Research published online April 23 in Psychological Science found that hormonal fluctuations associated with fertility influenced women’s religious and political orientation differently depending on their relationship status.

The study was based on the hypothesis that “reproductive goals might drive political and religious attitudes,” Kristina M. Durante of the University of Texas at San Antonio and her colleagues explained. The study was co-authored by Ashley Rae of the University of Texas and Vladas Griskevicius of the Carlson School of Management.

The two part study found that single women tended to become more socially liberal, less religious, and more likely to vote for Barack Obama during the ovulatory phase of the menstrual cycle. Women in committed relationships, however, tended to become more socially conservative, more religious, and more likely to vote for Obama’s opponent Mitt Romney.

The findings suggested hormonal changes have different effects on women who have different reproductive goals. Durante and her colleagues noted previous research had found attitudes about sex predicted both religiosity and social-political views.

“Experimental evidence also has indicated that the local mating ecology influences women’s religiosity, such that the presence of more desirable, single females leads women to become more religious,” they wrote in their study. “Because a glut of single females might pose a threat to a woman’s preexisting romantic relationship, women are believed to become more religious and to espouse the sanctity of commitment to protect their relationships. Taken together, these findings suggest that religiosity and political attitudes are somewhat flexible and that people adjust their orientations to serve their current reproductive goals.”

Durante and her colleagues suggested similar reproductive concerns could account for the difference found between single and married women in regards to voting.

For the first part of their study, Durante and her colleagues surveyed 275 aged 18–44 years regarding their menstrual cycle, demographic information, relationship status, and religiosity. They found single women reported significantly less religiosity as their fertility increased, while women in committed relationship reported the opposite.

The second part of the study closely replicated the first, but focused on political views and behaviors. Durante and her colleagues surveyed 502 women aged 18–42 years regarding their menstrual cycle, demographic information, relationship status, religious and political attitudes, voting preferences, and willingness to donate money to either Obama or Romney.

Single women were more likely to vote for Obama and were less socially conservative than women in committed relationships regardless of their stage in the menstrual cycle. But the average differences between single and women in committed relationships increased near the the ovulatory phase, when fertility was at its peak. The probability of conception appeared to exacerbate the average differences between the two groups.

“We believe that the key difference between these two groups is that married or engaged women are more invested in their relationship and therefore would have considerably more to lose if their relationship were endangered. Increased religiosity and conservatism at ovulation may serve to deter married women from cheating on their spouse,” Durante and her colleagues concluded, noting additional research was needed to confirm their hypothesis.