Breastfeeding contributes to the health of the child and the mother. Given the lack of studies carried out in France, it is relevant to examine, besides the sociodemographic factors, the psychosocial and the relational factors. The objectives of this study are to describe the proportion of mothers who breastfeed up to six months and to identify the sociodemographic, psychosocial, and relational factors. This is a prospective, observational, single-center cohort study. The instruments used are the socio-demographic and clinical data questionnaire, the Maternal Sensitivity Scale, the Social Behavior Inventory and the Situational Anxiety Inventory. Of the 247 mothers who participed in the study, 134 (54.3 %) responded at six months and fifty-five (41.0%) mothers reported breastfeeding at six months. Multivariate analysis revealed the significant factors associated with the continuation of breastfeeding up to six months: the determination of mothers to breastfeed (OR (95 % CI): 3.99 (1.04 to 15.31)), high maternal sensitivity at 48h (OR (95 % CI): 0.16 (0.03 to 0.84)) and the presence of maternal anxiety at 48 h (OR (95 % CI): 1.18 (1.06 to 1.32)). An interactionist approach that takes into account maternal sensitivity is a promising avenue for supporting breastfeeding. Psychosocial and relational factors are fields that need to be explored. Knowledge of these factors can strengthen the strategies to inform and support breastfeeding mothers.