Introduction: The nutritional status along with physical and mental development of infants is an effective factor on children’s health  throughout the life. Various strategies have, so far, been used to achieve optimal infant growth.  Using  non-professional support is one of these methods . This study aimed to investigate the effectiveness of peer support on the growth patterns of infants aged below one year old.
 
Materials & Methods: In this clinical trial, 240 primiparous women were randomly divided into two experimental and control groups. The control group received standard education and the experimental group was, besides receiving the same education,  supported by 30 breast feeding consultants (women with successful breastfeeding records) during the 6 months of  postpartum. The infants’ growth and developmental patterns were evaluated at the end of 1,2,4,6 and 12 months, respectively. This clinical trial was carried out in all the maternity hospitals and health centers of Ilam city (western Iran) during July 2010 to April 2012. Data were collected using a questionnaire and then analyzed using SPSS software version 16 and statistical tests including mean, percentage, Chi square test, Fisher test.
 
Findings: At 1, 2, 4.6 and 12 months of our reaerch, the two groups demonstrated a significant difference in terms of accommodation with the standard curve of weight gain, (P=0.001). The mean heights in both the groups was significantly different at 2, 12 months(P=0.001). The mean of head circumferences in the groups did not show any differences significantlym, (P>0.05).
 
Discusion & Conclusion: Our investigation came to the ocnclusion that besides encouraging mothers to continue lactation, peer support can be effective in promoting the growth and developmental patterns of children.