Background: Over the last two decades, nanotechnologies and the use of nanoparticles represent one of the greatest technological advances in many fields of human activity. Particles of titanium dioxide (TiO 2) are one of the nanomaterials most frequently found in everyday consumer products. But, due in particular to their extremely small size, TiO 2 nanoparticles (NPs) are prone to cross biological barriers and potentially lead to adverse health effects. The presence of TiO 2 NPs found in human placentae and in the infant meconium has indicated unequivocally the capacity for a materno-fetal transfer of this nanomaterial. Although chronic exposure to TiO 2 NPs during pregnancy is known to induce offspring cognitive deficits associated with neurotoxicity, the impact of a gestational exposure on a vital motor function such as respiration, whose functional emergence occurs during fetal development, remains unknown.Results: Using in vivo whole-body plethysmographic recordings from neonatal mice, we show that a chronic exposure to TiO 2 NPs during pregnancy alters the respiratory activity of offspring, characterized by an abnormally elevated rate of breathing. Correspondingly, using ex vivo electrophysiological recordings performed on isolated brainstemspinal cord preparations of newborn mice and medullary slice preparations containing specific nuclei controlling breathing frequency, we show that the spontaneously generated respiratory-related rhythm is significantly and abnormally accelerated in animals prenatally exposed to TiO 2 NPs. Moreover, such a chronic prenatal exposure was found to impair the capacity of respiratory neural circuitry to effectively adjust breathing rates in response to excitatory environmental stimuli such as an increase in ambient temperature.Conclusions: Our findings thus demonstrate that a maternal exposure to TiO 2 NPs during pregnancy affects the normal development and operation of the respiratory centers in progeny.< Réduire