Trying to Get Pregnant

Luteal Phase Length ?

I tested this morning and got a BFN at 14 DPO, so I'm most likely out of the running for this cycle, but I have a question about FF and luteal phase length.

Since this is my first month charting, FF recommended that I wait until 18DPO to test, since it didn't know yet how long my luteal phase usually is. (Clearly, I couldn't hold out 18 days.) I know that the luteal phase stays pretty consistant for each individual woman, so I understand that FF doesn't know when my period is due. However, should that really make a difference in terms of testing?

If three women have luteal phases of 10 days, 14 days, and 18 days respectively, and they all get pregnant, wouldn't they all be equally likely to get a BFP on day 14? They would all have implantation around day 6-10, so I assume that the amount of hcg in their urine would be similar at 14DPO, wouldn't it? I'm guess I'm wondering if FF tells you to wait until 18DPO to avoid wasting money POAS or if there's another reason.

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Re: Luteal Phase Length ?

  • Believe it or not, a test taken by a pregnant woman at 14dpo still may turn up negative (though the odds are stacked against you). Sorry for the BFN! But look at it this way. If my LP is consistently 10 days long, for many cycles, and then one cycle I make it to 12dpo, that could be an indicator of pregnancy. Of course odd things happen all the time.
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  • imagesulfababy:
    Believe it or not, a test taken by a pregnant woman at 14dpo still may turn up negative (though the odds are stacked against you). Sorry for the BFN! But look at it this way. If my LP is consistently 10 days long, for many cycles, and then one cycle I make it to 12dpo, that could be an indicator of pregnancy. Of course odd things happen all the time.

    Thanks! I had a feeling it would be negative since I've had cramps for three days now and my BBT is going down, but my husband was pushing for me to take one. I like that he's excited, so I figured I'd do it. I think it will be easier once I have an idea of how long my luteal phase is, because I'll know what my "normal" looks like.

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  • imagegreeneyed_bride:

    If three women have luteal phases of 10 days, 14 days, and 18 days respectively, and they all get pregnant, wouldn't they all be equally likely to get a BFP on day 14? They would all have implantation around day 6-10, so I assume that the amount of hcg in their urine would be similar at 14DPO, wouldn't it?

    I was wondering this too - I guess if FF doesn't know how long your LP usually is it can't tell you if you're "late", but would that even matter if you're pregnant?  That always confused me.

  • imageshannondannon:
    imagegreeneyed_bride:

    If three women have luteal phases of 10 days, 14 days, and 18 days respectively, and they all get pregnant, wouldn't they all be equally likely to get a BFP on day 14? They would all have implantation around day 6-10, so I assume that the amount of hcg in their urine would be similar at 14DPO, wouldn't it?

    I was wondering this too - I guess if FF doesn't know how long your LP usually is it can't tell you if you're "late", but would that even matter if you're pregnant?  That always confused me.

    Exactly!! It just made me wonder if there was another reason that it said 18 days, but I guess maybe it's just because most tests can detect pregnancy with 99% accuracy at 18DPO.

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  • imagegreeneyed_bride:
    imageshannondannon:
    imagegreeneyed_bride:

    If three women have luteal phases of 10 days, 14 days, and 18 days respectively, and they all get pregnant, wouldn't they all be equally likely to get a BFP on day 14? They would all have implantation around day 6-10, so I assume that the amount of hcg in their urine would be similar at 14DPO, wouldn't it?

    I was wondering this too - I guess if FF doesn't know how long your LP usually is it can't tell you if you're "late", but would that even matter if you're pregnant?  That always confused me.

    Exactly!! It just made me wonder if there was another reason that it said 18 days, but I guess maybe it's just because most tests can detect pregnancy with 99% accuracy at 18DPO.

    That's probably it - since they're not sure how long your LP is, they probably want you to wait until a pregnancy test would really be accurate.  I don't think many people have 18 day luteal phases, right?

  • imageshannondannon:

    That's probably it - since they're not sure how long your LP is, they probably want you to wait until a pregnancy test would really be accurate.  I don't think many people have 18 day luteal phases, right?

    I don't think so. FF says a "normal" luteal phase lasts 10-16 days, so there probably aren't a ton of people with 18 day luteal phases.

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  • I am glad you asked this question. I am on 16DPO and tested negative at 14DPO. Still no signs of AF. I looked in FF's chart gallery and there are quite a few charts where they had a negative at 14DPO and a positive and 16 and up. At least that is what I am hoping for now. Good luck to you.

  • imagekgninja:

    I am glad you asked this question. I am on 16DPO and tested negative at 14DPO. Still no signs of AF. I looked in FF's chart gallery and there are quite a few charts where they had a negative at 14DPO and a positive and 16 and up. At least that is what I am hoping for now. Good luck to you.

    Good luck to you, too! I just looked at your chart, and I wonder if it's possible that you actually ovulated three days later than FF said. I'm brand new at this, so I really have no idea, but since the temp for 3DPO is actually on the cover line, maybe that was actually the day you ovulated? Either way, your chart looks very pretty!

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  • FF wants everyone to have patience Stick out tongue All kidding aside, FF always gives me a test date of the day after my longest LP. FF mentions in their tutorials and Q&A that they recommend waiting "both to preserve your emotional state and to save money by not testing too early."
    Dx: Unexplained Infertility

    TTC #1 
    IUI's #1 - #3 Clomid = BFN's, IUI #4 Follistim = BFP
    Grayson arrived via emergency c-section on 7/28/12!

    TTC #2 
    IUI's #1 - #4 Follistim = BFN's
    IVF #1 w/ ICSI + PGS: Lupron/Follistim/Menopur
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  • I think others (and you) are correct that FF is being very conservative and wants you to wait until the percentages of positive would be higher. Good luck to you!

    image

  • Thanks, ladies!

    imagemdiblasi10:
    FF wants everyone to have patience Stick out tongue All kidding aside, FF always gives me a test date of the day after my longest LP. FF mentions in their tutorials and Q&A that they recommend waiting "both to preserve your emotional state and to save money by not testing too early."

    Ha! For some reason the phrase "to preserve your emotional state" strikes me as funny.

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  • imagegreeneyed_bride:
    imagekgninja:

    I am glad you asked this question. I am on 16DPO and tested negative at 14DPO. Still no signs of AF. I looked in FF's chart gallery and there are quite a few charts where they had a negative at 14DPO and a positive and 16 and up. At least that is what I am hoping for now. Good luck to you.

    Good luck to you, too! I just looked at your chart, and I wonder if it's possible that you actually ovulated three days later than FF said. I'm brand new at this, so I really have no idea, but since the temp for 3DPO is actually on the cover line, maybe that was actually the day you ovulated? Either way, your chart looks very pretty!

    Thanks. I was actually wondering about this as well. This is my first month charting so I can't really compare it to any other charts, which is driving me nuts ha ha.

  • I agree with PPs - if you've been charting for 2 cycles or less, they'll set your test date far later (for me, they set it at 19 dpo, as this is only my 2nd cycle charting).  After you've charted a few more cycles, FF is more confident in predicting your LP length and setting a test date for sooner than 19 dpo. 

    There are quite a few instances out there of women who didn't get a BFP until 17+dpo...even 20+ dpo!!  I'm hoping that's the case with me.  I'm at 17 dpo and got a BFN this morning.  I'm about to lose my mind. 

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