Abstract Background Stress during rearing has negative effects on the maturation of information processing in rodent offspring, but similar evidence in humans is absent. Prepulse inhibition (PPI) of startle is a measure reflecting the integrity of information processing. PPI does not depend on active cooperation, making it a suitable measure for studying newborns and infants. This study investigated whether postnatal development of infant PPI is influenced by self-reported stress in the mother. Methods 49 healthy term-born infants were studied twice, four days after birth and again at four months. PPI was assessed by presentation of acoustic startle stimuli (95dB) either alone or preceded (SOA 120ms) by a prepulse (75dB). Mother's social stress levels were assessed with the modified Trier Inventory for the Assessment of Chronic Stress (TICS). Cortisol saliva samples were collected from mothers and their children. Results ANOVA revealed a different development of PPI in infants whose mothers reported enhanced stress levels due to social isolation and reduced social recognition. Cortisol levels were related to mothers’ self-report stress, but not to PPI development in infants. Conclusions Maternal stress experience has an impact on the maturation of human infants’ information processing in the first four months after birth.