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Thread: Importance of FMU?

  1. #1
    Jenny Guest

    Default Importance of FMU?

    Hi all,

    Just wanted to know how much difference does it make testing with FMU verses say urine in the arvo? I mean, how much does the concentration differ and then how much does this influence the result?

    If the HCG is present, wouldnt this just be picked up anyway?

    Thanks for your help.

  2. #2


    Hi Jenny

    At the beginning of pregnancy, hCG is only around in small amounts, so the more concentrated the urine the better. You can just have nothing to drink and not go to the loo for four-six hours in the afternoon and, for hCG, there will be no difference. It's just easier to be able to drink and use the loo, that is why the first urine is recommended. And you can always test right now and if you get a BFN wait a couple of days and then do a FMU.

    A lot of hormones follow a daily rhythm, so when you have your urine (or blood) tested can affect the reading - for example, testosterone (in both men and women) is more concentrated in the blood at 9am and lower in the afternoon. But hCG isn't circadian so you can test at any time, but the more concentrated the urine the better chance the test has of picking it up.

    As for how much the concentration differs, keep some pots in the loo. Look at the colour of your FMU compared to one later in the day - the FMU can easily be 3-4 times more concentrated, depending on how much you're drinking in the day.

  3. #3

    Join Date
    Sep 2006


    Hi Jenny,

    When you are testing really early, say 10dpo its best to use FMU as you will have hcg in your urine but it wont be as high as it would for at lets say 16dpo. I tested on 10dpo with FMU and I got the faintest of a second line.

    You can test in the arvo but a lot of things affect how much hcg can be detected, drinking etc. If I was to test now with arvo urine I would get a result cause hcg levels would be so high even tho I have drunk 2l of water

    I hope I helped in some way...

  4. #4


    As per what the girls said I used FMU at 11 dpo and got a -ve then did a arvo wee at 15 dpo and got a +ve...

  5. #5
    richdi40 Guest


    With my m/c in June last year at 5w 4d, I never got my first +'ive until 15DPO and that was faint with FMU, when I fell pg again in Sept last year, I again tested with FMU, but this time I was 10DPO and got a faint :bfp. Sadly, this pg'y also ended with a D&C on Oct 26 at 7w 4d.

    FMU is definately more concentrated and will show up little amounts of HCG, if u r testing early.


  6. #6
    Jenny Guest


    Thanks ladies. I will make sure I test with FMU for the most accurate results.

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