How soon can you take a first response pregnancy test

4.0 out of 5 stars FRER sensitivity - checked with precise HCG concentrations
Reviewed in the United States on June 4, 2017

I decided to post some data about this FRER sensitivity for those of you who are like me wonders how the test reflects the actual HCG concentrations. I made serial dilutions of human recombinant HCG (Novarel), that I had some leftovers of after my IVF cycle. The dilutions were made with lab pipets, so the concentration should be pretty precise, and in the appropriate buffer (sorry for the details, that was my husband's urine) to model the amount of HCG in the urine for the test. Here are results (see photos attached too).At 5 mU/ml, which is below the threshold of 6 mU/ml ( the sensitivity, claimed by the brand), the test is very-very faint. However, I would consider it positive, because just husband's urine only gives no second line at all (I do not have photo for this, we did it some time ago with our first unsuccessful transfer, when I had chemical pregnancy). 5 mU/ml in your first morning urine is equal about 10-15 mU/ml in blood, so this is comparable to 5-4 days before your missed period. Also, compare the 5 mU/ml results with my actual results for 8 days post transfer of 6-day blastocyst (last picture), two days later at 10dpt I had blood beta-HCG level of 38.At 20 mU/ml we can see clear positive results. This is HCG level that you will have at your first day of missed period, and equals to about 40-60 mU/ml of beta-HCG in blood.And only at 100 mU/ml we see the second line at the same brightness as the control line. I would say at this HCG level the FRER test reaches it's saturation point.Also, I found out that you may use LH tests (used for ovulation detection) instead of HCG for the early results. LH tests are very sensitive, looks like even more sensitive than FRER (you can see how much darker the test line is for the 5 mU/ml sample). I could not find an information about what subunit of LH these tests are detecting, my understanding it is beta-subunit of LH which is nearly identical in structure to beta-subunit of HCG. Beta-HCG, however, has about 30 additional amino acids, so home pregnancy tests designed to pick up beta-HCG only, while home ovulation tests will pick up both. After ovulation and during pregnancy LH levels are down, so in my opinion you can easily use you LH leftover test to monitor HCG levels, at least to see how it doubles, for example.Another observation for FRER, these tests tend to get darker with time. If your HCG levels are expected to be below or around the threshold (like day 6 post IVF transfer or so), and the test line does not show up, I suggest you keep the test for another 24 h and you may see faint positive later.For those users, who claim about "false" positive FRER results. As my experiments with my husband's urine proved, if you do not have HCG, the test will be clear negative - no test line at all, only control line. If you see faint positive, which lately with another test disappeared, or if your period came, that means you had so called chemical pregnancy. It might be devastating, I understand, we had a chemical with our first failed IVF cycle. But this is a drawback of using very sensitive test, so just be prepared.To summarize my experiment: FRER is very sensitive, it shows faint positive even below claimed threshold, however good positive results are at about 20 mU/ml, or your first day of missed period. I give only 4 stars for these tests because of the idiotic curved handle - it is completely unnecessary design, makes it difficult to lay flat, and takes more space in the drawer if you want to keep the used test for future reference.

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Reviewed in the United States 🇺🇸 on June 4, 2017

I decided to post some data about this FRER sensitivity for those of you who are like me wonders how the test reflects the actual HCG concentrations. I made serial dilutions of human recombinant HCG (Novarel), that I had some leftovers of after my IVF cycle. The dilutions were made with lab pipets, so the concentration should be pretty precise, and in the appropriate buffer (sorry for the details, that was my husband's urine) to model the amount of HCG in the urine for the test. Here are results (see photos attached too).

At 5 mU/ml, which is below the threshold of 6 mU/ml ( the sensitivity, claimed by the brand), the test is very-very faint. However, I would consider it positive, because just husband's urine only gives no second line at all (I do not have photo for this, we did it some time ago with our first unsuccessful transfer, when I had chemical pregnancy). 5 mU/ml in your first morning urine is equal about 10-15 mU/ml in blood, so this is comparable to 5-4 days before your missed period. Also, compare the 5 mU/ml results with my actual results for 8 days post transfer of 6-day blastocyst (last picture), two days later at 10dpt I had blood beta-HCG level of 38.

