In response for a reference request back in Feb (I am behind), CDC with FDA
published an article showing that the more a mother breastfeeds her infant,
the fewer episodes of diarrhea and ear infections the infant has.  The
article can be found at http://www.pediatrics.org.  The reference is Scariati,
Grummer-Strawn, and Fein, " Longitudinal Analysis of Infant Morbidity and
the Extent of Breastfeeding in the United States."  Pediatrics Vol. 99, #6,
June 1997, p. e5.  (It is on the electronic pages; abstract only in the
hard copy journal.)