Jo:  Here are a few references you could give AWHONN:  Newcomb PA, Storer
BE, Longnecker MP, et al.  Lactation and a reduced risk of premenopausal
breast cancer.  N Engl J Med 1994;330:81-7.  Yoo KY,ajima K, Kuroishi T,
et al.  Independent protective effect of lactation against breast cancer:
a case-control study in Japan.  Am J Epidemiol 1992;135:726-33.  Layde
PM, Webster LA, Baughman AL, et al.  The independent associations of
parity, age at first full term pregnancy, and duration of breastfeeding
with the risk of breast cancer.  J Clin Epidemiol, 1989;42(10):963-73.
United Kingdom National Case-Control Study Group.  Breastfeeding and risk
of breast cancer in young women.  BMJ1993;307:17-20.  Yang CP, Weiss NS,
Band PR, et al.  History of lactation and breast cancer risk.  Am J
Epidemiol 1993;138:1050-6.  McTiernan A and Thomas DB.  Evidence for a
protective effect of lactation on risk of breast cancer in young women.
Am J Epidemiol 1986;124(3):353-8.  Ing R, Ho JHC, Petrakis NL.
Unilateral breast-feeding and breast cancer.  The Lancet July 16,
1977:124-7.  Hope this helps.  Alicia. [log in to unmask]