New mothers' taste in men changes after giving birth, according to research from the University of Stirling.
Psychologist Dr Kelly Cobey discovered women experience a short-term change in their taste in men during the weeks following giving birth, known as the post-partum period, with their preference shifting towards less masculine-looking men.
Dr Cobey, from Stirling's School of Natural Sciences said: "Previous research has already shown that natural hormonal variation subtly alters women's social perception and preferences.
"Our findings show that pregnancy and the post-partum period – stages of natural yet relatively extreme hormonal variation – are also linked to these altered preferences with women experiencing a reduction in their preference for masculine male faces.
"We know from previous studies that low levels of masculinity in men are associated with greater paternal qualities and better infant care. It may therefore be new mums are more attracted to men who show physical cues they could offer the best infant care, rather than those who are most physically attractive."
Dr Cobey and her colleagues Dr Tony Little and Dr Craig Roberts sampled more than 100 women, studying their evaluation of masculinity and femininity in men's and women's faces during pregnancy and in the six weeks after.
Whilst women moved away from masculine male faces, their preference for femininity in women's faces remained unchanged.
Dr Cobey added: "Interest in attractive men and sex are obviously impacted by social and physical factors in the post-partum period, but our research provides evidence that some of the variance in sexual desire at this time could be explained by changes in social perception.
"This may help to provide an explanation for changes in women's attraction to their partner, or general shifts in sexual desire, across reproductive life events like pregnancy."
The Behaviour and Evolution Research Group within Stirling's Division of Psychology is renowned for its research on the influences of facial attractiveness on human mate choice and the role of hormonal changes on social perception and preferences.
In the recent Research Excellence Framework (REF) 2014, Stirling's Psychology Division was ranked 3rd in Scotland, with 100% of research Impact being rated as world-leading.
The full findings of this study are published in the journal Biological Psychology.
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Kelly D. Cobey, Anthony C. Little, S. Craig Roberts, "Hormonal effects on women's facial masculinity preferences: The influence of pregnancy, post-partum, and hormonal contraceptive use," Biological Psychology, Volume 104, January 2015, Pages 35-40, ISSN 0301-0511, dx.doi.org/10.1016/j.biopsycho.2014.11.002.