Introduction: Congenital anomalies are structural or functional defects during intrauterine life. The relationship between low birth weight and predisposition to a congenital anomaly is not well known. Objective: To evaluate the association between low birth weight and the manifestation of congenital anomaly in neonates. Method: A cross-sectional study was performed. The study population were mothers who delivered neonates in a hospital in Asuncion, Paraguay, in 2018. Data collection cards were created with maternal and neonatal characteristics. The outcome variable was congenital malformations at birth. The exposure variable was low birth weight, defined as the clinical report of weight less than 2 500 grams in a neonate. Results: Out of 225 women, 26,7 % were found to have presented mother-to-neonatal transmission infections (60/165); 102 (45,3 %) were preterm and 79 (35,1 %) had congenital malformations. A positive association was evidenced between history of low birth weight and congenital malformations (PR= 2,32; CI 95 %: 1,68-3,20). Conclusions: There is a positive association between a history of low birth weight and congenital malformations.