The non-canonical NF-κB signaling may be a central integrator of a placental clock that governs the length of human pregnancy. We sought to identify fetal signals that could activate this NF-κB pathway in the placenta， and in turn， contribute to the onset of labor. Proteomics analysis of exosomes purified from fetal cord arterial blood revealed a total of 328 proteins， among which 48 were more significantly abundant (p?