Introduction: Lob birth weight (LBW) is a condition of fetal growth failure characterized by birth weight of fewer than 2,500 grams. LBW is influenced by several factors, including socio-economic, perinatal nutrition, infectious diseases, maternal hemoglobin levels, and pregnant women's compliance with taking iron tablets. This study aimed to examine the association between each risk factor toward the incidence of LBW. Methods: This study with a case-control design used a retrospective approach. From a population of 450 mothers with 0-10 months old babies, 35 LBW incidences were found, and 35 normal-weight babies were selected randomly. Questionnaires were used to identify pregnant women's socio-economic status and compliance with consuming Fe supplements. At the same time, the data for Hb levels and identification of LBW incidences were taken from the MCH (maternal child health) handbook. Statistical analysis used SPSS 16 with Somers'd correlation test. Results: The results showed that the correlation between education (p<0.001), socio-economic (income) (p=0.002), Hb level (p<0.001), and the compliance of pregnant women taking Fe supplements (p<0.001) were correlated with the incidence of LBW. It is necessary to optimize the consumption of iron tablets through assistance during pregnancy. Conclusion: Based on the results of the study that has been conducted, it can be concluded that there is a correlation between socio-economic (education and income), Hb levels, and compliance of pregnant women taking Fe supplements with the incidence of LBW.