The original question was:

Is it true or false that sore nipples are caused by the "negative pressure"
>caused by the baby's mouth being on the nipple too long? OR if the baby is
>at the breast but not actively sucking or swallowing (ie, not doing
>anything), does his mouth create "negative pressure" (which in turn is
>believed to cause sore nipples)?

My understanding was that this was asked because mothers  were being told
that they should not keep babies on the breast for too long for this reason.

My understanding of Woolridge is that the negative pressure is what keeps
the nipple securely in baby's mouth and helps form  a seal.  There will be
cases where the negative pressure is higher and may cause soreness for
various reasons, but not in the  average baby with a normal suck.    I would
think the baby may suck more vigorously when the milk flow is low at the
beginning of the feed.  A baby who is staying on a long time and sleepy,
nibbling, not really drinking, but has a normal suck pattern, is not going
to cause sore nipples just from being on for a long time.  I think this is
what Jack was trying to say. Not that there is no negative pressure.  Just,
that negative pressure is not *THE* reason for sore nipples, and in saying
that, the original question was being answered.
And I don't think there really is disagreement here.  Just different
semantics, and different interpretations of the original question.
My 2 agurot.  (Israeli "cents", worth about a quarter of U.S. cents).

Yael Wyshogrod IBCLC
Rechovot, Israel

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