Perinatal women dominantly protect-rather than submissively cede-resources when interacting with threatening-looking others.

When competing for resources, people appear particularly sensitive to social cues of threat, tending to submissively cede resources to more (vs. less) threatening-looking others. This tendency appears especially pronounced among those that are physically weaker and thus more vulnerable to harm. One phase of adult life during which humans are particularly vulnerable is the perinatal period, the months leading up to and immediately after parturition (giving birth). Previous evidence and models of parental care and motivation suggest that individuals would be especially sensitive to threats during this phase. Accordingly, here we tested for the first time the preregistered prediction that perinatal (vs. non-perinatal) women would submissively cede more to threatening-looking others when competing over resources. Contrary to these predictions, results showed that women in this phase (n = 86, tested at ~29 weeks gestation and 1-month postpartum) were less sensitive to social threat than were non-perinatal women (n = 53), dominantly protecting rather than submissively ceding resources against threatening-looking male strangers. These findings suggest that pregnancy may affect social and economic decision-making by reducing (rather than increasing) submissiveness to threat, consistent with a 'maternal aggression' response documented in many non-human mammals.