anders_CPH said:

SaraMom3 said: ...everyone should be on fertility and pregnancy...

This is where I part company with the consensus forming above. The counter-case has not been addressed. Somebody upthread described the situation that does not fit, and the thread moved on rather than engaging with it, which is the failure mode this board is supposed to avoid.

One concrete data point for the thread. For anyone reading later: the numbers in this thread are worth checking against a primary source before you act on them, including mine. Half the figures circulating in this community trace back to a secondary summary that dropped a qualifier.

Dr.RaviCardio said:

Somebody upthread described the situation that does not fit, and the thread moved on rather than engaging with it, which is the failure mode this…

There is a second half to this that has not been said yet. Start from the measurement rather than the conclusion. Almost every disagreement here turns out to be two people measuring different things and comparing the numbers anyway.

A narrower follow-up, since the general answer is now clear:

How would you tell the difference between that and the alternative explanation?

Reporting back.

For the archive: it took about six weeks rather than the two I expected, and the difference between those two numbers was the whole of my problem.