How sensitive are early pregnancy tests?

How sensitive are early pregnancy tests?

I'm going to talk about big brand OTC tests, professional tests, and the cheaper tests that can be purchased online.

First, quoted from Medscape.com:
"Regular hCG is neither the principal nor the sole hCGrelated molecule present in urine on the first day of the missed period, as demonstrated in multiple studies.[5-8] Studies show that a mixture of hCGrelated molecules is present, principally hyperglycosylated hCG, with lesser amounts of regular hCG, and much smaller amounts of free beta-subunit and beta-subunit core fragment. In this study we mimic this mixture as closely as possible. Manufacturers of OTCPTs design their products strictly to measure regular hCG and sometimes also free beta-subunit. They also determine the sensitivity of their products using regular hCG. Not surprisingly then, most OTCPTs have much lower sensitivity for hyperglycosylated hCG and beta-core fragment.[2,8] Five of the products evaluated here (Clearblue Easy Earliest Results, CVS One Step, E.P.T., Eckerd One Step, and First Response Early Result) were previously evaluated using pure hCG.[3] Their analytical sensitivities were 12.5, 50, 25, 50, and 6.3 mIU/mL, respectively, quite different from the analytical sensitivities in the current study, which used urine samples much more closely mimicking those of the first day of a missed period[2,8]: 25, 100, 100, 100, and 6.3 mIU/mL, respectively. At four of the five tested concentrations the sensitivity was greatly reduced. Manufacturers need to make OTCPTs based on the real mixture of hCGrelated molecules present in urine at the time of pregnancy detection and to make clinically accurate and relevant sensitivity claims based upon detection of this mixture rather than just regular hCG, which is predominantly present alone in the later trimesters of pregnancy.[2,3,5-8]"

In other words, because most tests don't pick up a mix of hCG and its degradation products, they aren't as sensitive as they could be if they picked up multiple forms.

The test which they are talking about that detects 6.3mIU/mL is First Response Early Results. However, this varies widely due to the lack of quality control with First Response pregnancy test, especially recently. If they produce a line at these detection levels the lines are usually unbelievably faint, look like the gray antibody strip, and not really visible without photo editing tricks. For the price of First Response they are better left on the shelf, especially in recent months with all the false positives they've been giving.

As an example of the faint lines on the First response, from the top down are my OSOM, First Response Early Results, and Clear Blue Rapid Results from 10dpo or 6 days before my missed period. As you can see the First Response is much harder to see than the other two, and I had to photograph it a bunch of times before I got a pic you could see the line in.

Therefore, you are much better off using something like Pregmate hCG test strips that can pick up just 5miu according to results in a fertility forum I frequent, and they are extremely affordable. You can purchase 20 Pregmate hCG test strips on Walmart.com for under what a two pack of First Response test cost, and they are worth every penny.

This is my Pregmate test from just 9dpo. Yes, it's super faint, but it's there, and 9dpo evening's test was even more clear!

Pregmate is certainly one of the most sensitive early pregnancy tests you can get your hands on.


Typical over the counter tests

Davies et al / Clin Lab Med 23 (2003) 257–264:

"It is not uncommon for a woman to have a negative urinary home pregnancy test result around the time of her missed menstrual period but a positive serum hCG result when
assessed a few weeks later. This discrepancy may be due to the insensitivity of
a home or point-of-care pregnancy test. There also is a clear variance in the sensitivity of home
and point-of-care pregnancy test devices for detecting intact hCG and HhCG:
some tests poorly detect H-hCG (the key molecule in early pregnancy),
and others more efficiently detect H-hCG than intact hCG. The data from
Butler et al indicate that urine devices need to be formulated to optimally
recognize H-hCG."

This still holds true for the most part, but there are some tests that do detect HhCG accurately. Clearblue rapid and their Digital are two that do detect HhCG. You will likely get a positive on these tests before your missed period. Blue dye tests have earned a really bad rep, this is due the big pharmacy brands (think Walgreens, CVS) manufacturing cheap blue dye pregnancy tests that often don't preform properly. Clearblue is in a different category, if you develop a clearly visible blue + or || lines, you can be sure it's a good sign. If you use their digital and it says pregnant, you can trust that result. Not all blue dye tests are bad.


