Purpose: The purpose of this study was to examine the relationships between variety pregnancy related factors and postpartum BMI change. Methods: Analyzing the BMI of 125 postpartum women in oriental medical hospital of O O university from March, 2008 to May, 2008. Age, pregnancy period. type of delivery, parity, pregravida(PG) BMI, weight and BMI gain during pregnancy, gestational maximum(GMx) BMI were recorded. BMI also checked on each postpartum 7days(P7d), 14days(P14d), 90days(P90d), And we distinguished into Sasang Constitution by QSCC II. Results: The following results were obtained: 1. Age. pregnancy period were not correlated to postpartum BMI change. 2. PG BMI were lower in normal delivery group than caesarean delivery group. 3. PG BMI was lower in primipara group than multipara group. Weight and BMI gain during pregnancy. P90d BMI were lower in multipara group. 4. PG, GMx, P7d, P14d, P90d BMI were significally high in Taeumin. 5. PG BMI were correlated to GMx, P7d, P14d, P90d BMI. 6. Weight and BMI gain during pregnancy were correlated to GMx BMI and P7d, P14d, P90d BMI, BMI loss. Conclusion: This results suggested that weight and BMI gain during pregnancy have the best relationship with postpartum weight change.