Can home pregnancy test be false positive

Since the earliest recorded history, women have had a strong desire to know whether they are pregnant as early as possible. The body goes through countless changes in the first trimester, and one of the first indicators is a change in the hormones that leave the body through urine.

Table of Contents Show

Pregnancy test accuracy
When to see a doctor
What is a pregnancy test, and how does it work?
What types of pregnancy tests are available?
How accurate are pregnancy tests?
When to Take a Pregnancy Test
Where can I get a home pregnancy test?
What do the pregnancy test results mean?
What are the chances of a false
What would cause a false

Ancient Egyptians relied on a form of urine testing to determine pregnancy status way back in 1350 BCE. A woman urinated daily on wheat or barley seeds and if the plants grew, it meant she was pregnant. Modern-day validation suggests that test was about 70% accurate in detecting human chorionic gonadotropin (hCG), a hormone produced by a woman’s body soon after implantation of a fertilized egg inside the uterus.

Thankfully, urine-based pregnancy tests have evolved substantially. Women now have access to advanced tests that can detect a pregnancy as early as eight days after ovulation. But while many home pregnancy tests are marketed as simple and effective, getting accurate results comes down to how early in your ovulation cycle you take the test.

Ovulation generally occurs around day 15 of a 28-day cycle. In a normal pregnancy, an egg is fertilized in the fallopian tube and then travels into the uterus, where it implants in the uterine wall. After implantation, production of hCG starts from cells in the developing placenta (tissue that will feed the fetus). Trace levels of hCG can be detected as early as eight days after ovulation.

That means you could get positive results several days before you expect your period to start. However, the first part of your cycle is more variable than the second, making it tricky to determine the best time for an early test.

Pregnancy test accuracy

Each type of pregnancy test is designed to detect a set minimum level of hCG. This is why pregnancy test manufacturers advertise the way they do: “Know four days sooner,” or “Accurate up to six days before a missed period.” However, while home pregnancy tests are quite accurate – many boast a 99% detection rate based on laboratory testing results – marketing claims can be misleading.

For example, a 99% detection rate means a test can detect hCG 99% of the time on the day you miss your period. These statistics also assume that women are testing at the optimal time and following all instructions correctly.

Many home pregnancy tests available today are midstream urine dip tests, which are the traditional “pee-on-a-stick” tests and are fairly easy to use. There also are tests in which you pee into a cup and dip a test strip into the urine. The New York Times published a story ranking the best home pregnancy tests, citing a midstream test with an ergonomic grip as the easiest to use and most accurate.

Research has shown that average test results when women used the dip tests matched lab test results just 70% of the time, whereas 99% of women typically can get an accurate reading from a midstream test.

When to see a doctor

Most women who have a positive pregnancy test should wait a week or two before calling the Ob/Gyn office for a pregnancy blood test or ultrasound to confirm the pregnancy. We suggest waiting because the rate of early pregnancy loss is high, and it’s possible that you might have had a chemical pregnancy.

However, women with a history of ectopic pregnancy or current abdominal pain should call the doctor right away to be examined. Ectopic pregnancies implant outside of the uterus and produce hCG, resulting in positive pregnancy tests. However, these pregnancies can cause abdominal bleeding and prompt medical care is necessary. Women who have congenital heart defects or other chronic physical or mental health conditions should also see a doctor right away because treatment plans or medications might need to be altered to protect the woman and the fetus.

Advances in home pregnancy tests give women greater insight into what’s going on in their bodies sooner than ever before. No matter what your childbearing plans might be, it’s essential to get quick, accurate results at home to plan your next steps accordingly.

A pregnancy test can let you know if you are pregnant. Here are answers to some common questions about them.

What is a pregnancy test, and how does it work?

Pregnancy tests check your pee or blood for a hormone called human chorionic gonadotropin (hCG). Your body makes this hormone after a fertilized egg attaches to the wall of your uterus.

This usually happens about 6 days after fertilization. Levels of hCG rise quickly, doubling every 2 to 3 days.

