to accurately read the results can all affect the accuracy of a home pregnancy test.

Facts

Home pregnancy tests analyze your urine for the presence of the hormone, HCG (human chorionic gonadotropin). This hormone is released shortly after the fertilized egg embeds in the uterine lining. The amount of hormone released increases rapidly in the following weeks.

While many tests boast that results can be accurate as soon as three to five days before your missed period, for the most accurate results, test after you have missed your period. As the HCG hormone increases in the body each day, the accuracy of the test increases.

Types

The most common type of home pregnancy test is the length of an average thermometer. The test works by holding the test in the stream of urine or by immersing the test in a clean container of urine for five to 10 seconds. Always read the instructions for the home pregnancy test because instructions can vary slightly by manufacturer.

A less common home pregnancy test requires mixing your urine with a powder or liquid solution. If the urine causes the solution to change in color, it indicates a positive result.

Features

Home pregnancy tests on the market today are relatively similar in the way the test is conducted. However, brands can have different sensitivity levels in recognizing the HCG hormone presence within the urine stream. The lower the sensitivity level, the more likely it is to get an accurate early result.

The reading in the results window of pregnancy tests can vary widely between manufacturers. Some tests indicate a positive or negative sign, some show lines, some change colors and some of the newer digital tests read pregnant or not pregnant. Even a faint positive indicates a positive test. Follow the directions on the box to accurately read your particular test.

Considerations

U.S. Department of Health and Human Services states, "Many home pregnancy tests (HPTs) claim to be 99 percent accurate on the first day of your missed period. But research suggests that most HPTs do not always spot pregnancy that early."

It is important to read the directions for your test. Some tests require only one minute to show results, while others may take as much as five minutes. If the test is read too soon or you wait too long, the results may be skewed.

First morning urine is the best to use for accurate results. The HCG hormone is more likely to be concentrated in this urine and the test has the best chance of detecting the hormone.

Misconceptions

A negative result does not necessarily indicate you are not pregnant. You may be testing too early to produce an accurate result. If your period has not started within a week of a negative result, you should retest.

According to the Mayo Clinic, a false positive can result if there is blood or protein in the urine. Certain over-the-counter and prescription drugs, such as diuretics, can also cause a false positive.

If you are uncertain about the result, you can test again or request a blood test administered at your doctor's office. The blood test accurately diagnoses pregnancy earlier than most urine tests.

References

• Mayo Clinic
• U.S. Dept. of Health & Human Services