Assisted childbirth, due to high mortality, is ubiquitous; this feature likely played a critical role in shaping human sociality & may have been mediated by women’s ability to detect & respond to the hormonal status of other women

The role of oxytocin in social support during pregnancy. Citlally Contreras, Elizabeth Pillsworth. Human Behavior and Evolution Society 31st annual meeting. Boston 2019. http://tiny.cc/aa1w6y

Abstract: Childbirth poses an exceptionally high mortality risk for human females compared to non-human primates. Assisted childbirth is, therefore, a ubiquitous feature of human populations, with assistance most often provided by other women. We propose that this feature likely played a critical role in shaping human sociality and may have been mediated by women’s ability to detect and respond to the hormonal status of other women. To test this hypothesis, we designed a pilot study in which we measured oxytocin response in pregnant and non-pregnant women. Participants were nine pregnant women, six paired with a close female friend and three paired with a female stranger. Participants provided information about their reproductive histories, social networks, their relationships with their study partner, and their current pregnancy, and participated in a childbirth education class practicing birth positions and support. Oxytocin was measured in saliva, obtained from all participants at four times during the study. Results suggest that while both pregnant and non-pregnant women exhibited an increase in oxytocin levels, the greatest increase was observed among pregnant women participating with a close friend. These results will be discussed in conjunction with a survey study assessing the role of close female relationships on pregnancy, health, and experience.