Oddly enough, I'm in the middle of editing a review article on the subject
right now. The writer is very well informed and cites about 40 references,
including four new studies published in the UK recently. I don't have it in
front of me now (it's Saturday morning!) and I can't recall the more
technical bits but she does mention that the bf-ing practices of previous
years may have contributed to the risk of bleeding incidents, namely:
delayed intiation of breastfeeding and regulated feeding thereafter. Why?
Because, colostrum, apparently, has relatively high levels of vit k, as
does hind milk. (This bit not referenced - I've got to chase her on that! -
but I've read this information elsewhere, too).

She also mentions that most vit k interventions raise levels to adult
levels and suggests there may be a reason, of which we're not yet aware, to
account for the newborn's relatively low levels. She generally refutes the
leukaemia business, but does cite one study suggesting a vague associations
with other cancers. She outlines various vit k policies from around Europe
and their outcome. I think she concludes that the subject remains pretty
inconclusive.

I understand that some sort of official Dept of Health publication is due
soon in the UK. I personally follow Jack Newman's line to the effect that
this is one occasion on which nature may have got it just a little bit
wrong - although, illogically perhaps, I refused vit k for my three babies.
Hannah
(midwife and National Childbirth Trust breastfeeding counsellor, UK)
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