This is the moment you’ve been waiting for — awkwardly squatting over your toilet in preparation for the most important pee of your life, in pursuit of the answer to the question drowning out all other thoughts: “Am I pregnant?”
Taking a pregnancy test can be simultaneously exhilarating and exasperating. There’s a lot riding on those two little lines, so you want to make sure you have ample urine to give, follow the instructions to a T, and remain calm while waiting for your destiny to reveal itself.
But before you even release that fateful first droplet, you have to pick out a pregnancy test from a drugstore shelf chock full of confusing options. Should you go with a pink dye, blue dye, or digital test? Which ones are best — and how do they work? Let’s break it down.
There are a plethora of brands and types of pregnancy tests, and it can be daunting for a first-timer to wade through the options. While there are some distinguishing factors, all home pregnancy tests work the same way — by checking for human chorionic gonadotropin (hCG) in your urine.
Over-the-counter pregnancy tests are either digital or dye-based. Both blue and pink dye tests employ a chemical reaction that activates a color change on a designated strip to display a line or plus sign when hCG is detected in urine.
Digital tests will display a reading notifying you if you are “pregnant” or “not pregnant” depending on hCG.
The consensus online among frequent testers is that pink dye tests are the best overall option.
Many people believe that, compared to their blue counterparts, pink dye tests are less prone to getting an evaporation line. This faint, colorless line can make reading a result more confusing, and deceive someone into thinking they have a positive result, when, in fact, the test is negative.
Be sure to read the boxes before you buy; dye tests have different levels of sensitivity to hCG. The higher the sensitivity, the more likely a test will detect a pregnancy earlier.
Most pink dye tests have a hCG threshold of 25 mIU/mL, meaning that when it detects at least that amount of hCG in your urine, it will produce a positive result.
Pink dye tests can also range in price point, with brand names like First Response costing a bit more. There are lots of equally effective generic options on the shelves, and you can order inexpensive test strips online in bulk — if you plan to check every day. (We’ve been there, and won’t judge.)
If directions are properly followed, most pink dye tests are extremely accurate when used on or after the first day of a missed period.
Ultimately, it comes down to personal preference. If you want to read the words “pregnant” or “not pregnant,” go with a digital option. Prefer to test early and frequently? Consider ordering strips. Want an ergonomic wand you can pee directly on? A dye stick will do the trick.
And if you’re worried about potential evaporation lines causing confusion, stick with a pink dye test.
Pregnancy tests work to find human chorionic gonadotropin (hCG) in your urine. This hormone is produced approximately 6 to 8 days after a fertilized egg implants itself in the uterine wall.
The hCG in your body doubles every few days, so the longer you wait to test, the more likely the result will be accurate.
While some tests may be able to detect hCG as early as 10 days after conception, most doctors agree that it’s best to wait until after a period is missed to take a test. By this point, most pregnancy tests will yield a 99 percent rate of accuracy.
There are various types of pregnancy tests that utilize dye: sticks that you can pee directly on, cassettes that include a dropper for precise urine application, and strips that you can dip into a cup of urine.
Dye tests tend to be more sensitive to hCG, making them better options for earlier use. While pink dye tests win for internet popularity, they boast a similar sensitivity to blue dye options. Generally, most dye tests detect hCG in urine at levels between 25 mIU/mL and 50 mIU/mL.
Digital tests, on the other hand, are less sensitive and may require more hCG — which is why you should wait until you’ve actually missed your period to try this type of test.
Most dye tests are very accurate when used properly. But in order to get the right reading, it’s critical you follow the instructions.
Many dye tests feature designated spaces for two separate lines: a control line and a test line. The control line always appears, but the test line only emerges if there is hCG present in your urine.
Unfortunately, sometimes, the evaporation of urine used to take the test will create a very faint second line in the test area. This generally happens after the instructed wait time (typically 3 to 5 minutes) has passed. It can be confusing and deceiving, and lead a tester to believe the result is positive — even though it is not.
Consider setting a timer, so you don’t let extra minutes pass before checking the results — in the event you haven’t been staring at the stick the entire time. The longer you wait outside the instructed window of time, the more likely you are to see a perplexing evaporation line.
While an evaporation line can appear on a pink or blue dye test, many frequent testers on popular online pregnancy and fertility forums adamantly argue that blue tests are more prone to these deceptive shadows.
Furthermore, an evaporation line is more easily confused with a positive on a blue test, since its dull grayish imprint is similar to that of a light blue line.
Determining whether a test line is truly positive or the result of evaporation can cause distress. Look at the line carefully — it may not be as bold as the control line, but as long as there is a distinct color to it, it’s considered positive.
If it’s gray or colorless, it’s most likely an evaporation line. When in doubt, test again.
A positive pregnancy test result without an actual pregnancy is considered a false positive.
However, false negatives are more common than false positives. If you get a negative result, but still believe you’re pregnant, you can always test again. If you’re testing before a missed period, give it a few more days; it’s possible the hCG is just not yet detectable in your urine.
Remember to always try to use your first morning urine when testing, as that’s when hCG is at its highest concentration.
Getting a false positive test result can be devastating to eager would-be parents. Here are a few reasons you may get a false positive.
- Evaporation lines. As discussed, an evaporation line, created after urine evaporates on the test strip, can cause a tester to misread the results of a pregnancy test. Following the test’s instructions and reading results within the provided time frame can help to avoid this potentially heartbreaking blunder.
- Human error. Home pregnancy tests may boast their accuracy, but human error is a fact of life. Check the expiration date of your test, and thoroughly read the instructions for specific directives and time limits.
- Medications. Certain medications can lead to a false positive, including some antipsychotics, anticonvulsants, antihistamines, and fertility drugs.
- Chemical pregnancy. A false positive can happen when a problem with the fertilized egg leaves it unable to attach to the uterus and grow. Chemical pregnancies are rather common, but often go undetected, as you may get your period before you’d even suspect that you’re pregnant and test.
- Ectopic pregnancy. When a fertilized egg implants itself outside the uterus, the result is an ectopic pregnancy. The embryo, which is not viable, will still produce hCG, resulting in a false positive test result. Although this can’t result in a healthy pregnancy, it is a health risk. If you suspect an ectopic pregnancy, seek medical care.
- Loss of pregnancy. The hormone hCG can be detected in blood or urine for weeks following a miscarriage or abortion, resulting in a false positive pregnancy test.
Taking a pregnancy test can be stressful. Understanding the way they work, when to use them, and how to mitigate potential error can help make the whole pee-and-wait process a little less nerve-wracking.
Whether you choose to use the more popular pink dye variety, or opt for a blue dye or digital test, remember to follow the directions and read the results within the provided time frame. Good luck!