Medically reviewed by Cordelia Nwankwo, MD
If you've recently had unprotected sex, it's common to wonder when you should test for pregnancy. The short answer: home pregnancy tests are most accurate when you take them after your period is late. Generally, you can take early-detection pregnancy tests eight days after conception. However, experts suggest that you'll get your most accurate test results when you take a test 10 to 14 days after unprotected sex.
Pregnancy tests work by detecting the presence of human chorionic gonadotropin (hCG)—a hormone that people with female reproductive systems produce after conception and implantation. It can take up to two weeks after unprotected sex for your body to produce enough hCG for the test to detect the hormone properly.
Keep in mind: taking a pregnancy test too soon can cause a false negative. Here's everything you need to know about when to test for pregnancy and how to avoid getting an inaccurate test result.
If you want to prevent pregnancy after having unprotected sex, consider emergency contraception. Various choices include over-the-counter or prescription pills and intrauterine devices (IUDs).
Why You Should Take A Pregnancy Test
You might consider taking a pregnancy test if you have a reason to believe that you may be pregnant. These reasons may include:
Having unprotected sex
Breaking a condom during sex
Experiencing pregnancy symptoms such as nausea or fatigue
Trying to get pregnant and wanting to confirm conception
When Should You Take a Pregnancy Test?
You will get the most reliable and accurate results if you wait to test for pregnancy if your period is late. If you don’t want to wait that long (or you don’t have regular periods), wait at least 10-14 days after unprotected sex to take the test.
To maximize the accuracy of a pregnancy test, it’s best to take the test first thing in the morning. Generally, if you're using an at-home pregnancy test, you'll likely be peeing on a stick to get your results. That said, it's best to use your first urine of the day for the pregnancy test.
Human chorionic gonadotropin (hCG) levels are the most detectable when urine is concentrated (not diluted). Your urine concentration is at its highest after a period of not drinking many fluids and not using the bathroom—which generally occurs while you sleep throughout the night.
What Can Affect Test Results?
Home pregnancy tests can be up to 97% accurate if you use them correctly. To get the most reliable results, read and follow all directions that come with your test.
But, sometimes it's possible to get a false negative or positive. The most common reasons for inaccurate results include:
Diluted urine: Drinking too much water or other liquids before taking the test can dilute the urine and result in a false negative.
Blood in the urine: Blood in the urine can cause a false positive.
Testing too early: Testing before the body produces enough hCG can result in a false negative.
Improper test use: Improper test use could mean not following the pregnancy test instructions properly, using an expired or damaged test, or checking the result window too early or too late.
Medications or blood transfusions: While not common, some medications can cause a false positive. This is not an exhaustive list, but medications that can affect your test results include fertility medications, certain antidepressants, and blood transfusions.
Chemical pregnancy: A chemical pregnancy occurs when a fertilized egg fails to implant in the uterus. This can result in a positive pregnancy test followed by a miscarriage. Testing too early increases the risk of a false positive from a chemical pregnancy.
Symptoms of Early Pregnancy
Early pregnancy symptoms can begin as early as one week after conception. However, some people do not have symptoms for several weeks. If you do experience early pregnancy symptoms, you may notice the following changes to your health:
Nausea and vomiting
Swollen or tender breasts
Not all pregnant people experience symptoms, especially during the early stages of pregnancy. Symptoms also vary from person to person. Additional symptoms that you might have in the first trimester of your pregnancy include:
However, it's important to note that pregnancy symptoms can sometimes mimic symptoms of other health conditions and lifestyle changes. Factors that can cause pregnancy-like symptoms and produce changes to your health include:
Stress, depression, or anxiety
Hormonal changes or imbalances
Excessive changes in weight
Food poisoning or stomach illnesses
A Quick Review
If you think you may be pregnant or recently had unprotected sex, it's common to want to test for pregnancy to learn about your status. You will get the most reliable test results after you miss your period. Your body does not make enough hCG (the hormone pregnancy tests detect) until 10-14 days after conception. If you don’t want to wait until you have missed your period, experts advise you to wait roughly two weeks after unprotected sex to test for pregnancy.
To ensure the most accurate pregnancy test results, it's also important to:
Check the expiration date of the pregnancy test
Follow the pregnancy test directions carefully (including how to take the sample and how long to wait for results)
Avoid drinking large amounts of fluids before taking the test (take it first thing in the morning if possible)
Consult with a healthcare professional if you have concerns that a medication or illness is causing a false-positive result
If you think you are pregnant and get a negative result, consider testing again after you miss a period or after two weeks of having unprotected sex.
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Read the original article on Health.