At 20 mU/ml we can see clear positive results. This is HCG level that you will have at your first day of missed period, and equals to about 40-60 mU/ml of beta-HCG in blood.

And only at 100 mU/ml we see the second line at the same brightness as the control line. I would say at this HCG level the FRER test reaches it's saturation point.

Also, I found out that you may use LH tests (used for ovulation detection) instead of HCG for the early results. LH tests are very sensitive, looks like even more sensitive than FRER (you can see how much darker the test line is for the 5 mU/ml sample). I could not find an information about what subunit of LH these tests are detecting, my understanding it is beta-subunit of LH which is nearly identical in structure to beta-subunit of HCG. Beta-HCG, however, has about 30 additional amino acids, so home pregnancy tests designed to pick up beta-HCG only, while home ovulation tests will pick up both. After ovulation and during pregnancy LH levels are down, so in my opinion you can easily use you LH leftover test to monitor HCG levels, at least to see how it doubles, for example.

Another observation for FRER, these tests tend to get darker with time. If your HCG levels are expected to be below or around the threshold (like day 6 post IVF transfer or so), and the test line does not show up, I suggest you keep the test for another 24 h and you may see faint positive later.

For those users, who claim about "false" positive FRER results. As my experiments with my husband's urine proved, if you do not have HCG, the test will be clear negative - no test line at all, only control line. If you see faint positive, which lately with another test disappeared, or if your period came, that means you had so called chemical pregnancy. It might be devastating, I understand, we had a chemical with our first failed IVF cycle. But this is a drawback of using very sensitive test, so just be prepared.

To summarize my experiment: FRER is very sensitive, it shows faint positive even below claimed threshold, however good positive results are at about 20 mU/ml, or your first day of missed period. I give only 4 stars for these tests because of the idiotic curved handle - it is completely unnecessary design, makes it difficult to lay flat, and takes more space in the drawer if you want to keep the used test for future reference.

4.0 out of 5 stars FRER sensitivity - checked with precise HCG concentrations
By Karelia on June 3, 2017

I decided to post some data about this FRER sensitivity for those of you who are like me wonders how the test reflects the actual HCG concentrations. I made serial dilutions of human recombinant HCG (Novarel), that I had some leftovers of after my IVF cycle. The dilutions were made with lab pipets, so the concentration should be pretty precise, and in the appropriate buffer (sorry for the details, that was my husband's urine) to model the amount of HCG in the urine for the test. Here are results (see photos attached too).

At 5 mU/ml, which is below the threshold of 6 mU/ml ( the sensitivity, claimed by the brand), the test is very-very faint. However, I would consider it positive, because just husband's urine only gives no second line at all (I do not have photo for this, we did it some time ago with our first unsuccessful transfer, when I had chemical pregnancy). 5 mU/ml in your first morning urine is equal about 10-15 mU/ml in blood, so this is comparable to 5-4 days before your missed period. Also, compare the 5 mU/ml results with my actual results for 8 days post transfer of 6-day blastocyst (last picture), two days later at 10dpt I had blood beta-HCG level of 38.

At 20 mU/ml we can see clear positive results. This is HCG level that you will have at your first day of missed period, and equals to about 40-60 mU/ml of beta-HCG in blood.

And only at 100 mU/ml we see the second line at the same brightness as the control line. I would say at this HCG level the FRER test reaches it's saturation point.

Also, I found out that you may use LH tests (used for ovulation detection) instead of HCG for the early results. LH tests are very sensitive, looks like even more sensitive than FRER (you can see how much darker the test line is for the 5 mU/ml sample). I could not find an information about what subunit of LH these tests are detecting, my understanding it is beta-subunit of LH which is nearly identical in structure to beta-subunit of HCG. Beta-HCG, however, has about 30 additional amino acids, so home pregnancy tests designed to pick up beta-HCG only, while home ovulation tests will pick up both. After ovulation and during pregnancy LH levels are down, so in my opinion you can easily use you LH leftover test to monitor HCG levels, at least to see how it doubles, for example.

