Objective: To determine if aged primigravid is a risk factor for newborn with low birth weight. Method: An analytical, retrospective, transversal observational, case and control study was conducted, with the clinical records of newborns, children of primigravid, attended at the Regional Hospital of Trujillo in the period 2010-2015. Of these we selected those who had a diagnosis of newborns with low birth weight or not, also meet with inclusion and exclusion criteria. A total of 72 cases and a total of 144 controls were obtained. Results: It was evidenced 9.72% of aged primigravid within cases. The aged primigravid is a risk factor for newborn with low birth weight, evidenced by an odds ratio of 5.062 with CI 95% (1.268-20.201), with a p <0.05. Conclusions: The aged primigravid is a risk factor for newborn with low birth weight.