Maternal weight gain during pregnancy is one parameter that can be used to assess the nutritional status of pregnant women. Both under-and over-weight gain can cause serious problems for babies. This study with cross sectional design aims to determine the relationship between increased maternal weight during pregnancy and infant birth weight. The sample was 107 postpartum mothers in January-April 2017 who were selected by purposive sampling. The results showed that of the 54 respondents who experienced an increase in normal body weight, most of them gave birth with normal birth weight as many as 51 respondents (94.4%), of the 41 respondents who experienced an increase in underweight most of them gave birth to babies with normal birth weight as many as 36 respondents (87.8), and of the 12 respondents who experienced an increase in excess body weight, most of them gave birth to babies with normal birth weight as many as 9 respondents (75%), so the value  = 0.005, r = 0.268 was obtained. In conclusion, there is a significant relationship between maternal weight gain during pregnancy and infant birth weight with a weak correlation