I am on my third cycle of Clomid. The first two cycles I had were 26 days in length. I expected my period six days ago, and it has not started yet. I took a home pregnancy test on day 14 after ovulation and it was negative. I also had a blood HCG test done on the same day and it, too, was negative. My cycles before I started on Clomid were irregular; I would have two cycles of 26 days in length and then one cycle of 45 days.
I am wondering if I could be pregnant anyway, even though the blood test was negative. The other scenario is that this could be my 45-day cycle, but I thought that taking the Clomid would prevent a cycle of that length. Any guess about what's going on?
I have to believe that the blood test was right. The key to successful Clomid use is to generate a good ovulation. Sometimes the dosage isn't strong enough to do this, resulting in a delayed period because of a faulty ovulation.
In my practice, I generally get a serum progesterone on day 21 or so to see if there's been an adequate ovulation. Ovulation results in a corpus luteum—that part of the ovary that makes progesterone in the second half of your cycle. If there's a good progesterone level at day 21, then the dose of Clomid is right. If the progesterone is too low, then the next cycle should use a stronger dose of Clomid. All of this should be under the direction of your doctor, of course.
Another factor to consider is that after numerous cycles, Clomid loses its potency at triggering ovulation, so there needs to be a "rest" for a while.