Due to importance of breast feeding on physical and mental health of

    infants , it   is   necessary  to  recognize  the  influenting factors  on the time

    duration  of  breast  feeding .  The   present   investigation  is   designed  to

    determine   the   relationship  between  environmental  tobacco  smoking

    (E.T.S) and Breast feeding  duration  (B.F.D)  among women reffered to the

    health   centers   supervised   by   Shaheed   Beheshty  University  of Tehran

    in 1998.

         A cohort   study  was  performed  on 70 women which were in a smoky

    environment during their pregnancy ,  Breast  feeding ( exposure ), and 70

    women which were in a smoke  free   environment  ( Non  exposure ). Our

    exposure   and   non   exposure   groups   were   matched   for  their age .

    education , profession and  type of   delivery.   Sampling   was  based   on

    nonprobablistic method . Relative  risk  and  attributable  rate of  E.T.S and

    B.F.D  were calculated.

         The   B.F.D   parameter   were   obtained   as  3.91.3   in  the  group of

    exposuer and 4.81.3 for non exposure  group (P<0.001). In  the  exposure

    57% of  women had more than 4.5 month of exclusive breast feeding and

    in non exposure group this was 31% (P<0.001).

         Breast   feeding   duration  is  decreased  for women being in an smoky

    environment.