How Conclusive is a Positive Pregnancy Test?

Maybe you just have a “feeling” or perhaps you’ve had an upset stomach the last couple of mornings. You’re thinking you might be pregnant. Before you reach for that at-home pregnancy test, STOP. How conclusive is a positive pregnancy test? Does it depend on when it’s taken?

Actually, yes. If you take a pregnancy test too early, you risk getting an incorrect reading, causing you to think you’re pregnant when you really aren’t or thinking you aren’t pregnant and you really are.

Be Patient

The first thing you need to do is calculate the day your period is expected. To do this, take the first day of your last period and count forward 28 days. That will be the estimated start of your next menstrual cycle.

Hold on, though! Even though many companies claim their tests can be taken the day your period is due, or even before that, you will benefit from waiting until the second day.

Why wait? Mayo Clinic says, “Shortly after a fertilized egg attaches to your uterine lining, the placenta forms and produces the hormone human chorionic gonadotropin (HCG). This hormone enters your bloodstream and urine… The earlier you take the home pregnancy test, the harder it might be for the test to detect HCG… If your periods are irregular, you might have a hard time figuring out when your period is due.”

How Do Pregnancy Tests Work?

Home pregnancy tests use urine to detect HCG. Tests vary for use—some say to place a stick into your urine stream, while others use a collection cup to then dip a stick into or use a dropper to place urine on the unit where designated.

After waiting the prescribed amount of time, usually just a couple of minutes, the results will show in a window on that stick. This can display in a few different ways—as a plus or minus sign, with the words pregnant or not pregnant, or one or two lines. The Directions for Use included with each test will explain what exactly you should look for.

Ways to Get a False Positive Result

There are several ways to get a false positive result. The best way to avoid this is by reading the directions thoroughly before taking the test. Instructions can vary from test to test, so don’t assume you know how the one you are using right now works.

Evaporation lines: Make sure to read the result in the prescribed time period. If you wait too long, and you have a non-digital test, you may see a line that you think means you are pregnant. In reality, it could be the evaporation line from the urine.

Previous miscarriage or abortion: When pregnant, the hormone HCG is secreted and after a miscarriage or abortion the levels will drop slowly, ending between nine and 35 days after this event. Taking a test within this time frame could result in a false positive.

Molar pregnancy: This is a condition that causes a uterine tumor to grow and is caused by a genetic abnormality at conception resulting in an abnormal pregnancy where only the male chromosomes are present. When this occurs, a dilation and curettage is required to remove the abnormal tissue.

Medications: There are certain medications that can lead to a false positive pregnancy test. Generally, these medications contain HCG and are used to treat infertility.

Medical conditions: There are some medical conditions that can cause a false positive because they cause HCG to rise when not pregnant. Some of those include disorders affecting the pituitary gland, certain cancers, phantom HCG, ovarian cysts, and urinary disease or urinary tract infections.


If used following the instructions carefully, and patiently waiting an extra day after a missed period, home pregnancy tests can be 99 percent accurate, according to the United States’ Office on Women’s Health.

Positive Pregnancy Tests are NOT Conclusive

If you get a positive reading on a home pregnancy test, call to schedule a visit at Willow Womens Center for a pregnancy test to confirm your results. A positive pregnancy test is not conclusive. The best way to determine how far along you are and the viability of your pregnancy is with an ultrasound. We offer you a no-cost pregnancy test and ultrasound and will help you determine the need for an STI screening.

Make an appointment to come to Willow Womens Center. We care about you holistically: physically, emotionally, spiritually and want to support you in all of those areas.

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