Another observation for FRER, these tests tend to get darker with time. If your HCG levels are expected to be below or around the threshold (like day 6 post IVF transfer or so), and the test line does not show up, I suggest you keep the test for another 24 h and you may see faint positive later.

For those users, who claim about "false" positive FRER results. As my experiments with my husband's urine proved, if you do not have HCG, the test will be clear negative - no test line at all, only control line. If you see faint positive, which lately with another test disappeared, or if your period came, that means you had so called chemical pregnancy. It might be devastating, I understand, we had a chemical with our first failed IVF cycle. But this is a drawback of using very sensitive test, so just be prepared.

To summarize my experiment: FRER is very sensitive, it shows faint positive even below claimed threshold, however good positive results are at about 20 mU/ml, or your first day of missed period. I give only 4 stars for these tests because of the idiotic curved handle - it is completely unnecessary design, makes it difficult to lay flat, and takes more space in the drawer if you want to keep the used test for future reference.

Reviewed in the United States 🇺🇸 on October 1, 2022

Accurate, easy to use and easy to read.

Reviewed in the United States 🇺🇸 on September 20, 2022

Definitely accurate I’m 32 weeks now

Reviewed in the United States 🇺🇸 on September 15, 2022

This works! I’m pregnant!

Reviewed in the United States 🇺🇸 on September 1, 2022

It came ahead of schedule, easy to use and accurate. Per my girl

Reviewed in the United States 🇺🇸 on August 27, 2022

Convenient to buy online when you can’t/don’t want to leave the house. Easy to use, easy to read, great quality.

Reviewed in the United States 🇺🇸 on June 29, 2021

I don’t recommend driving yourself insane (trying to read faint lines too early). But if you insist on it, here’s what I wish I’d found when I was driving myself crazy!:

In this study (https://pubmed.ncbi.nlm.nih.gov/16295647/), the FRERs detected levels as low as 6.3 mIU/mL. <5 mIU/mL is considered a negative blood test, just to clarify.

I did a natural (no meds) FET cycle with an hCG trigger (Ovidrel). I tested out the Ovidrel. Negative at 4dp5dt (4 days post 5 day transfer and 10 days post Ovidrel 250 mcg).

On day 5 after the transfer of a 5 day old non-expanded blast (5dp5dt or about 10dpo - that’s 10 days post ovulation), nothing appeared on the test with first morning urine between the recommended 3-10 min window read. HOWEVER, a few hours later (I know, I know) I thought I saw something. This is where I drove myself insane.

Can deposits from the urine settle on a test line after 10 minutes? Yeah, sure. I don’t really know, because I’m not a chemist nor expert in these tests. I’ve just taken hundreds of them 🤷‍♀️ I also still have all of my positive tests (and the negatives leading up to the days before the positive ones) from 10 years ago. None of them have changed (from negative to positive or the reverse, acquired a false line, nothing).

I dabble in photography as a side hobby and understand photo metadata (from learning PhotoShop) well enough to know that I am not manipulating negative tests to positive ones simply by editing pictures of my early tests. I am quite simply just using tools to visualize certain aspects of the existing data of the picture.

These test have a phenomenal ability at low-level reads! Albeit, visually difficult to the naked eye at these extremely low levels.

The best thing I can recommend (again, if you insist on making yourself crazy too early in the game) is to take a close look (and maybe even a picture-I did not) of the test BEFORE peeing on it. I did notice incredibly faint grayish test lines (but not on the control part) on my tests before I took them. And I struggled to visualize if my early faint positives were actually that gray line or pink (hence my use of photo editing tools).