Options for over the counter sensitive pregnancy test are the typical pink dye tests. Pink dye test are usually pretty sensitive these days, most have a cutoff limit of 25miu, but will pick up at even lower levels. 

Some trusted types/brands in the TTC community are:

• Dollar Tree pregnancy tests, the cassette type that you use a dropper with
• Walmart's $.88 cent cassette
• Any generic midstream test with pink dye

Stay away from:

• The new EPT pink dye tests*
• Generic tests with blue result lines

*I purchased these when I was testing for this pregnancy, and they didn't function properly. The test strip completely flooded with urine, not matter how little was used. I actually wrote them a detailed email on how to fix this issue since I majored in Molecular Biology, and have worked in multiple studies with other lateral flow pregnancy tests. It's quite an easy fix, but I imagine they probably manufactured them in the hundreds of thousands, and be out quite a bit of money. Their response was "we will forward this to the right department" - that was roughly 6 months ago and they haven't changed their tests. I recommend you steer clear of EPT, for now.

Point of care tests

Point of care tests are made for in lab testing and health care professionals. They are generally very sensitive and detect levels of 10miu-20miu, but can show positive at even lower levels, even as low as 2miu for some such as the OSOM brand. Often times these test will be combo tests, meaning that they can be used for urine and used moderately complex for serum. Moderatly complex means that one must be trained properly to use lab equipment to centrifuge the serum from a blood sample, which translates to a lab technician. 

Usually the general public doesn't have access the these point of care tests, but with the internet we can find almost anything. It's usual for these test to be sold in large packs of 30-100 or more, and depending on the brand they can get pricey. However, if you compare the cost of them to your typical OTC pregnancy test you'll find that you get far more for your money. For instance, you can get a box of OSOM (you can see my OSOM testing pics here) pregnancy tests for about $45, there are 30 tests plus 5 for control. That's 35 tests for $40 plus shipping if you don't find free shipping. If you compare that to First Response tests you'd have to buy 15 boxes (2 tests in each box) for $8.99 (price at Target) to get 30 test, for a total cost of $134.85 plus whatever your state tax is. 

Now, I know you're thinking who needs 30 pregnancy tests?!  You'd be surprised how fast you can go through pregnancy test when you're TTC. It takes a fertile couple an average of 6 months to conceive with good timing. That leaves 5 months of possible testing. If you're unlike me, and practice good self control, you may only test if you miss your period. If that's the case, by all means only buy a test once you've missed a period. BUT keep in mind that without actually tracking your ovulation things can get quite wonky when you start TTC, and your cycle can end up throwing you for a loop, or loops. You might have a 28 day clockwork cycle only to start TTC and end up with cycles that fluctuate by 2-3 days. Which means you'll think your period is late, but it's not, you'll pay $10-$20+ dollars for two pregnancy tests in a pharmacy, only for the same thing to happen in a later cycle. 

My advice is buy a multi pack of cheap tests like the Pregmates I've linked above, that way you can test without worrying about wasting money if your cycle throws you for a loop. If you get a positive you can confirm it with a big brand test, if you'd like. Pregmates are just as sensitive, if not more sensitive than most of the lab urine tests, and they work great. Keep in mind they are dip tests, so you will need to collect a urine sample.


What I recommend

I recommend searching for some OSOM test cassettes if you want. If not, your best bet is Pregmates (linked above). Another option that I used was McKesson Consult hCG test cassettes a POC test, these were extremely sensitive too, but were prone to getting evaps. It's best to read the McKesson hCG tests before they start to dry, no later than 30mins after taking it. I purchased my McKesson tests on Walmart.com with free shipping. OSOM test need to be purchased from a medical supplier site, you can just do a quick web search for them and find may suppliers that list them.

Here are examples of these at 10 days post ovulation, or 6 days before my expected period:

OSOM Combo

Pregmate

McKesson Consult 10dpo FMU

I will add more info soon, this post is a work in progress.