Men may be able to smell how fertile a woman is, research suggests.
Scientists from the University of Zurich asked a group of males to rank the body odours of 28 women of a reproductive age.
The women had previously been tested for their levels of key fertility hormones.
All the men agreed the most pleasant odours were given off by women with the highest levels of oestrogen.
Oestrogen regulates the menstrual cycle and causes eggs to mature in a girl’s ovaries when she reaches puberty.
Since this hormone is a ‘signifier of fertility’, the findings suggest ‘body odours are linked with reproductive health, which men can sense via smell’, the researchers said.
However, for around a quarter of couples who are struggling to conceive, there is no clear cause.
Past studies have shown the smells produced by a woman’s hormones can make her more attractive to the opposite sex.
However, whether this is an indicator of her fertility was unclear.
To find out more, the researchers asked men to rate the body odours of 28 healthy women.
The women had previously been tested for their levels of the hormones estradiol, progesterone, testosterone and cortisol.
Estradiol is one of four ‘dominant’ oestrogen hormones that occur naturally in women.
Progesterone maintains the lining of the uterus in preparation for the attachment of a fertilised egg.
If ovulation does not occur, progesterone levels fall and a woman sheds the lining during her period.
Although testosterone is higher in men, it also gives women their sex drive.
Finally, cortisol, ‘the stress hormone’, was looked at. Feeling frazzled is known to affect a woman’s chances of conceiving.
Results revealed all the men found the odours of women with high levels of estradiol in their saliva the most attractive.
Perhaps surprisingly, the males were also drawn to the females who produced low amounts of progesterone, despite its links to fertility.
The full results will be presented at the 50 Years of Psycho neuroendocrinology conference in Milan on Saturday.
‘Since estradiol and progesterone levels are signifiers of reproductive health and fertility, researchers suggest body odors are linked with women’s reproductive health, which men can sense via smell,’ the authors wrote.