The study by psychological scientists Saul L. Miller and Jon K. Maner from Florida State University involved 68 male undergraduate students ages 18 and 23 years. The men were asked to smell T-shorts worn by women for three nights during various phases of their menstrual cycle.

The researchers then proceeded to measure testosterone levels in the saliva of these men. A control group were asked to smell T-shorts that had not been worn by any female. The testosterone levels of the control group was also tested.

Men who smelled the T-shirts of ovulating women had significantly raised levels of testosterone as compared with men who were made to smell an ordinary T-shirt.

"Men exposed to the scent of an ovulating woman subsequently displayed higher levels of testosterone than did men exposed to the scent of a non-ovulating woman or a control scent," the authors write. “The relatively higher testosterone levels arising from exposure to ovulatory scents suggests that those scents might lead men to respond with greater mate-seeking behaviors than they would otherwise.”

The details of the study are published in Psychological Science.

An earlier study had indicated that the presence of complex pheromones in the underarm sweat of men attracted a woman and even lets her decide if the man is the one for her . The new study shows that a similar effect may be seen in men during the time of a woman's ovulation when she is at the peak of her fertility during the month.