Maybe you can’t wait to have a baby. Or maybe that’s the last thing you’re hoping for. Show
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy Either way, if you think you might be pregnant, you need to know for sure. But what are the odds a positive pregnancy test might be wrong? “Home urine pregnancy tests are pretty reliable,” says Ob/Gyn Jonathan Emery, MD. “But there are some reasons you might get a false-positive result.” Dr. Emery explains when and why a pregnancy test might give a false positive — and what you can do to make sure the stick doesn’t lie. How do pregnancy tests work?When you get pregnant, your body produces a hormone called human chorionic gonadotropin, or hCG. Home pregnancy tests look for that hormone in your urine. If hCG is present, you should get a positive test result when you pee on a stick. But hCG levels start out very low and increase over time. If you take the test too soon after conceiving, it might say you’re not pregnant when you really are. In other words, timing can lead to a false negative. But what about a false positive? False positives aren’t super common, Dr. Emery says. But they’re not impossible. Some potential causes include: Early miscarriage or chemical pregnancyYou took a pregnancy test and got two lines. (Positive!) But a few days later, your period arrived in force. What gives? The most common reason this happens is an early pregnancy loss, also known as a chemical pregnancy. In this case, the test was accurate — there was a pregnancy, but it wasn’t a viable one, Dr. Emery explains. “It’s not technically false since a very early pregnancy did occur,” he says. “But this is the most common reason that a pregnancy test might appear to have been false.” Fertility medications“A lot of fertility treatments involve taking hCG injections,” Dr. Emery says. If you’ve been taking fertility medications, that hCG might still be floating around your system. That could trigger a positive pregnancy test, even if you’re not pregnant. To avoid that mix-up, wait at least two weeks after your last hCG injection to take a home pregnancy test, he says. Recent pregnancyIf you were recently pregnant, you might still have leftover hCG in your system. After childbirth, miscarriage or treatment for ectopic pregnancy, the hormone can remain in your body for up to four to six weeks, Dr. Emery says. “That could lead to a positive pregnancy test when your body just hasn’t cleared the hCG yet.” User errorHome pregnancy tests aren’t especially hard to use. But you still have to pay attention since a mistake can lead to incorrect results. If you wait too long to read the results, for example, or use more drops of urine than the test calls for? You might want to take the answer with a grain of salt. “If you don’t follow all the instructions, any results — positive or negative — could be false,” Dr. Emery says. Pregnancy test accuracy: How to get results you can trustLuckily, false positives are rare. And there are steps you can take to make sure your home pregnancy test gives you results you can trust.
Home pregnancy tests are inexpensive, private and quite reliable, Dr. Emery adds. “People often don’t believe what they’re seeing. But if you’ve used the test correctly and done it at the right time, it’s probably true.” SummaryRead the full fact sheet
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From other websitesContent disclaimerContent on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional. The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances. The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Is it possible to have a positive blood test and not be pregnant?Chemical pregnancy
It's possible to have a positive pregnancy test even if you aren't technically pregnant. This is called a false positive. It's sometimes caused by a chemical pregnancy. A chemical pregnancy occurs if a fertilized egg, known as the embryo, is unable to implant, or grow, very early on.
How accurate is a positive blood pregnancy test?This blood is sent to a laboratory for testing. The results of most blood pregnancy tests take at least a couple of days. The laboratory then advises the doctor of the result. Blood test results are about 99 per cent accurate and can detect lower amounts of hCG than urine pregnancy tests.
What can cause a falseMost of these false-positive results are due to interference by non-human chorionic gonadotropin substances (especially human luteinizing hormone and anti-animal immunoglobulin antibodies) and the detection of pituitary human chorionic gonadotropin.
Can you have a falseABSTRACT: Clinically significant false-positive human chorionic gonadotropin (hCG) test results are rare. However, some individuals have circulating factors in their serum (eg, heterophilic antibodies or nonactive forms of hCG) that interact with the hCG antibody and cause unusual or unexpected test results.
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