'I tell women that the general rule is the amount
of *anything* in the milk is about 10% of the maternal dose.  '

But it isn't true...and couldn't it  worry mothers unnecessarily, and
reassure incorrectly, too?  Some drugs just do not get into the breast milk
at all, and some get in, in tiny negligable amounts, and for some, 10 per
cent of the maternal dose might be way too much. Some drugs get into the
breast milk and it really doesn't matter because they do not get absorbed
by the baby's gut and just go straight through.

Heather Welford Neil
NCT bfc Newcastle upon Tyne