The goal of this clinical trial is to learn if the addition of sodium acetate in neonatal PN works to prevent and treat metabolic acidosis and associated comorbidities in preterm neonates. It will also teach about the optimal doses of sodium acetate in PN. The main questions it aims to answer are: Is the incidence of metabolic acidosis reduced in preterm neonates who received daily Sodium acetate in PN therapy (treatment) during the initial weeks of life compared with individuals who received sodium chloride in PN (standard)? Is the rate of neonatal comorbidities reduced in preterm neonates who received daily Sodium acetate in PN therapy (treatment) during the initial weeks of life compared with individuals who received sodium chloride in PN (standard)? What are the optimal neonatal dosing recommendations/guidelines of sodium acetate in daily PN, which are required to prevent/treat metabolic acidosis in the early life of preterm neonates? Researchers will compare Sodium acetate in PN therapy to sodium chloride in PN to see if Sodium acetate works to prevent and treat metabolic acidosis and associated comorbidities. Included Participants: All the neonates were admitted to the NICU of AKUH and received PN during 28 days of their lives. Participants will receive sodium acetate or sodium chloride Written informed consent was obtained by parents/legal representatives (according to local regulations) before the initiation of PN. Gestational age \< 33 weeks Included in the study before 72 hours of life