Fiona,
Philip Zeskind, PhD, has done some interesting work on autonomic arousal
rhythms, neurological deficits, infant feeding.  He found that some kids with
very mild (undetectable to standard assessments) neurological dysfunction were
more vulnerable to SIDS if they were artificially fed.  His research is very,
very interesting.  These are a few of the references he gave at the ILCA conf
in Atlanta (1994).  He was just about to publish more, including something on
SIDS risk, so you might like to target a search on his name for more recent
references.

Zeskind, PS, Marshall, TR, Goff, D:  Rhythmic organization of heart rate in
breast-fed and bottle-fed newborn infants.  Early Development and Parenting
1(2):79-87, 1992

Zeskind, PS, Field TM:  Neonatal cry threshold and heart rate variability. In
Libsitt LP, Field TM, eds.: Infant Behavior and Development: Perinatal Risk
and Newborn Behavior.  Norwood, NJ, Ablex. (special edition of Infant Behavior
and Development)

Catherine Watson Genna, IBCLC  NYC  [log in to unmask]