So I've seen a lot of other women say their once-regular periods suddenly became unpredictable after they began TTC. I've been having the same problem, and my doctor thinks we've found the reason. Up until we started trying in September, I had 28-day cycles, like clockwork. Since then they've varied from 35 to 46 days; basically each month my ovulation has been delayed by an unpredictable number of days. Bleeding has been somewhat abnormal, too. Always starts with spotting about 3 days before and then the blood is thicker and darker than normal, though not especially heavy.

Had some routine blood work done and turns out my tsh is a bit high (5.18). My doctor thinks I haven't been having sporadic periods, I've been having very early miscarriages. One after another. At least 3 in the last 5 months. Hypothyroidism seems to be a common cause, or at least strongly connected. We're getting a more comprehensive blood test done to see exactly what's going on with my thyroid, and I'll update this once my results are back.

The bright side is 1) this is easily treated and the synthetic hormone is safe for pregnancy (in fact, if I didn't take it and somehow didn't miscarry, the fetus would likely not develop properly), and 2) my husband and I are otherwise able to get pregnant and probably won't need fertility treatments, after all.