Researchers collected urine samples from 33 women over 15 days to measure any fluctuations in estradiol, progesterone and testosterone. During the study, the participants were also asked to complete nightly surveys with their partner detailing their relationship satisfaction and perceptions of each other. None of the women were taking hormonal contraception and had each been in a relationship for 4 months or more.
“Women’s hormone levels change across their ovulatory cycles, and these changes are likely to affect their psychology and, perhaps, the way they feel toward their romantic partner. We found that the hormone that peaks just prior to ovulation, estradiol, was associated with more negative partner evaluation,” study author Francesca Righetti, an associate professor at VU Amsterdam told PsyPost.
This reduced relationship satisfaction in women was also found to impact the men. “Men also perceived their partner to be less satisfied when estradiol was high and, consequently, they experienced lower well-being,” Righetti said.
Still, the jury’s out on exactly why this is.
“Evolutionary theories have suggested that, when women are ovulating, they may be especially tuned into other men (e.g., men with good genetic qualities), and that’s why they distance themselves from their primary long-term partner. Our data weren’t totally consistent with this perspective, though, since estradiol was not associated with the degree to which women reported flirting and giving more attention to other men,” Righetti continued.
“But this may be due to the fact that, given our small sample, our female participants may not have encountered many attractive men during the duration of the studies. On the contrary, it may be that evolution has shaped women to pre-emptively disengage from their partner close to ovulation to be open and attentive to identify alternative partners that may be especially good reproductive partners.”