Birth weight less 3,000 gram have more risk to cause heart and stroke disease, 13% higher than birth weight < 3,000 gram. This study described about the correlation between prepregnancy weight, first trimester weight gain, second trimester weight gain, third trimester weight gain with birth weight. This study aimed to predict birth weight and find out the factors that most influence on birth weight. This study used a retrospective cohort design. Samples were 233 pregnant women and infants who perform antenatal care and deliver in Citra Medika Hospital and midwife maternity from January 2010 to December 2011. The data were collected through patient medical record and birth data. Correlation analysis and multiple linear regression were used to determine the strength and the relationship direction between independent variables and birth weight. The results revealed the averages of birth weight in the hospital and maternity midwife are 3,337.8 ± 353.72 grams (95% CI: 3,292 – 3,383). Prepregnancy weight, maternal weight gain in first, second, and third semester have a moderate power relationship and positive pattern. The prediction model of birth weight = 1,764.133 + 0.023 (pre-pregnancy weight) + 0.131 (first semester weight gain) + 0.037 (second semester weight gain) + 0.037 (third semester weight gain). The most variable effect is a first semester weight gain.