Background : The low nutrition and nutrition status of pregnant mother during pregnancy can give bad effect on mother and baby. One of them is low born weight (BBLR), it is the weight of newborn baby that is under 2500 gram. Purpose : To learn if there was a relation between mother weight gain and weight of newborn baby on primipara and multipara group. Research Methods : This research was a quantitative research, with non experimental or observational research design and used cross sectional approach. Chi square and correlation analysis was the method used to analyze the relation between mother weight gain and newborn baby weight on primipara and multipara group. Result : Based on the correlation test result there was no relation between mother weight gain and weight of newborn baby on primipara group with p value result 0,824 and multipara group with p value result 0,826. Conclusion : There was no relation between mother weight gain and weight of newborn baby on primipara and multipara in PKU Muhammadiyah Gamping Hospital.