The two week wait to find out if you’re pregnant can feel interminable. You want to test early but you’re afraid of getting disappointed by a false negative if you choose a test which is not very sensitive.
So which test is going to give you the most reliable result?
First Response Early Results (FRER) – the gold standard
If you spend time in fertility groups or forums, you will see the acronym FRER a lot.
The First Response Early Results test can detect very low levels of HCG. One study found it detected levels of 5.5 mIU/mL and another found it detected 6.3 mIU/mL.
HCG is what every pregnancy test measures. It starts to rise when the embryo implants, which usually occurs 6-12 days after fertilization.
If you do a blood test to measure your beta HCG levels (a beta test), a level of below 5 is considered not pregnant because some people naturally have a little HCG outside pregnancy.
The First Response Early Result (FRER) test can therefore detect the minimum amount required to qualify as pregnant.
Here is an example where the person had a beta HCG test of 5 mIU/mL the same day.
Here is another for 7 mIU/mL.
How about other tests?
Other red dye tests can also detect low levels but sometimes they are a little harder to read. The early lines might look like a hint of a shadow as the lines tend to be a bit wider. It can also be harder to see if they contain dye.
Here someone had a blood test that showed a level of 7.1 mIU/mL and compared several tests. The FRER test was removed from its plastic casing and doesn’t look the same as it would behind the little window but it serves as a comparison.
So you definitely choose to buy cheap test strips online rather than invest in FRER if you are a chronic tester. The advantage of using FRER is the confirmed sensitivity and the clearer faint lines.
You should also be careful to test with concentrated urine. This is one reason most people prefer to test with the first pee in the morning. When it is early, the levels are low and can easily be diluted by drinking before testing. Good luck!
References:
Cole LA, Sutton-Riley JM, Khanlian SA, Borkovskaya M, Rayburn BB, Rayburn WF. Sensitivity of over-the-counter pregnancy tests: comparison of utility and marketing messages. J Am Pharm Assoc (2003). 2005 Sep-Oct;45(5):608-15. doi: 10.1331/1544345055001391. PMID: 16295647. https://pubmed.ncbi.nlm.nih.gov/16295647/
Cole LA. The utility of six over-the-counter (home) pregnancy tests. Clin Chem Lab Med. 2011 Aug;49(8):1317-22. doi: 10.1515/CCLM.2011.211. PMID: 21812725. https://pubmed.ncbi.nlm.nih.gov/21812725/