The current research aimed to evaluate effectiveness of cognitive behavioural treatment on enhancing mental health of pregnant women and their infants gaining weight. In a quasi-experimental study, participants were randomly assigned to the experimental (64 persons) or control (78 persons) groups . The experimental group received an 8 session of cognitive behavior intervention. For all of the participants, data related to level of their  anxiety, postpartum depression, self steem and stress were collected as the pre test and post test. Results of analysis of variance indicated that in the post test state, cognitive behavior intervention led to decreas score of anxiety, postpartum depression and stress but did not show any significant differences in particpant's self steem. Also no change in either group was found on the measure of infants birth weight.The findings of present study demonstrate the effectiveness of cognitive behavior intervention in the improvement of postpartum mood disorders. Also results suggested that special attention should be given to psychological intervention to prevention, detection, treatmentof postpartum depression..