Are Pregnancy Tests Always Right? 5 Factors To Consider
By Abi Berwager Schreier | Originally Published October 6 on Romper | Featuring Dr. Sherry Ross
Taking a pregnancy test is stressful business, whether you’re trying to conceive or trying to prevent a pregnancy. While it seems like it should be a simple yes or no, there is a lot to contend with when taking those tests, and you want to know for sure with 100 percent certainty. But are pregnancy tests always right? Turns out, there are some factors to consider.
If you’re unsure of the results of your pregnancy test, experts say you’ll want to consider if you’re taking the test too early, if you’re taking fertility drugs that could affect the results, if your test is expired, and even if any medications you’re on could make a difference. Some tests may even provide false information more than others, like the blue dye tests, according to Dr. Sherry Ross, OB-GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California. She tells Romper that these blue dye tests are harder to interpret because it works based on the evaporation of your pee, and that line can be colorless, which is often confused as a positive result. It looks like a shadow, according to Ross.
So perhaps not all pregnancy tests are created equal. But what about the pink dye tests or even digitals? Is there a chance they can be wrong? Whether you got a double line and didn’t want them, or you got a single line and was hoping for a double, you obviously want to be 100 percent sure of your test results. What factors can constitute a false reading on even the best of pregnancy tests?
1. Testing Too Early
In an email interview with Romper, OB-GYN Gerardo Bustillo of Orange Coast Memorial Medical Center in Fountain Valley, California, says false negative tests are indeed possible. “The most common cause is performing the test too soon after conception, especially with a history of irregular cycles or an uncertain last menstrual period,” he says. So when is it safe to test? “Such patients should wait at least two weeks from a sexual act before using a home pregnancy test. Rarely, a false-negative result can occur with very high hCG levels, which can be seen with gestational trophoblastic disease, a rare group of pregnancy-related tumors.”
2. HCG Interference
According to Bustillo, even though false positive tests are uncommon, they are possible. “Possible reasons include operator error, interference from hCG administered as part of infertility treatment or in certain diet programs, tumors secreting hCG, and when hCG is secreted by the pituitary gland, typically in perimenopausal women.” Wouldn’t this be the very worst thing ever? But like Bustillo said, it’s very uncommon, so don’t fret and enjoy that positive test until you get to your first doctor’s appointment and they prove otherwise.
3. Choice Of Test
It’s pretty common knowledge that blue dye tests aren’t always super accurateand tend to give a lot of false positive, but Bustillo notes that each test actually varies in their accuracy, too. “More expensive tests are not necessarily superior. A recent medical study showed that the most accurate tests were the First Response Manual and First Response Gold Digital Device,” he says.
4. Expired Tests
Much like medications, home pregnancy tests lose their “potency” and accuracy when they expire. “All pregnancy tests last approximately two to three years once produced. Typically, the less expensive pregnancy tests have a shorter shelf life,” Bustillo says.
While Bustillo says food doesn’t affect results of home pregnancy tests, certain medications can. “As noted previously, some medications used in fertility treatments, as well as in certain diet regimens, can result in false-positive tests,” he says.
While blood and urine tests at the doctor are the most accurate, remember, most of the time, if you have two blazing dark lines on your home pregnancy test and you have a missed period, it’s pretty safe to say that you have an accurate positive pregnancy test in your hands. Like that Clearblue Digital commercial says, “It’s the most sophisticated piece of modern technology you’ll ever pee on.”