How Do Pregnancy Tests Work (and Are They Accurate)?

how do pregnancy tests work

Wondering if you might be pregnant? Pregnancy tests are a convenient and reliable way to get a quick answer at home. But how exactly do they work, and can you trust the results? Let’s break it down.

The Science Behind a Pregnancy Test

Pregnancy tests detect a hormone called human chorionic gonadotropin (HCG). This hormone is produced by the cells that form the placenta, the organ that nourishes a developing baby, after a fertilized egg implants in the uterus. HCG production starts very early in pregnancy, usually around 6 days after fertilization.

Types of Pregnancy Tests

There are two main types of pregnancy tests:

  • Urine tests: These are the most common type and are readily available at drugstores, grocery stores, and online retailers. They come in various formats, including dip sticks, midstream tests, and digital tests. All urine tests work by directing your urine stream (pee) over a specific area on the test strip. This area contains antibodies that react with HCG if it’s present in your urine. The test results will appear on a display window on the test strip within a few minutes.
  • Blood tests: Blood tests are typically performed in a doctor’s office and can detect HCG earlier than urine tests, sometimes as early as 6-8 days after ovulation. This can be helpful if you suspect pregnancy very early on. Blood tests are also more precise than urine tests.

Accuracy of Pregnancy Tests

Home pregnancy tests, when used correctly and following the instructions provided, are highly accurate – around 99% accurate a week after your missed period. However, accuracy can be affected by several factors:

  • Timing: Taking a test too early, before your body has produced enough HCG, can lead to a false negative (negative result even though you’re pregnant). For the most reliable results, wait at least a week after your missed period. Some tests claim earlier detection, but these may be less accurate.
  • Following instructions: Make sure you read and follow the instructions on the test carefully. Improper use, such as not collecting enough urine or not waiting the full development time, can affect the results.
  • Test quality: Expired tests or those not stored properly may not function correctly.

What to Do After Your Test

If your pregnancy test is positive, congratulations! This is an exciting time, but it’s also normal to have many questions. The Women’s Resource Medical Centers of Southern Nevada can help you navigate your next steps.

We offer free pregnancy confirmation and ultrasounds to verify a healthy pregnancy. Our counselors can provide emotional support and information about your options, including parenting resources and adoption information. We’re here for you, no matter what you decide.

If your pregnancy test is negative, but you’re still concerned about the possibility of pregnancy, or if you have questions about birth control options, our center can also help.

Don’t Wait!

If you are in the Las Vegas area and suspect you might be pregnant, schedule an appointment online for a free pregnancy test. Don’t wait to get the answers you need. We’re here to support you on your journey.