The main purpose of our study has been to establish a link between the administration of intravenous fluids during Labor and the weight loss experienced by infants during hospitalization. We conducted a retrospective observational study using a descriptive and comparative method. We studied 150 records of patients who gave birth at term (low-risk pregnancy) of a single healthy new born with breastfeeding in a university hospital center between 1 January 2016 and 31 July 2016. Maternal, obstetrical and neonatal characteristics were registered to determine the influence of vascular filling by univariate and multivariate analysis and identified factors that may lead to increase neonatal weight loss. One hundred and fifty mother-child couples were studied. Newborns whom mothers received at least 1500 mL of solute during Labor lose significantly more weight until the third day of life ( < .001) compared to women who received less than 1500 mL, also observed for neonatal weight loss greater than 8% ( = .043). In addition, the obstetrical factors most significantly associated with an increase in the volume of solute injected were the duration of Labor ( < .001), the administration of oxytocin ( < .001), epidural analgesia ( = .01) and emergency cesarean section during Labor ( < .001). We found a link between vascular volume injected during Labor and increased risk of neonatal weight loss. Taking this factor into account when monitoring Labor in the birth room is essential to prevent and adapt neonatal management in the event of excessive weight loss. Influence of intrapartum maternal fluids on weight loss in breastfed newborns.