Pink Dye Pregnancy Tests Are Better Than Blue Dye Pregnancy Tests - Fact or Fiction?

Written by Kate Freeman. Reviewed by Dr. Phoebe Howells.

If you're new to the journey of trying to conceive (ttc), the excitement and anticipation of finally testing can be overwhelming. On the other hand, if you're no stranger to this ttc game, you're all too familiar with that awkward mix of emotions - excitement, nervousness, and frustration. The stakes are high, and all you desire are accurate results.

While the number of pregnancy test brands may not be vast, the types of tests available certainly are. You might have delved into the online world of forums and blogs, stumbling upon claims that pink-dye tests reign supreme (and by the way, we happen to use pink dye!). But beyond just wondering which brands use this dye, your main concern will be whether there's any truth to these assertions. Well, let's dive right into the heart of the matter!

Pregnancy Tests - How Do They Actually Work?

Before we even get into the pink vs blue dye debate, let's just explore how the tests work. All urine based pregnancy tests function in the same fundamental way. They detect the presence of a hormone called human Chorionic Gonadotropin (hCG). The release of hCG into the body occurs when an embryo successfully implants itself in the uterine wall. 

So, what does a positive pregnancy test look like? If we focus on analog tests, by which we mean tests which display results in lines, if hCG is detected the test will display two lines, showing a positive result. 

So Why Is There So Much Fuss Over Pink vs Blue Dye? 

This comes down to evaporation lines. After the designated wait time has elapsed, you may occasionally notice a faint, colourless line appearing on the pregnancy strip. This is referred to as an evaporation line. It can emerge when the test gets wet, the urine evaporates and leaves behind residue on the test strip. It tends to look like a colourless streak rather than an actual line, often referred to as a ‘squinter’ as they’re not immediately easy to see. 

Understanding Evaporation Lines

Blue-dye tests have garnered a reputation for producing blue evaporation lines. It remains uncertain whether these tests are genuinely more prone to evaporation lines or if the lines are more likely to be mistaken for a positive result, as a greyish evaporation line can resemble a blue positive line. The vast majority of the women we surveyed believe that tests using pink dye are a necessity as blue dye tests are renowned for leaving evaporation lines. 

How To Prevent Evaporation Lines

Evaporation lines usually appear when the test’s Instructions for Use have not been followed. However, if you continue to get evaporation lines then we suggest the following: 

  • Use your first urine of the day, as any hCG will be at its most concentrated at this time. This is especially important if you are testing before your expected period date. Should you wish to test later in the day, please ensure you haven’t drunk too much liquid in the hours before testing.
  • Instead of peeing directly onto the test, try peeing into a cup and dipping the test into the cup. Accidentally wetting the test too much whilst peeing on it can make a test invalid.
  • Check the expiry date of your tests.
  • Do not open the wrapper of your test until you’re ready to start testing, and do not use the test if the wrapper looks damaged or is torn. 
  • Store your tests at the temperature recommended on the packaging. For our tests, that’s between 4℃ - 30℃ .
  • And, most importantly, wait five minutes to check your results and ensure you read the results within 15 minutes in total. We highly recommend setting a timer for this as so many of us underestimate the length of time that has passed!
  • Consider using a test that works with pink dye only! 

The vast majority of the women we surveyed believe that tests using pink dye are a necessity as blue dye tests are renowned for leaving evaporation lines. 

We understand the preference for pink dye tests, but we’d stress that you should consider more than just the colour of dye used when picking a pregnancy test. Here are our top tips…

What Else Should I Consider When Buying a Pregnancy Test?

  • Test Sensitivity. Sensitivity of the test is ultimately more crucial than the dye colour given how common it is to choose to test as early as possible when ttc. Each home pregnancy test brand has a specific hCG level it is designed to detect. Once the hCG level reaches or exceeds this threshold, a positive result is obtained. So the sensitivity to hCG is important because one test could yield a negative result while another detects pregnancy. All brands should state on the box the hCG sensitivity level, however some brands don't make this clear. We’d encourage you to use as sensitive a test as is available if your preference is to test as early as possible.

The OVUM Early Detection Pregnancy Tests are ultra-sensitive and have the highest possible sensitivity of 10mIU/mL (based on WHO 4th International Standard 75/589). The test is more than 99% accurate in predicting pregnancy at three days before your expected period. At four days before your expected period, the test is 97% accurate, and at five days before your expected period, the test is 77% accurate. 

Number of days before expected period

Percent of Pregnant Women who get a Positive Result

0 (expected day of period)

> 99%


> 99%


> 99%


> 99%


> 97%


> 77%

As ever, it is super important to read the instructions carefully before use too. This will help to ensure the accuracy of your results, as factors such as waiting too long to read the result window and use of certain fertility drugs, amongst other factors, can affect the results. 

  • Ease of Use. By this we mean ‘how’ do you want to test. For most people, midstream tests are the preferred choice - no fuss, just hold the stick and pee on it. Traditionally at home pregnancy testing has always been done via urine, but lately, a wave of innovative alternatives have hit the market, including blood pin prick tests and saliva tests. They promise a different testing experience, steering away from traditional urine tests. While these novel methods may sound intriguing, it is vital you check what the confirmed sensitivity of these products are. If that information isn’t available on the website, make sure to ask them directly.
  • Genuine Support. Emotional support is a factor overlooked in this sector, but at Ovum we know that a negative result can hit hard. It can be an indescribable and all consuming pain when you are trying to conceive. To help with this, our pregnancy tests are sold with a 5 minute guided meditation from leading fertility mindset coach Alice Rose. By using the QR code laid out on our beautiful Instructions for Use, you can gain immediate access to the meditation. We hope this supportive and empowering tool helps to navigate this tough moment.
  • Value for Money. If you prefer to test as early as possible, this normally means you’ll get through a fair number of tests each cycle. Tests can get very expensive so a brand that recognises and respects that those who are ttc may test more and can offer value is crucial. This is why we include four tests per box at a price of £19. 
  • The Environment. With over 12.5 million used tests, foil wrappers and desiccants ending up in landfill each year the choices we make each day about single use disposable products can no longer be ignored. Ovum is the first brand to launch a 100% recyclable pregnancy test. Whilst no pregnancy test is currently recyclable in household recycling yet (this is something we are working on!), we offer the ability to recycle our product, using our FREEPOST envelope in each box of tests allowing you to post your used tests, wrappers and desiccants directly to our U.K recycling partner, Enval. Our product is also certified and registered with the rePurpose global waste reduction initiative. So for every product purchased, Ovum funds the removal of twice as much plastic from the environment as is produced to make the tests. 

Takeaways - Which is better; pink vs blue?

We prefer pink-dye tests to blue-dye tests, as they tend to cause less confusion with evaporation lines. But we would stress that the following factors are just as important when considering which pregnancy tests to buy whilst on your ttc journey…

When testing up to 5 days before your expected period with Ovum Early Detection Pregnancy Tests note that the test is 77% accurate. At 3 days before your expected period the test is 99% accurate. 

  • Consider the ease of use when picking a test. We much prefer midstream tests, no one wants the additional worry of trying to angle pee into a cup! 
  • Is there additional support available should you receive a negative test result? This might not feel relevant to you, but we know so many women who have found great solace and help by using the guided meditation available in our tests. Whilst we hope you never need it, knowing it’s there can be a big help.
  • Value for Money. If your preference is to test as early as possible and therefore more frequently, you’ll definitely care about value for money. This is exactly why we offer four tests per box at a price of £19.
  • Lastly don't forget the environment, by choosing Ovum you can rest assured  that no used tests will end up in landfill.  


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