They also found that men generally agree on who smells the most attractive.
In the Swiss study from the University of Bern, researchers found that the higher a woman's levels of oestradiol and the lower her levels of progesterone, the more attractive her body odour was rated, suggesting the fertility signal.
Researchers made sure they "collected all odours at peak fertility to control for menstrual cycle effects on body odour attractiveness". It's also when women smell their best.
"We found that men highly agreed on which odours they found attractive and which ones they liked less," the study authors wrote.
"From an evolutionary point of view female attractiveness is thought to provide cues to various desirable qualities that males may seek for in mates.
"Having high oestradiol levels is one of the desirable traits that men may seek in a woman, since oestradiol is positively related to a woman's reproductive potential.
"Even though all the odour samples in the present study came from currently fertile women, raters chose those odours to be most attractive that came from women who were most fertile at that moment."
The scientists said the relationship between sex hormones and women's body odour was not clear.
But one possibility is that sex hormones act indirectly on body odour via body temperature regulation.
Basically they think increased skin blood flow and sweating may lead to the excretion of certain odours.
And they think their findings prove humans are much like the animal kingdom when it comes to selecting and competing over mates.
"Our findings suggest that some women generally smell nicer than others and that the attractiveness of women's body odour is influenced by their (sex hormone) levels rather than by individual preferences of the rater," they said.
