There are a number of issues involved here.  It is good that the mothers
are getting morphine rather than meperidine (demerol, pethidine).
Meperidine and its active metabolite have very long half lives, though
even at that, I do not find that *practically*, the babies are affected
even if the mother does get meperdine postop. (It is different if the
mother gets the meperidine during labour.  Then the baby gets a great
wallop of it.  The anaesthetists are not so worried about giving it then
are they, yet the effects are so much greater?)

The reason there is little effect is that the amount that gets into the
milk is still very small.  Unfortunately, many people, including
physicians, do not understand breastfeeding and drugs.  They act as if
the baby will get what the mother gets and this is simply not true.  As
a rule of thumb, 1% of the total dose the mother gets is what the baby
gets.  This is usually nothing to worry about. In Dr. Hale's book, he
states that after 15 mg IV/IM, the peak breastmilk level of morphine was
only 0.5 mg/l.  Thus, we say that a baby on day 1 or 2 may get as little
as 30 to 60 ml of colostrum (see below about *getting* colostrum).  This
means that even at the *peak* concentration, which does not occur
throughout the day, the baby would get only .03 mg of morphine in the
milk (using 60 ml of colostrum in 24 hours).  How about some data,
anaesthetists to back up your claim that breastfeeding is dangerous to
the baby.  Huh?

In the immediate postpartum period, it is true that there is little (BUT
ENOUGH, *if the baby is latched on properly and thus gets what is
available*--but this is another story and a pet peeve) colostrum, and
thus the baby would be getting very little of any medication.  This is
partly counterbalanced by the fact that there are gaps between the
alveolar cells which allow more drug into the breastmilk.  These gaps
are closing up after birth so that after about 4 or 5 days they are not
important, though it may take two weeks for them to close up completely.

So, get the data from the anaesthetists that morphine renders breastmilk
more hazardous than formula (the risks of formula feeding are very well
documented).  Until then, mothers should be encouraged to breastfeed
while getting morphine.

Jack Newman, MD, FRCPC