As the days have gone on, so have my tests and the expected-slow increasing darkness of my test lines 🥰

Correlation is not causation, and I am not saying my photo editing of my 5dp5dt AM test proves accuracy. But I am one positive case. And for some, that’s just enough to keep the hope alive a day or two longer 💜

5.0 out of 5 stars I don’t recommend driving yourself insane, but...
By K on June 29, 2021

I don’t recommend driving yourself insane (trying to read faint lines too early). But if you insist on it, here’s what I wish I’d found when I was driving myself crazy!:

In this study (https://pubmed.ncbi.nlm.nih.gov/16295647/), the FRERs detected levels as low as 6.3 mIU/mL. <5 mIU/mL is considered a negative blood test, just to clarify.

I did a natural (no meds) FET cycle with an hCG trigger (Ovidrel). I tested out the Ovidrel. Negative at 4dp5dt (4 days post 5 day transfer and 10 days post Ovidrel 250 mcg).

On day 5 after the transfer of a 5 day old non-expanded blast (5dp5dt or about 10dpo - that’s 10 days post ovulation), nothing appeared on the test with first morning urine between the recommended 3-10 min window read. HOWEVER, a few hours later (I know, I know) I thought I saw something. This is where I drove myself insane.

Can deposits from the urine settle on a test line after 10 minutes? Yeah, sure. I don’t really know, because I’m not a chemist nor expert in these tests. I’ve just taken hundreds of them 🤷‍♀️ I also still have all of my positive tests (and the negatives leading up to the days before the positive ones) from 10 years ago. None of them have changed (from negative to positive or the reverse, acquired a false line, nothing).

I dabble in photography as a side hobby and understand photo metadata (from learning PhotoShop) well enough to know that I am not manipulating negative tests to positive ones simply by editing pictures of my early tests. I am quite simply just using tools to visualize certain aspects of the existing data of the picture.

These test have a phenomenal ability at low-level reads! Albeit, visually difficult to the naked eye at these extremely low levels.

The best thing I can recommend (again, if you insist on making yourself crazy too early in the game) is to take a close look (and maybe even a picture-I did not) of the test BEFORE peeing on it. I did notice incredibly faint grayish test lines (but not on the control part) on my tests before I took them. And I struggled to visualize if my early faint positives were actually that gray line or pink (hence my use of photo editing tools).

As the days have gone on, so have my tests and the expected-slow increasing darkness of my test lines 🥰

Correlation is not causation, and I am not saying my photo editing of my 5dp5dt AM test proves accuracy. But I am one positive case. And for some, that’s just enough to keep the hope alive a day or two longer 💜

Reviewed in the United States 🇺🇸 on June 21, 2022

Reviewing mostly so I can show the other obsessive testers what our FRERs looked like at each beta. I know how much I valued that information from others a week ago. We got our first FRER positive at 4.5 days past 5 day frozen embryo transfer. It was incredibly faint, but definitely there. These tests have to be super sensitive because I’m confident (based on our 11.5 dpt beta) that our 4.5 dpt number had to be incredibly low. I always took a Wondfo cheap test at the same time and they *generally* showed the same trend but they were often erratic and scary. Some days they showed more progression than the FRER and other days they showed less. The FRER line steadily darkened while the Wondfo line was barely visible until day 9 or 10, then bounced around a bit. Thankful for FRER! Best of luck and baby dust to all of you!

5.0 out of 5 stars Accurate, reliable & early
By Ross Christensen on June 20, 2022

Reviewing mostly so I can show the other obsessive testers what our FRERs looked like at each beta. I know how much I valued that information from others a week ago. We got our first FRER positive at 4.5 days past 5 day frozen embryo transfer. It was incredibly faint, but definitely there. These tests have to be super sensitive because I’m confident (based on our 11.5 dpt beta) that our 4.5 dpt number had to be incredibly low. I always took a Wondfo cheap test at the same time and they *generally* showed the same trend but they were often erratic and scary. Some days they showed more progression than the FRER and other days they showed less. The FRER line steadily darkened while the Wondfo line was barely visible until day 9 or 10, then bounced around a bit. Thankful for FRER! Best of luck and baby dust to all of you!

Images in this review

How soon is too soon to get a positive pregnancy test?

How long does it take for hCG to show up in urine?