摘要:Introduction: Children are more risk-prone group of the population and low birth weight (LBW) is the leading cause of newborns' mortality and morbidity. LBW is defined as child's birth weight lower than 2500 g. Many maternal and fetal factors are determined as risk factors of LBW. This study tries to detect related factors to LBW and effect of them on children's growth pattern up to sixth month of life in Health centers of Urmia city, Iran. Materials and Methods: A cross-sectional study was carried out in Urmia city using registered data from mothers` documents. All related data such age and weight of infants, mothers' age, gestational age (GA) at the time of delivery, time gap between two pregnancies, past history of abortion, prenatal care history, systemic and underlying diseases, hemoglobin of mothers during pregnancy, and pattern of infant's growth up to sixth month of age were registered in a questionnaire. All registered data were transferred to SPSS 15 software and analyzed. Results : Mean ± SD of birth weight was 3071 ± 625.66 g. There was a significant relationship between birth weight and mother's age ( P P P P Conclusion: Our results show that LBW is related to multiple causes and that most of them are preventable with educational programs and also strict and regular prenatal care. Decreasing incidence of LBW children can be achieved by cooperation between different parts of health and clinical systems.