A new study published in the British Journal of Psychology provides evidence that women in the late stages of pregnancy and early motherhood do not display increased submissiveness when facing potential social threats. Contrary to the expectation that physical vulnerability would lead to conflict avoidance, the findings suggest that women in the perinatal period tend to aggressively protect resources when interacting with threatening-looking men.
The rationale behind this investigation is rooted in the evolutionary history of human development. Human infants are born in a state of high dependency, requiring significant time and energy from caregivers to survive. Throughout history, high rates of infant mortality likely necessitated specific cognitive adaptations in parents to help them assess and manage dangers in the environment.
Psychological theories, such as protection motivation theory, propose that people constantly weigh potential threats against their ability to cope with them. When the perceived threat outweighs the ability to cope, individuals typically adopt protective or avoidant behaviors.
This calculation is particularly relevant during pregnancy. The perinatal period, defined as the months leading up to and immediately following childbirth, is physically demanding. Pregnant women experience reduced physical mobility and significant metabolic costs associated with fetal development.
Because of these physical limitations and the high value of the developing fetus, previous models of parental motivation suggested that pregnant women should be highly risk-averse. The logic follows that if a pregnant woman is physically vulnerable, she should avoid escalation and confrontation to prevent harm to herself and her unborn child.
Past research supports the idea that pregnancy heightens sensitivity to danger. For example, pregnant women often show stronger reactions to disgust and are better at recognizing angry or fearful faces than non-pregnant women. The authors of the current study wanted to determine if this heightened sensitivity translates into behavioral submissiveness.
“While previous work demonstrated that pregnancy may change how women perceive threats—such as how fast they spot an angry or fearful face—we didn’t know how this might lead to changes in their actual behavior. Particularly, we became interested in knowing if this enhanced sensitivity to threat may impact their willingness to compete over resources they may need,” said co-author Shawn Geniole, an associate professor at the University of the Fraser Valley.
“On one hand, pregnancy brings new financial and other demands, making it important to compete for and secure resources (e.g., preferred/overtime shifts at work or better products/services). On the other hand, if pregnancy boosts sensitivity to social threats, it may bring greater cautiousness, increasing the likelihood of ‘backing down’ to avoid any risks of conflict or retaliation.”
“We therefore wanted to conduct this study to determine precisely how pregnancy, and more specifically the perinatal period—the months leading up to and immediately after delivery—would impact these types of competitive decisions. To do so, we used an experimental economics task in which women had to decide how to share resources with others.”
The researchers recruited a total of 139 participants. The sample included 86 perinatal women and a control group of 53 non-perinatal women. The perinatal group was tested at two specific time points: approximately 29 weeks into their gestation and again one month after giving birth. The control group also completed testing at two time points separated by a two-month interval to match the timeline of the pregnant participants.
The primary measure used in the study was the “Threat Premium Task.” This is a competitively framed variation of the Ultimatum Game, a standard tool in economic psychology. In this task, participants were given a set amount of virtual money, specifically ten coins, and asked to propose a split with a series of partners. The participants were told that the goal was to keep as much money as possible. However, there was a catch. If the partner accepted the offer, the money was split as proposed. If the partner rejected the offer, neither party received anything.
This design forced participants to make a strategic calculation. Offering a low amount was profitable but risky, as a threatening partner might be perceived as more likely to reject the offer out of spite or aggression. Offering a high amount was safer but resulted in less resource acquisition for the participant. This “threat premium”—the extra money paid to scary-looking partners—is a measure of submissive behavior.
“The women in the study had to carefully balance both the desire to maximize earnings and to avoid retaliation. We were particularly interested in how sensitive they would be—or how much their decisions would change—when interacting with others who appeared more or less threatening.”
The “partners” in this game were not real people but photographs of male faces. Unbeknownst to the participants, these faces had been digitally manipulated to appear either more or less threatening.
The results contradicted the preregistered predictions of the research team. The non-pregnant control group behaved as expected. They were sensitive to the social cues of threat and tended to offer more money to the threatening-looking men than to the non-threatening men. This indicates a typical strategy of appeasement to avoid conflict.
But the perinatal women showed a completely different behavioral pattern. Instead of paying a higher premium to threatening men, they became less generous. The study found that pregnant women were less sensitive to the social threat cues and less willing to cede resources. They dominantly protected their coins rather than submissively handing them over.
