[Avodah] Fasting on Yom Kippur

[Meir Shinnar]

WRT some responses:
1) RDR suggests subgroup studies could be done.  i am not an
obstetrician, and this is not my area of expertise. However, I am not
aware of such studies.  Furthermore,  I don't think any institutional
review board would allow any such randomized study. Population reviews
could be done with subgroup analysis, the question is how much
accurate data is available.

The problem with historical analysis is that unless the specific
complication is temporally closey related to the fasting - such as
delivery within the next week, it may be very difficult to adequately
control historical data - as one is essentially looking at the
complication rate of the Jewish (or at least nominally observant
Jewish population) versus others - and this becomes confounded by all
the other differences besides fasting.  The studies I have seen focus
on increased delivery rate in the week post Yom Kippur.

Animal studies can be done, and some have been done - but the precise
relevance can always be debated.

2) RET says that some rabbanim argue that this problem is not
mentioned in the shut literature - and therefore can't be a halachic
issue.  As initially stated in areivim, current medical thinking (in
general - not specifically in this area) would place far greater
credence in the analysis of large sets of clinical experience, than in
the experience of any single practitioner - and the lack of the
realization that this was a problem does not reflect on the skill,
concern, or knowledge of the individual practitioners involved.
This would clearly apply here.
 Whether the level of risk  rises to halachically significant level
may be argued - but the argument from silence is, from a medical
perspective, not a serious one.

3) RDMI suggests that current medical practice, and especially
obstetricians, are risk averse - and their level of risk assessment
may not be halacha'.  As per my initial post, one of the halachic
issues that needs to be determined is precise determination of what
levels of risk are halachically acceptable.  However, being risk
averse is one way of saying that one is machmir on pikuach nefesh,
which has resonance in halachic terms.  Furthermore, to the extent
that halacha, in the case of pregnancy, has agreed that physicians may
detemine whether a particular case is risky - means that being machmir
on fasting also  requires changing classical halachic norms - as the
norm of the average pregnant woman fasting and the norm of listening
to physicians about the risk are in conflict...(you can't go back home
again)  - and the question is which norm one is more willing to
change..

Meir Shinnar