The subtle side eye, the raise of an eyebrow – both are gestures used to express emotions. However, perceiving these gestures can be amiss for some.
Scientists at University of Rostock, University Greifswald, and University of Postdam published a study in NeuroScience in 2019 that found that women who took oral contraceptives have a harder time interpreting emotional cues.
Scientists invited 95 participants aged 18 to 35 to take part in the study. The 95 participants included 42 women who took oral contraceptives and 43 who did not. Of the 42 women who took oral contraceptives, half the women were taking oral contraceptives with androgens and the other half were taking oral contraceptive without androgens. 
Androgen are steroids whose main purpose is to be converted to female hormones called estrogens; hormones influence behavior or mood, among other things. 
In order to gain more information on the participants, they were asked to complete a series of questionnaires regarding their menstrual cycle, contraceptive usage, age, education, distress, and empathy.  
Participants then completed the emotion recognition task using the RMET (reading the mind in the eyes test). This test assessed participants’ ability to recognize emotions based on subtle eye movements. Participants were then shown black and white pictures on a screen and had to provide a label that best described the expression by pressing a button corresponding to their answer as quickly as possible.
Based on a score comprised of correctness and response time, women who took oral contraceptives were less accurate in emotion recognition than women who did not take oral contraceptives. 
One interesting thing to consider, however, is that oral contraceptives typically suppress the amount of estrogen produced. 
Since the women who took oral contraceptives had lower estrogen levels, such lower levels may have been the reason why the women’s emotional recognition was impaired.
With all that being said, current studies on the topic are scarce, and overall more research is being conducted the emotional effects of oral contraceptives. More studies that offer more complex emotional recognition tests may help to identify emotion impairments in women’s recognition of emotion. 
The more we know about the emotional side-effects of oral contraceptives, the more informed decisions consumers can make.