Hi!
Although I can not give an explanation, I read something on this subject
which might be of some help. So far, this discussion was about the so-called
secondary sex-ratio, which means the sex ratio at time of birth.
I have read an article in which the primary sex-ratio, i.e. at some time
during pregnancy, was analysed. The researchers found out that this sex
ratio was even higher. I think it was about 130 boys/100 girls. This
implicates that the proportion of male fetal losses is remarkably higher
than the proportion of female fetal losses.
Unfortunately, I can not remember the source of this article, I am afraid.
But it might be useful if you send your request to mailing-list related to
demography (I think there is no newsgroup on demographics so far?!?). If I
should forward your message to a demography mailing list, you may send me an
e-mail.
Roland
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