From Dee Keith IBCLC< LLL leader, mother of 10 Breastfeed children.
Re: spitting up , something I see from time to time is a mother particularly
at 3-4-5 day post partum, with so much milk it pores down baby's throat .
Baby does a lot of gulping and swallows a lot of air. Baby then upchecks and
mother is petrified.  Mother then concludes that its her milk and offers AFBM
and child keeps it down because it didn't eat it a quit the same rate. Maybe
it doesn't taste as nice either, so the feeding goes more slowly. Then mom
may or may not try the breastmilk in a bottle and swears the kid upchecked it
also. Maybe, maybe not, Watch this baby nurse. It may be nothing it maybe
something else entirely. My own children have done this when I've had a
really strong let-down.