ObjectiveTo investigate the influencing factors of umbilical cord blood collection volume in newborns with congenital heart disease (CHD), so as to provide a scientific basis for promoting the development of umbilical cord blood reinfusion technology. MethodsA retrospective study was conducted on CHD newborns who were delivered in the Department of Obstetrics, Guangdong Provincial People's Hospital and underwent umbilical cord blood collection from August 2024 to January 2026. Clinical data related to pregnant women, newborns, placentas and umbilical cords were collected. ResultsA total of 144 CHD newborns were enrolled, including 50 in the simple CHD group and 94 in the complex CHD group. The mean maternal age was (31.0±5.0) years. Among the CHD newborns, 96 (66.7%) were male and 48 (33.3%) were female. Umbilical cord blood collection volume was significantly positively correlated with maternal weight, placental weight, umbilical cord length, neonatal body length, neonatal head circumference and birth weight, among which neonatal head circumference (r=0.315, P<0.001) and birth weight (r=0.327, P<0.001) showed the strongest correlations. Multiple linear regression analysis revealed that after adjusting for neonatal birth weight, placental weight, umbilical cord length and maternal weight, only umbilical cord length was an independent influencing factor for umbilical cord blood collection volume (B=0.488, β=0.262, P=0.007). ConclusionThe volume of umbilical cord blood collected from CHD newborns is affected by multiple factors, among which umbilical cord length is the most dominant one.