What Are the Chances of Home Pregnancy Tests Being Wrong?

Many women wonder if a home pregnancy test is always accurate. On television, women take pregnancy tests all the time and end up saying, "it was a false positive." In real life, pregnancy tests are accurate 99 percent of the time when used as directed one week after a missed period. That means a test will give a false answer only 1 percent of the time, and in most of these cases, it is due to improper use of the test.

False Negative Pregnancy Tests

A pregnancy test is generally designed to show a positive result when the woman's period is late, although some are sensitive enough to use sooner. A pregnancy test may show negative if the body is not yet producing enough pregnancy hormones to be detected by the test.

Defective Pregnancy Tests

It is possible to get a bad pregnancy test that will not show a pregnancy result even if the woman is pregnant. In most cases, the test line will not show up, signaling that the test is a dud.

False Positive Pregnancy Tests

Fertility medications that include pregnancy hormones can result in a positive pregnancy test when a woman is not pregnant. If the fertility drugs have enough pregnancy hormone in them, they may confuse the test.

False Positive After a Recent Pregnancy

A pregnancy test may show a positive result if you are testing soon after being pregnant, whether you gave birth or that pregnancy ended in miscarriage. It takes up to six weeks for the pregnancy hormones to dissipate, and a pregnancy test can read those remaining hormones as a new pregnancy.

Early Miscarriage and Pregnancy Tests

A woman may take a pregnancy test with a positive result only to have her menstrual cycle begin the next day. Doctors believe that over fifty percent of all pregnancies miscarry before the woman's menstrual cycle begins, so a woman who tests before she is "late" may show a positive result and still start her period on time.

References

• Mayo Clinic: Accuracy of Pregnancy Tests
• BabyCenter: Understanding Miscarriage

Resources

• PeeOnAStick: Pregnancy Test Research