A low prepregnancy weight and pregnancy weight gain cause low birth weight. The purpose of this study was to describe the correlation between the pre-pregnancy weight every trimester weight gain and body mass index pre-pregnancy with the birth weight and to determine the most influential factors that have a relation with the birth weight. This study used a retrospective cohort design with the number of samples is 153 expectant mothers, including the babies that took an antenatal care and the women who gave births health centers in Padang 2016. The data were collected through cohort register and birth date. Correlation analysis and multiple linear regression were used to determine the strength and direction of relationship independent variables and birth weight. Based on this study result, it was found that the average of birth weight is 3.135.23 grams (95% CI: 3.078.32 – 3.192.13). The maternal weight gained of expectant mother in the first trimester (p = 0.029) and second trimester (p = 0.005) had a significant correlation with the birth weight, while the pre pregnancy weight (p = 0.051), maternal weight gained in the third trimester (p = 0.893), and the pre pregnancy BMI (p = 0.107) had no significant correlation with the birth weight. Based on prediction model, it is
acquired that the birth weight = 2.605.38 + 7.35 prepregnancy weight + 0.035 second trimester weight gain. The most influential variable was the maternal weight gain in the second trimester.
Keywords: Pregnancy weight; birth weight; BMI