BACKGROUND AND AIM: Mothers’ exposure to ambient air pollution, including black carbon (BC), during pregnancy has been associated with several adverse birth outcomes. Although the presence of ambient combustion-related particulates was recently shown in the placental tissue of pregnant women, proof of placental translocation to the fetal circulation in a real-life human context is still lacking. Here, we screened human umbilical cord blood for the presence of BC as part of the combustion-derived particulate matter. METHODS: Cord blood BC load was determined in the framework of the ENVIRONAGE (ENVIRonmental influence ON AGEing in early life) birth cohort study. We exploited the non-incandescence related white-light generation by carbonaceous particles following femtosecond pulsed illumination to screen whole cord blood samples from 60 newborns for the presence of BC particles in a biocompatible and label-free manner. RESULTS:BC is identified in all screened blood samples, with an average (SD) particle count of 0.48 x 10⁵ (0.29 x 10⁵), 1.02 x 10⁵ (0.76 x 10⁵) and 2.87 x 10⁵ (2.12 x 10⁵) particles per mL cord blood for low (n=20), intermediate (n=20) and high (n=20) exposed mother-newborn pairs, respectively. Furthermore, the cord blood BC load is positively associated with the mothers’ residential BC exposure during pregnancy (n=60; r=0.72; p0.0001). Moreover, the carbonaceous nature of these particulates was confirmed. CONCLUSIONS:Identification of BC particles in the fetal circulation shows that ambient particulates can be transported towards the fetus and represents a plausible explanation for the observed detrimental health effects from early life onwards. KEYWORDS: Air pollution, In utero exposure, maternal-fetal transfer, black carbon