Monday will mark 13 weeks. The time at which I lost the last pregnancy and the farthest I’ve ever gotten in a pregnancy. I’m a little nervous.
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I have been meaning for a long time to clear up a post from several months ago. My father, trying to be helpful and using some numbers I gave him from our RE (that Jason and I had a 75% chance of success with no intervention), incorrectly assessed our successive chances. Here is what he wrote:
"Suppose you decide to try 4 more times, in future (Hope you are willing to look that far ahead).
What's the probability of success in at least one of those 4 times?
Probability of first failure = 0.35
Probability of first and second tries failing = 0.35 x 0.35 = 0.1225
Probability of 3 failed attempts = 0.35 x 0.35 x 0.35 = 0.042875
Probability of 4 failed attempts = 0.35 x 0.35 x 0.35 x 0.35 = 0.01500625
The probability of at least one success in those 4 attempts = 1 - 0.01500625 = 0.985"
It seemed a little fishy at the time since, in all my book and blog reading, the statistics definitely did not parse out so optimistically. But I thought, what the hell do I know about probabilities? His math must be right.
Anyway, the human body does not bend to such a straightforward probability model. I was confirmed in my intuition by some materials that Misfits posted after returning from her fabulous trip to Chicago where she met experts who had written books specifically about RPL. One of the books came with the table below, which corrected my father’s assumption that each “event” is independent from the other. In undiagnosed RPL – that is not the case; from occurrence to occurrence, the probability of success does NOT stay the same.
I have also included a seriously shocking graph depicting the estimated survival of human conceptions by gestation. They say that human reproduction is incredibly inefficient, and this graph certainly presents it as such.
Though not quite so optimistic as my father’s calculation, I think the RPL landscape (if the losses are unexplained) still presents a hopeful picture. Happy Thanksgiving.