Men buy all kinds of designer fragrances to try to attract members of the opposite sex, but new findings show the only scent they need is the one their bodies naturally produce.

According to a new study, women in their most heightened stage of fertility prefer the smell of a man's testosterone and even consider it attractive.

Researchers collected saliva samples from men participating in the study to test for both testosterone and cortisol hormone levels. Cortisol is a steroid hormone produced by the body's adrenal gland that can be manipulated by stress.

The men received white t-shirts to wear for two nights and were asked not to apply deodorant, soap, or cologne and not to drink alcohol, use tobacco, or eat foods with a strong odor. 

Then a separate control group of women were asked to smell the men's shirts while rating them for appeal, desirability, and strength of the smell on scales from one to 10. Women were also asked to complete surveys pertaining to their use of contraception and what stage their menstrual cycle was at.

The group's results showed that cortisol levels had no effect on the man's perceived attractiveness. However, women at their peak stage of fertility found men with higher levels of testosterone to smell more pleasurable and attractive.

The research team is unclear as to what causes this association between the smell of testosterone and attractiveness, but speculate it is has something to do with the similar bodily production of the sex pheromone, androstenol.

Is it time to buy pheremone cologne?

"This is a controversial research area. Studies are highly inconsistent," psychologist Wendy Wood of the University of Southern California, who was not involved in the study, told LiveScience in an email. "Only a few studies have shown that women's menstrual cycles influence their mate preferences — many more find no effects of menstrual cycles on preferences," Wood added. 

The team concluded that more research would be needed before a specific link to hormones and attraction can be made.