The modulation of social behavior and empathy via oral contraceptives and female sex hormones.

Oral contraceptives (OC) and endogenous female sex hormones in naturally cycling women (NC) are related to a wide range of psychological variables (eg, cognition and affect). Little research on social behavior has been done. One study documented a tendency towards more prosocial behavior in NC than OC women, but the underlying neuroendocrine mechanisms remain unknown. The sex hormones progesterone and estradiol are potential candidates. We analyzed social decision-making and social behavior in 83 healthy women (38 OC and 45 NC) via the Social Value Orientation (SVO) and in real social interactions within a paradigm adapted from behavioral economics. We also measured empathy, and collected saliva samples to quantify the basal levels of estradiol and progesterone. Our analyses revealed higher levels of prosocial behavior and emotional empathy in NC than in OC women, a finding supported by higher levels of prosocial decisions in NC than OC women in the SVO. Regarding the underlying biological mechanisms, we detected lower progesterone levels in OC than NC women. Exploratory analyses revealed a negative correlation between progesterone and trust on the trend level. We found no correlations between estradiol and behavior. Our findings provide evidence that OC modulate social behavior and initial indications of a possible modulation by progesterone. Further research is needed to replicate our findings and extend them to other social behaviors.