Approximately 1% of caffeine ingested by the mother is excreted in breast
milk.  The effect that ingested caffeine has on the infant, however will
depend on the 1/2 life in the infant. The half life of caffeine in a
neonate is 4 days ( much longer in a premature infant). The adult rate of
caffeine clearance is reached at 7-9 months of age. You can see therefore
that there is some potential for accumulation and possibly problems in the
infants of big coffee drinkers.
Laureen Lawlor-Smith
BMBS IBCLC
South Australia