Effect of SMOF lipid emulsion on physical growth and extrauterine growth retardation in very preterm infants: Insights from a multicenter retrospective cohort study

•The effects of soybean, medium-chain triacylglycerides, olive oil, and fish oil (SMOF) versus medium-chain triacylglycerides /long-chain triacylglycerides (MCT/LCT) on physical growth and extrauterine growth retardation in very preterm infants have not been reported.•Compared with MCT/LCT, SMOF can reduce the risk for parenteral nutrition-associated cholestasis and metabolic bone disease of prematurity.•SMOF was an independent risk factor for lower weight growth velocity in very preterm infants but had no effect on the incidence of extrauterine growth retardation. The aim of this study was to investigate the effects of soybean, medium-chain triacylglycerols (MCTs), olive oil, and fish oil (SMOF) on short-term clinical outcomes, physical growth, and extrauterine growth retardation (EUGR) in very preterm infants. This was a multicenter retrospective cohort study of very preterm infants hospitalized in neonatal intensive care units at five tertiary hospitals in China between January 2021 and December 2021. According to the type of fat emulsion used in parenteral nutrition (PN), eligible very preterm infants were divided into the MCTs/long-chain triacylglycerol (MCT/LCT) group and SMOF group. Change in weight z-score (weight Δz) between measurements at birth and at 36 wk of postmenstrual age or at discharge, the incidence of EUGR, and short-term clinical outcomes between the two groups were compared and analyzed. We enrolled 409 very preterm infants, including 205 in the MCT/LCT group and 204 in the SMOF group. Univariate analysis showed that infants in the SMOF group had significantly longer duration of invasive mechanical ventilation and PN, longer days to reach total enteral nutrition, and a higher proportion of maximum weight loss than those in MCT/LCT group (all P < 0.05). After adjusting for the confounding variables, multifactorial logistic regression analysis of short-term clinical outcomes showed that SMOF had protective effects on PN-associated cholestasis (odds ratio [OR], 0.470; 95% confidence interval [CI], 0.266–0.831) and metabolic bone disease of prematurity (OR, 0.263; 95% CI, 0.078–0.880). Additionally, SMOF was an independent risk factor for lower weight growth velocity (β = –0.733; 95% CI, –1.452 to –0.015) but had no effect on the incidence of EUGR (OR, 1.567; 95% CI, 0.912 to –2.693). Compared with MCT/LCT, SMOF can reduce the risk for PN-associated cholestasis and metabolic bone disease of prematurity in very preterm infants and has a n