I used to have spotting for several days prior to AF, but that more or less went away when I got on the right dose of natural thyroid hormone. My LP was still 10 days (sometimes 9), but the spotting stopped except for maybe 1 day before AF. Still, I spotted for about 4 days starting about a week and a half ago when I got my BFP. I got the BFP on 10 dpo and started spotting that same day. The spotting stopped last Thursday and I haven't seen it since. Hope it stays away!
Everything I've heard indicates that several days of pre-AF spotting (as opposed to a normal 0 to maybe 1 day of spotting) is usually a bad sign for being able to sustain a pregnancy, and a potential indicator of low progesterone or perhaps thyroid problems. That's why I was so concerned about my cycles when I learned this.
(I personally ignored the "typical" thyroid hormone ranges and did a bunch of research on what was average/"normal" in the population vs. what they will tell you is "good enough," and found a like-minded doctor who was willing to prescribe me a dose that keeps me in those normal ranges. The other thing they don't like to tell you is that if you are on thyroid hormone, your TSH is likely to drop way down in any case, and becomes pretty much meaningless. What matters is the actual levels of T4 and T3 in your blood.)
I will try to keep this all-about-me off-topic rant short, but in my experience, doctors are often so hell-bent on "not giving you an excuse to be fat" that if you are overweight and concerned about your thyroid, they will do almost anything to pooh-pooh the possibility that something might be wrong. If your TSH is anywhere close to the outdated "normal" range (and forget getting them to order T3 or T4 testing), they lecture you to go on a diet and refuse to discuss it any further. In my case, I didn't lose any weight anyway when I got regulated, but I feel tons better, my cycles normalized, and my temps increased into a more reasonable range. That's what tells me I am on the right dose or close to it.
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