Background: Young maternal age is included into the high risk of pregnancy. It is related to the increasing risk of maternal complication during pregnancy and delivery, also the risk of low birth weight incidence. Low birth weight (LBW) is defined by all the newborns whose weight less than 2500 grams. LBW including the major factor in increased morbidity and mortality neonates. The prevalence of LBW in Yogyakarta is 12,1%. Factors that can affect LBW include maternal age, education, occupation, birth interval, parity, hemoglobin levels, maternal nutrition, prenatal care, nutrition intake and socio-economic level also the frequency of antenatal care visits. Objective: The aim of this study is to determine the relationship between young maternal age compared to reproductive age with the risk incidence of low birth weight in PKU Muhammadiyah Gamping Hospital period from January 2012 – October 2016.. Methods: It was an analytic observational research using cross sectional approach. Information regarding the data for research was obtained from medical records. Sample were collected based on inclusion criteria using purposive sampling. There were 90 numbers of samples which consisted of 45 young maternal age group and 45 reproductive age group. Data was analyzed by univariate analysis and bivariate with chi-square test. Result: The result showed that the prevalence of young maternal age (<20 years old) is 15 respondents. Meanwhile, the prevalence of reproductive maternal age (20 – 35 years old) is 5 respondents. There was a significant correlation between young maternal age compared to reproductive age with the risk incidene of low birth weight (OR = 4,000; 95% CI 1,309 – 12,227; p = 4,000). Conclusion: There was a significant correlation between young maternal age compared to reproductive age with the risk incidene of low birth weight.