Variation in facial masculinity and symmetry preferences across the menstrual cycle is moderated by relationship context.

In women, changes in preference during the menstrual cycle have been documented for attractiveness judgements of odour and various physical and behavioural male traits. Although many studies have demonstrated greater attraction to masculine traits, such as male faces, bodies, and voices, at high fertility, several recent studies present null results for these shifts in preferences. Moreover, evidence for stronger attraction to symmetric faces at high fertility is equivocal. Here we examined variation in preferences across the cycle for both facial masculinity and symmetry according to relationship context. Using both within-subject (Study 1) and between-subject (Study2) designs, we show that women prefer masculinity and symmetry in male faces at times when their fertility is likely to be highest (during the follicular phase of their cycle) when judging the faces for short-term relationship attractiveness. No effect of cycle was seen for long-term judgements. These results indicate that cyclic shifts in women are most apparent when judging for short-term relationships, which may explain the null results in studies where only general attractiveness was assessed. Cyclical preferences could influence women to select a partner who possesses traits that may enhance her offspring's quality at times when conception is most likely and/or serve to improve partner investment when investment is important.