What types of pregnancy tests are available?

Two main types of pregnancy tests are blood tests and urine tests.

Blood tests

You get these at your doctor's office, but they’re not used as often as urine tests. These tests can detect pregnancy earlier than a home pregnancy test, about 6 to 8 days after ovulation. It takes longer to get the results than with a home pregnancy test.

The two types of blood pregnancy tests are:

A qualitative hCG test simply checks for hCG. It gives a "yes" or "no" answer to the question, "Are you pregnant?" Doctors often order these tests to confirm pregnancy as early as 10 days after conception. Some can detect hCG much earlier.

A quantitative hCG test (beta hCG) measures the exact amount of hCG in your blood. It can find even very low levels of hCG. These tests may help track problems during pregnancy. Your doctor may use them along with other tests to rule out an ectopic pregnancy, when the fertilized egg implants outside your uterus, or after a miscarriage, when hCG levels fall quickly.

Urine tests

You can take these at home or in a doctor's office.

Along with being private and convenient, home pregnancy tests are quick and easy to use. They’re also very accurate if you follow the directions. These pregnancy tests all work in a similar way. You test your pee in one of these ways:

Hold the test stick in your urine stream
Collect pee in a cup and dip the test stick into it
Collect pee in a cup and use a dropper to put it into another container

You’ll need to wait a few minutes before seeing the results.

After you take this test, you can confirm your results by seeing your doctor, who can do even more sensitive pregnancy tests.

How accurate are pregnancy tests?

Urine home pregnancy tests are about 99% accurate. Blood tests are even more accurate.

A home test’s accuracy depends on:

How closely you follow the instructions
When you ovulate and how soon the egg implants
How soon after pregnancy you take the test
The sensitivity of the pregnancy test

When to Take a Pregnancy Test

Some pregnancy tests can spot hCG before you miss a period. But the results will be more accurate if you wait until the first day of a missed period.

Results may also be more accurate if you do the test first thing in the morning, when your urine is more concentrated.

Where can I get a home pregnancy test?

You can buy a home pregnancy test in a drugstore without a prescription. The cost depends on the brand. But most tests aren’t very expensive.

What do the pregnancy test results mean?

Results may show up as a line, a color, or a symbol such as a "+" or "-" sign. Digital tests show the words "pregnant" or "not pregnant." It's important to know what a positive or negative result means.

If you get a positive result, you’re pregnant. This is true no matter how faint the line, color, or sign is. If you get a positive result, you may want to call your doctor to talk about what comes next.

In very rare cases, you can have a false-positive result. This means you're not pregnant but the test says you are. You could have a false-positive result if you have blood or protein in your pee. Certain drugs, such as tranquilizers, anticonvulsants, hypnotics, and fertility drugs, could cause false-positive results.

If you get a negative result, you’re probably not pregnant. But you may be pregnant if:

The test is past its expiration date.
You took the test the wrong way.
You tested too soon.
Your pee is too diluted because you drank a lot of fluids right before the test.
You’re taking certain medications, such as diuretics or antihistamines.

If you get a negative result, try retesting within about a week to double-check. Some home pregnancy tests suggest doing this no matter what your first results are.

If you take the test twice and get different results, call your doctor. A blood test is a good idea to confirm results.

If you have any other questions about the pregnancy test or the results, call your doctor or the telephone number listed with the test.

Show Sources

SOURCES:

American Pregnancy Association: "Understanding Pregnancy Tests: Urine & Blood, "Taking a Pregnancy Test," "Pregnancy FAQ: Early Pregnancy."

What are the chances of a false

A false-positive test result only happens less than 1% of the time, but when it does, it can make the following days or weeks confusing before you realize you're not actually pregnant. So what actually causes a false-positive test and how do you decrease the chances of it happening to you?

What would cause a false

A test will only show a false positive if you have hCG in your system for another reason such as you were recently pregnant, are taking fertility medications containing hCG, or if you have a medical condition, like some rare ovarian cysts.