The environment that a mother experiences during her own gestation can have long lasting physiological and behavioural implications for her offspring, mediated via maternal effects. Although these maternal effects act at the level of the individual they influence population and ecological dynamics, through offspring traits such as dispersal and reproduction. Glucocorticoids are transferred from mother to offspring in utero and can result in maternal effects that persist into adulthood, including both physiological and behavioural alterations linked to offspring success in different environments. We manipulated the maternal hormone environment during late gestation in mice and tested how a low-stress prenatal environment influenced offspring behaviour as adults both in a novel environment and in response to a stressor. We found that exploration was not influenced by maternal stress levels, except when mice were exposed to a stressor. Offspring from low-stress mothers exhibited less exploratory behaviour and more fearful behaviour in novel environments and after exposure to an acute stressor. These results demonstrate a hormonally-mediated maternal effect that persists into adulthood, with strongest effects when environments change. We discuss the implications for an individual’s ability to respond to environmental challenges, and the implications for population dynamics.