Women at their peak fertility find the scent of men with high testosterone levels more appealing, a new study has found.
Previous research has shown that ovulation can impact a woman's mating preferences. Studies have found that women in the fertile phase of their menstrual cycle favour more masculine traits, such as a deep voice or manly face, characteristics associated with the hormone testosterone.
In the new study, researchers tested whether women's sexual scent preferences changed depending on men's levels of testosterone and cortisol, LiveScience reported.
Research has also suggested fertile women are attracted to men with high levels of the stress hormone cortisol, which may be involved in stronger immune systems.
Male volunteers were given T-shirts to wear for two consecutive nights, during which time they were prohibited from using scented soaps or detergents; drinking or smoking; or eating garlic, onion and other pungent foods.
Then, female volunteers sniffed the men's shirts and rated the pleasantness and intensity of the smells on scales from 1 to 10.
The women also completed a questionnaire about their stage in their menstrual cycles and whether they were using hormonal contraception.
The researchers took saliva samples from the men to measure hormone levels of testosterone and cortisol.
Women who were at the most fertile stage of their menstrual cycles preferred the smell of men with higher testosterone, rating these "manly" shirts as the most pleasant.
However, the women showed no preference for the smells of men with higher cortisol levels.
Researchers also found that without taking the women's fertility into account, neither hormone had an influence on how attractive the men smelled.