Think you might be expecting a baby? For most people, taking an at-home pregnancy test is the easiest way to find out if you're pregnant. These tests are more than 99% accurate if taken correctly. They're also inexpensive and can be found at most drug stores.
If you're wondering how to take a pregnancy test to get the most accurate results possible, read our guide for 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 is produced by the placenta during pregnancy and is found in your urine after a fertilized egg implants in the uterine lining (about six to 12 days after conception). Your body makes increasing amounts of hCG as the pregnancy progresses.
The presence of hCG leads to a positive pregnancy test result, while lack of hCG causes a negative result. You can also get a false negative by taking the test too soon; this happens if hCG levels didn't rise enough yet to be detected by the test.
Types of Pregnancy Tests and How To Use Them
There are two main types of at-home pregnancy tests: digital and non-digital. Here's how to use each of them. (Also note you can get a blood test from your health care provider to confirm a pregnancy.)
Non-digital pregnancy tests
These tests come in many different forms, including standard sticks and test strips. You can pee directly on some pregnancy sticks, while test strips should be dipped in a cup of urine. (Always read the packaging of your pregnancy test for your brand's specific instructions.)
Pregnancy tests contain antibodies coated with a chemical that bonds to hCG if it's present, delivering a positive result. Depending on your specific test, positive results are usually indicated by one of the following:
- A plus sign
- A faint line (usually pink or blue)
- A color change
If the molecules do not bond with any hCG, you get a negative result. It's also very important to read the results within the time frame listed on the test, as waiting too long or reading it too quickly could give you an inaccurate answer or an evaporation line.
Digital pregnancy tests
Digital tests look similar to non-digital pregnancy tests, but they have a screen. They also rely on a method called "rapid assay delivery," which might give results in only three minutes. This method combines a biochemical process with antibodies that detect hCG.
With digital tests, there's no guesswork—it will simply say "pregnant" or "not pregnant."
While digital tests are available at grocery stores and drug stores, they tend to be a little bit more expensive, so keep that in mind. Also, digital tests tend to require higher amounts of hCG to deliver a clear result, which means their tendency for errors is higher (typically false negatives, especially if you take the test too early).
What Are False Negative Pregnancy Tests?
In some cases, if your hCG levels are too low to catch early on, you may get a false negative result. This is especially common if you take "early detection" tests that promise results three, four, or even five days before a missed period.
When To Take a Pregnancy Test
After conception, it takes a while for hCG to generate in your body. The earliest possible time to get a positive pregnancy test is six days post-ovulation, but that's incredibly rare and requires everything to go seamlessly in order to happen. Usually you must wait at least seven to 10 days for an accurate pregnancy test (but results are most accurate after the first day of your missed period).
Keep in mind that everyone's body is different, and a positive result requires several steps.
- First, you must have sex near ovulation (when an ovary releases an egg and it travels down the fallopian tube). Sperm can live for up to five days inside the female reproductive system, so the intercourse should happen during ovulation or the five days before it.
- Next, the fertilized egg has to travel down the fallopian tube and implant in the uterus.
- Lastly, hCG levels must be detectable in the body. Only then will a home pregnancy test read positive.
When are hCG levels detectable?
Sometimes hCG reaches detectable levels before missing your period—but sometimes it doesn't, says Daniel Roshan, MD, an OB-GYN at Rosh Maternal-Fetal Medicine in New York City. Because hCG levels double every 48 to 72 hours, according to Dr. Roshan, taking a pregnancy test after missing your period gives you a greater likelihood of accuracy.
For those with irregular periods, a good rule of thumb is waiting three weeks after having sex before taking a home pregnancy test.
Most manufacturers recommend that home pregnancy tests be taken twice, since results may vary if you take a test too soon. This eliminates the likelihood of a false negative result.
Early Pregnancy Sympyoms
If you had unprotected sex, you should take a home pregnancy test if you experience early signs of pregnancy, including the following:
- Sore breasts
- Fatigue
- Nausea
- Bloating
- Frequent urination
- Implantation bleeding or cramping
- Mood swings
- Constipation
Are Home Pregnancy Tests Accurate?
Home pregnancy tests are about 99% accurate when used correctly and taken on or after the day of your expected period. It's possible to get false negative results (when you're actually pregnant but the test says you aren't). The most common cause is taking the test too early, but it can also happen if you don't follow instructions.
If you missed your period and it doesn't arrive after a few days, repeat the test or check with your health care provider, suggests Marra Francis, MD, a board-certified obstetrician and gynecologist. Irregular periods could be caused by illness, certain medications, low or excess body weight, excessive exercise, stress, or hormonal contraceptives.
Even rarer, it's possible to get false positive results (you're not pregnant but the test says you are). While false positives mainly happen to people taking fertility drugs, they can also be caused by an expired pregnancy test, recent miscarriage or abortion, pregnancy loss soon after implantation (chemical pregnancy), or ovarian tumors.
Here are some tips for increasing the accuracy of your pregnancy test:
- Check the pregnancy test's expiration date before using it.
- Test first thing in the morning, as the concentration of hCG in your urine is usually highest then.
- Don't chug liquids before taking a pregnancy test. Doing this can dilute hCG levels in your urine and lead to a false negative result.
- Some medications, like prescription fertility drugs, might mess up the pregnancy test. Your health care provider may recommend getting tested in the office for more promising results.
- Improper usage and exposure to sunlight may also lead to inaccurate results. Always use the pregnancy test according to instructions.
- Always read the test results within the recommended time frame.
My Pregnancy Test Is Positive—Now What?
If your test has a positive result and you've followed all of the steps correctly, it's safe to assume that you are, in fact, pregnant. The next step is calling a pregnancy care provider, who will likely schedule a prenatal appointment.
For many people, a pregnancy blood test is not needed to confirm the pregnancy, but your health care provider may want to schedule a first trimester ultrasound, depending on your health history and current medical status.
You should also start taking some prenatal vitamins as you await your appointment (though ideally you'd start taking them when trying to conceive). Pregnant people should also stop smoking and drinking, as well as limit their caffeine intake.