This effect was particularly pronounced during the pre-birth session when the women were in the third trimester of pregnancy. The data indicated that the anticipated “threat premium” was effectively eliminated in the perinatal group.
“The biggest takeaway is that pregnancy doesn’t necessarily make women more submissive,” explained co-author Valentina Proietti, an assistant professor at the University of the Fraser Valley. “Based on previous research, we originally expected that pregnant and postpartum women might be more prone to submissive behavior and more likely to relinquish their resources when faced with threatening individuals.”
“However, we found the exact opposite to be true: women in the perinatal period actually defended their resources more dominantly than those who weren’t pregnant, especially when they were dealing with people who looked more threatening. In short: while the common assumption is that heightened threat-sensitivity leads to caution in the face of such threat, our findings suggest it may actually trigger a more dominant drive to secure and protect the resources necessary for themselves and their growing families.”
These findings align with a phenomenon observed in non-human mammals known as maternal aggression. In many species, including rodents and bears, females become significantly more aggressive and protective during pregnancy and lactation. This biological shift prioritizes the security and provision of offspring over the mother’s own safety or tendency toward conflict avoidance.
The researchers suggest that in humans, this maternal defense mechanism may manifest as a refusal to be intimidated by social threats when resources are at stake. The drive to secure necessary assets for the growing family appears to suppress the usual tendency to back down from threatening individuals.
“This pattern may fit with what researchers call ‘maternal aggression’ in other mammals — think of a protective and potentially aggressive mother bear with her cubs,” the researchers told PsyPost. “While we didn’t measure aggression directly, the fact that perinatal women were less submissive in the face of potential threats aligns with this idea.”
“While our study used a more controlled economic task, the results may point toward a more general change in behavior during a truly unique life stage. Readers should think of the perinatal phase as a special/sensitive period—a time when a woman’s social and economic priorities may shift to meet the new demands of motherhood.”
“Although we used a rather simple economic task in our study, the same mechanisms at play here may extend to other types of competitive interactions in the real world, such as bargaining for better work or overtime shifts, navigating online marketplaces, or negotiating for services. We view this study as a first step in understanding how this special biological period reshapes economic decision-making, and we hope to explore these more ‘real-world’ economic interactions in future research.”
The study offers new insights into the psychology of pregnancy, but — as with all research — there are limitations to consider. The study utilized only male faces as the source of social threat.
“Although we’d ideally like to study real‑world economic interactions and other forms of competition that involve a variety of interaction partners, our study focused only on how women responded to threatening situations involving unfamiliar men. As a result, we still don’t know how perinatal women might behave in similar competitive situations with other women. That remains an important direction for future research.”
Additionally, while the sample size was relatively large for this type of research, distinguishing the specific effects of pregnancy from the general effects of parenthood requires even larger groups that compare pregnant women exclusively to women who have never had children.
The study also raises questions about the biological mechanisms driving this behavior. The researchers speculate that hormonal changes may play a key role. Testosterone levels, for instance, are known to rise during pregnancy. In men, higher testosterone is associated with the same type of dominant behavior observed in the perinatal women in this study.
However, the researchers did not measure hormone levels, so this link remains a hypothesis for future investigation. Future work might also explore how this resource-protection drive interacts with the known decreases in mating motivation that occur during pregnancy.
Looking ahead, “we would like to investigate how these effects may extend to real-world economic interactions and how changes in hormones during pregnancy may play a role and/or explain some of the findings here,” Geniole said.
“One ongoing challenge with this kind of research is finding a large enough sample of participants at the right moment in pregnancy or postpartum,” Proietti added. “If you are a professional who supports women during this period—whether you are a midwife, doula, lactation consultant, or work in a maternity ward—and you’d like to see this population be better represented in research, we’d be happy to connect by email at lifespan.lab@ufv.ca or through Instagram (https://www.instagram.com/bicocca_child_and_baby_lab?igsh=dGUxNmdpeDR4djEx) and share information about any future studies! If interested, reader can also check out some additional work at https://bicoccababylab.wixsite.com/website/en.”
The study, “Perinatal women dominantly protect—rather than submissively cede—resources when interacting with threatening-looking others,” was authored by Valentina Proietti, Ilenia Mastroianni, Valentina Silvestri, Martina Arioli, Viola Macchi Cassia, and Shawn N. Geniole.
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