I understand that this post is old, but have you considered the potential differences in HCG benchmarks between the new FRERs with darker caps and the old clear cap ones?
It is important to note that late implantation in IVF, as indicated by lower hCG levels initially, does not appear to be associated with a higher risk of pregnancy loss. Factors such as embryo quality, uterine receptivity, and the pattern of hCG level increase seem to play a more significant role in determining the success of the pregnancy. This is in contrast to natural conception, where late implantation has been linked to a higher rate of miscarriage.
I purchased inexpensive tests from Amazon and I intend to test on the day of transfer. I find that testing regularly helps me feel more proactive during the wait and keeps me relaxed. I believe it is a personal choice and prefer not to stress myself out by not testing. The tests are affordable when bought in bundles, so why not? Despite my husband and mom thinking I am going overboard with it.
Can the Original Poster please provide a citation for the paper?
UPDATE: I found it here
Thank you for this incredibly helpful read.
Awesome post. Based on what I read, if I received a negative test 3 hours before reaching 5.5 days past a 5-day embryo transfer, does that mean I have a 25% chance of it being positive on day 6?
What is the distinction between First Response Rapid Result and Early Result?
I am in disagreement with another user. In my experience within the IVF community on Instagram, the chances of a positive result at 5 days post-5-day transfer are significantly lower. It is important to keep hope and not lose faith if there is no positive result after day 6, as most people do not see positives until day 7 or later.
I am currently 6 days past a 5-day embryo transfer and this morning I took a First Response pregnancy test on my second urine sample of the day. I only drank a small amount of water to take my medications. I saw a very faint line. Do you think implantation occurred on day 3 or 4 post transfer? Should the line be darker by 6 days post transfer?
This is the first test we took, using a cheap Amazon brand with a minimum of 25 miu hcg for detection, 8 days after the FET transfer. The line turned dark very quickly – is this a positive sign, even though it wasn’t a first response test?
Thank you for providing this.
Hello - I received a negative result with my first morning urine on 6 days past a 6-day embryo transfer. Does this mean I am not pregnant?
This is amazing - I appreciate it!!
Thank you for providing this information. Can you please explain what a faint positive result on 6 days past a 5-day embryo transfer means?
Hello OP. I have been following your post from a couple of years ago and found it to be very helpful and accurate based on personal experience. I recently had a day 6 embryo implanted and I was wondering if this means I should count back 1 day. For instance, would testing at 5 days post 5-day transfer be the same as testing at 4 days post 6-day transfer? Would it affect the accuracy of the test, which is said to be 76% accurate? Or does the timing not matter once the embryo has been implanted? Thank you so much.
Does this information also pertain to a 6-day embryo transfer? I have moved past day 5 and am now on day 6 and day 7, so I am wondering if there are any differences in the process at this stage.
Thank you for your informative post, it was extremely helpful! 
Your explanation was helpful and clear, thank you!
I had my transfer on Wednesday, 6/17 at 2pm. Would you consider the test I took at 6am this morning to be 4 days past a 5-day transfer (4dp5dt) or 5 days past a 5-day transfer (5dp5dt)?
Unfortunately, I received a clear negative result on the FRER test this morning.
I didn’t hold my pee for four hours. I had just gone to the bathroom 15 minutes before and my urine was clear. The test was spontaneous and not planned. It was a line test, not a digital one. I have been drinking fluids all day, so I will test in the morning.
Additionally, it was not a First Response Early Result (FRER) test.