What You Need to Know About At-Home Pregnancy Tests

You likely have many questions about at-home pregnancy tests, like “How soon after unprotected sex can I test for pregnancy?” or “How accurate will the results be?” and probably a dozen others.

Lauren Kauvar, MD, a Littleton OB/GYN with AdventHealth Medical Group OB/GYN at Littleton, is here to answer some of the most common questions about home pregnancy tests, including how they work and whether they’re accurate in certain situations.

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How soon after unprotected sex can I take a pregnancy test?

“For most at-home pregnancy tests, the best time to test is at the time of a missed period,” Dr. Kauvar says. “There are a few tests on the market that claim to detect pregnancy a few days before that, but overall, testing too early can lead to false negatives.”

Pregnancy tests work by detecting human chorionic gonadotropin (hCG), a hormone that rises in early pregnancy. The earlier you test, the lower your hCG levels may be — potentially leading to an inaccurate result. If you test early and get a negative result, Dr. Kauvar recommends waiting a week and testing again if your period still hasn’t started.

Can twins cause a false negative pregnancy test?

There’s a common myth that carrying twins can cause a false negative pregnancy test, but Dr. Kauvar says that’s not the case. “A twin pregnancy should not cause a false negative,” she says. “In fact, hCG levels tend to be higher in twin pregnancies, not lower.”

If you suspect you might be pregnant with twins but receive a negative test, it’s more likely you tested too early rather than the presence of multiple embryos. Several factors, like diluted urine or a less sensitive test, can contribute to false negatives. If you continue to experience pregnancy symptoms but receive negative test results, talk to your doctor for further evaluation.

Do pregnancy tests expire?

Yes, pregnancy tests expire, and using an expired test can affect the test’s accuracy.

“If a test is expired, it may not work properly and could give a false negative or false positive,” Dr. Kauvar says. Before taking a test, check the box for an expiration date to ensure reliable results.

Which drugs can cause a false positive pregnancy test?

Most drugs, like antibiotics, birth control and pain relievers, will not cause a false positive pregnancy test. However, some fertility treatments, such as those containing hCG, can cause a false positive. “If you’re undergoing fertility treatment, make sure to check with your doctor about when to test,” Dr. Kauvar says.

In rare cases, certain medical conditions such as ovarian cysts, trophoblastic disease and some cancers can cause a false positive by producing hCG. If you receive an unexpected positive result and aren’t undergoing fertility treatments, follow up with your doctor for confirmation.

If a pregnancy test is negative today, can it be positive tomorrow?

Yes, it’s possible for a test to be negative today and positive tomorrow because hCG levels rise over time. “If you test too early, your body may not have produced enough hCG for detection,” Dr. Kauvar says. If your test is negative but you still haven’t gotten your period, we suggest waiting a few days and testing again. “I wouldn’t recommend testing every single day. That can create unnecessary anxiety,” she says. “But if your period hasn’t started in a week, take another test.”

It's also important to regulate your fluid intake before testing. Colorado’s high altitude can contribute to dehydration, which may affect urine concentration and the accuracy of pregnancy tests. Drinking a large amount of water before testing could dilute your urine and lead to a false negative. Staying properly hydrated throughout the day, rather than consuming excessive fluids right before taking a test, can help ensure the most accurate results.

How accurate are at-home pregnancy tests?

When used correctly, home pregnancy tests are more than 99% accurate. “The most important thing is to follow the instructions carefully,” Dr. Kauvar says. “Using the first-morning urine can sometimes improve accuracy, but overall, home urine tests are just as reliable as the ones we use in the office.”

Not all pregnancy tests display results in the same way. Some tests use lines that may appear faint, while others change color or provide digital results. Understanding how to read the specific test you’re using is crucial to interpreting the results correctly. Follow the manufacturer’s instructions closely to avoid confusion, especially with evaporation lines that can sometimes be mistaken for a positive result.

What should I do if I get a positive result?

If you get a positive pregnancy test, your next step is to call your Littleton OB/GYN to schedule a confirmation visit. “We typically schedule a new OB appointment two to four weeks after a positive home test so we can visualize the pregnancy on ultrasound,” Dr. Kauvar says.

Visualizing the pregnancy means using an ultrasound to confirm that the pregnancy is developing in the right location (inside the uterus) and to check for viability, such as detecting a heartbeat. This is an essential step in ruling out complications such as an ectopic pregnancy, which occurs when a fertilized egg implants outside the uterus and requires medical attention.

If you have a history of miscarriage or ectopic pregnancy, your doctor may want to see you sooner to ensure early monitoring and appropriate care.

What if I have pregnancy symptoms but keep testing negative?

If you’re experiencing pregnancy symptoms but your test results remain negative, there could be several reasons. “Testing too early, an irregular cycle or even a hormonal imbalance could be at play,” Dr. Kauvar says. Other possible causes include stress, thyroid disorders, polycystic ovary syndrome (PCOS) or perimenopause, all of which can cause hormonal shifts that mimic pregnancy symptoms, such as nausea, breast tenderness, fatigue and bloating.

Dr. Kauvar recommends testing once a week for up to four weeks if your period hasn’t started. “If you still haven’t had a period after a month of negative tests, it’s time to come in for an evaluation,” she says.

Does the brand or cost of the test matter?

The short answer is no. “There’s no difference between a home pregnancy test and the one we use in the office,” Dr. Kauvar explains. “There’s no need to spend extra money on fancy digital tests. Just make sure your test is not expired, and be sure to follow the directions.” All FDA-approved home pregnancy tests work the same way, whether they display results as lines or digitally spell out “pregnant” or “not pregnant.”

“The only additional test we can do is a blood test, which allows us to detect pregnancy at an earlier stage than urine tests,” she says. However, blood tests are typically reserved for those undergoing fertility treatments, people with a history of miscarriage and those with a medical need for early detection.

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How to Confirm Your At-Home Pregnancy Test

Home pregnancy tests are a convenient and reliable way to check for pregnancy, but the timing of the test and following instructions carefully are key to getting an accurate result. Following up with a medical professional is essential for confirming a positive test result and addressing concerns about irregular cycles or persistent negative tests.

We’re Here for You Every Step of the Way

Schedule an appointment with AdventHealth Medical Group OB/GYN at Littleton today by calling our front desk at Call720-922-6240. Our experienced team is here to provide you with expert care at every step of your pregnancy journey.