Purpose: Maternal exercise has shown beneficial effects on maternal/foetal health; however, the effects of maternal exercise on neurocognitive development in prenatally stressed offspring are unknown. The aim of the current study was to determine if maternal exercise during pregnancy prevents the effects of stress on spatial memory and learning as well as on the dendritic outgrowth of hippocampal neurons in prenatally stressed offspring. Methods: Ten pregnant mice were divided into three groups: control (C), restraint stress (RS) and restraint stress + voluntary wheel running (RS + VWR). Between gestational day 1 and 14 the dams from the RS + VWR group were subjected to the VWR protocol for 4 h per day. Moreover, from gestational day 14 until delivery the pregnant females from RS and RS + VWR group were subjected to three daily stress sessions. Between postnatal day 52 and 56, the male mice born of the three groups of dams were evaluated in the Morris Water Maze, and then, their neuronal morphology was analysed. Results: The stressed mice showed higher escape latencies and a significant reduction in both the number of entries to and in the time spent in the quadrant target of the maze, compared to controls, along with a reduction in the dendritic outgrowth of the hippocampal neurons. Moreover, stressed mice born from exercised mothers showed an improvement in spatial learning and memory, along with an increase in the dendritic length of dentate granule cells. Conclusions: Maternal exercise during pregnancy may be a beneficial factor to prevent the cognitive impairments and to ameliorate partially the impairments in the hippocampal dendritic outgrowth exhibited by prenatally stressed mice.