Do you think you might be expecting a baby? For most people, a home pregnancy test is the easiest way to find out if you’re pregnant. These tests are over 99% accurate if performed correctly. They’re inexpensive and can be found at most pharmacies.
If you want to know how to get the most accurate results possible from your pregnancy test, read our guide that tells you everything you need to know, including what to do and what not to do before taking a pregnancy test.
How do home pregnancy tests work?
Home pregnancy tests work by detecting a hormone called human chorionic gonadotropin (hCG). This hormone is produced by the placenta during pregnancy and is present in urine after the fertilized egg implants in the lining of the uterus (about 6-12 days after conception). As your pregnancy progresses, your body produces increasing amounts of hCG.
The presence of hCG will give you a positive pregnancy test, while the absence of hCG will give you a negative pregnancy test. Taking a pregnancy test too early can also give you a false negative result, which occurs when hCG levels have not yet risen high enough for a pregnancy test to detect.
Types of pregnancy tests and how to use them
There are two types of home pregnancy tests: digital and non-digital. Here’s how to use each one. (You can also have your doctor do a blood test to confirm pregnancy.)
Non-digital pregnancy tests
These tests come in a variety of formats, including standard test strips and pregnancy tests. Some pregnancy tests can be applied directly to the test strip, while others require you to dip the strip into a cup of urine. (Be sure to read your pregnancy test packaging for brand-specific instructions.)
Pregnancy tests contain antibodies coated with a chemical that bind to hCG if it is present, giving a positive result. Depending on the particular test strip, a positive result is usually indicated by one of the following signs:
- Plus sign
- Faint lines (usually pink or blue)
- Color change
If the molecule does not bind to any hCG, you will get a negative result. When reading the test result, it is very important to read it within the time stated on the test result. Waiting too long or reading too soon can result in an inaccurate answer or a disappearance of the line.
Digital Pregnancy Test
Digital tests look like non-digital pregnancy tests but have a screen. They also rely on what they call “rapid tests” that can give results in just three minutes. This method combines a biochemical process with antibodies to detect hCG.
With a digital test, there’s no guessing, just an answer of “pregnant” or “not pregnant.”
Digital tests are available at grocery stores and pharmacies, but keep in mind that they tend to be a bit more expensive, plus they tend to require more hCG to get a clear result and are more prone to error (often resulting in false negatives, especially if the test is taken too early).
What is a false negative pregnancy test?
In some cases, you may get a false negative result if your hCG levels are too low to be detected early. This is especially common if you take an “early detection” test that promises results three, four, or five days before your period is late.
When to take a pregnancy test
After conception, it takes some time for hCG to build up in your body. The earliest you can get a positive pregnancy test is six days after ovulation, but this is very unlikely and everything needs to go smoothly for this to happen. Typically, you should wait at least seven to ten days to get an accurate pregnancy test result (although results are most accurate after the first day of your missed period).
Keep in mind that everyone’s body is different, so it may take multiple steps to achieve good results.
- First, you need to have sex close to ovulation (when an egg is released from the ovaries and travels through the fallopian tubes). Because sperm can live in a woman’s reproductive system for up to five days, sex should occur around the time of ovulation or five days before ovulation.
- The fertilized egg must then travel through the fallopian tube and implant in the uterus.
- Ultimately, hCG levels must be detectable in your body, and only then will a home pregnancy test kit show a positive result.
When can hCG levels be detected?
Sometimes hCG reaches detectable levels before your period is late, but sometimes it doesn’t, says Danielle Roshan, M.D., an obstetrician-gynecologist at the Roche Institute for Maternal-Fetal Medicine in New York City. Because hCG levels double every 48 to 72 hours, taking a pregnancy test after your period is late is more likely to be accurate, says Dr. Roshan.
For those with irregular menstrual cycles, the general rule is to wait three weeks after sex before using a home pregnancy test kit.
Most manufacturers recommend taking a home pregnancy test twice, as taking the test too early can change the results, which eliminates the possibility of a false negative result.
Early Pregnancy Symptoms
If you have had unprotected sex and notice any of the following early symptoms of pregnancy, you should get tested using a home pregnancy test:
- Chest pain
- tired
- nausea
- Dysfunction
- Frequent urination
- Bleeding or cramping during transplant
- Mood swings
- constipate
Are home pregnancy tests accurate?
Home pregnancy tests are around 99% accurate if used correctly and taken after your missed period. It’s possible to get a false negative result (when the test says you’re not pregnant when in fact you are). The most common reason is taking the test too early, but it can also happen if you don’t follow the instructions.
If your period is late and doesn’t come after a few days, try again or talk to your healthcare provider, says obstetrician-gynecologist Marla Francis, M.D. Irregular periods can be caused by illness, certain medications, being too thin or overweight, excessive exercise, stress, or hormonal birth control pills.
Even more rarely, false positive results can occur (when the test says you are pregnant when you are not). False positive results occur primarily in people taking fertility drugs, but can also be caused by an outdated pregnancy test, a recent miscarriage or abortion, a miscarriage shortly after implantation (chemical pregnancy), or an ovarian tumor.
Here are some tips to help make your pregnancy test more accurate:
- Check the expiration date on your pregnancy test before using it.
- Test first thing in the morning, as levels of hCG in urine are usually highest that day.
- Do not drink large amounts of fluids before taking a pregnancy test, as this may dilute the concentration of hCG in your urine and give you a false negative result.
- Certain medications, such as prescription fertility medications, can interfere with pregnancy tests. For better results, your healthcare provider may recommend an in-office test.
- Improper use or exposure to sunlight can also lead to inaccurate results. Always use pregnancy tests as directed.
- Always read test results within the recommended time frame.
My pregnancy test is positive, what should I do?
If the test is positive and you’ve followed all the right steps, you can rest assured that you are indeed pregnant. The next step is to call your obstetric care provider, who will likely schedule an appointment for a prenatal checkup.
For many people, a pregnancy blood test is not necessary to confirm a pregnancy, but depending on your health history and current health conditions, your doctor may want to schedule an ultrasound scan early in your pregnancy.
You should also start taking prepregnancy vitamins while you are waiting for your appointment (ideally while you are trying to conceive). Pregnant women should stop smoking and drinking alcohol and limit their caffeine intake.
