Research Question: What is the influence of maternal nutritional status during pregnancy on the birth weight? Objective: To assess the effect of maternal nutritional status during pregnancy on the birth weight of the baby among tea tribe women in Dibrugarh district. Study Design: Field-based cohort study. Setting: Five tea estates in Dibrugarh District, Assam. Period of Study: One year (April 1998 to April 1999). Participants: A cohort of non-pregnant currently married tea garden women of reproductive age group (15-44 years) from similar socio-economic background. Materials and Methods: Oral questionnaire for age, family structure, obstetric history, annual income, and period of gestation. Anthropometric measurements of weight and height were recorded using bathroom scales and the anthropometric rod. Measurements of weight were repeated during the first, second, and third trimesters of pregnancy. Birth weight of the baby was recorded at delivery, irrespective of the period of gestation and mode of delivery. Statistical Analysis: Correlation co-efficient, standard deviation, and regression analysis. Results and Conclusions: Of all, 88% mothers had pre-pregnant weight of <45 kg, and 61% babies had birth weight <2500 gm. Subjects with better pre-pregnant weight had corresponding favorable total weight gain, resulting in better birth weight of the babies. Pre-pregnant weight had direct positive linear relationship with the birth weight. There is a need to improve the nutritional status of the adolescent girl in order to build up her pre-pregnant weight for a favorable birth weight.