Effects of a walk in a residential natural vs. urban environment on objective and subjective stress indicators in mothers and their infants

Despite growing evidence that nature positively influences mood and stress, its effects on young children, especially infants, are not well-understood. To explore this, we conducted an intervention study with 72 mother-infant dyads. Mothers and their infants went on two walks, one in a natural and the other in an urban residential environment. We assessed effects of the walks on both subjective and physiological stress indicators, including maternal self-reported stress levels, salivary cortisol in mothers and infants, and cortisol levels in mothers’ breast milk.No significant interaction was found between time and environment on objective and subjective stress indicators. However, a decrease in cortisol concentrations in mothers and infants during walks in both environments was observed, suggesting that the walking itself may have decreased cortisol. Exploratory results showed that maternal salivary cortisol levels continued to decrease up to one hour following a walk in a natural environment, but not after urban walks, hinting at beneficial stress-relieving effects of natural compared to urban environments at a later timepoint. Self-reported assessments also revealed a reduction in maternal stress levels in both environments, accompanied by heightened feelings of pleasantness and calmness. Moreover, during the walk in nature, mothers experienced an increase in mood valence and wakefulness, while mood arousal decreased (though no significant interactions were found).These present findings indicate that walks in residential natural versus urban environments do not differ in how they affect objective and subjective indicators of stress in mothers and their infants. Additional exploratory analyses suggest that for mothers walking in nature may result in stress-relief, with these effects potentially manifesting after a delay. This study advances our knowledge of how environmental factors influence stress, which can guide urban design policies aimed at enhancing mental health for specific populations and age groups.