In fact, underarm sweat contains a complex compound of odourless pheromones that have a powerful subconscious effect on females, according to researchers at Monell Chemical Senses Centre in Philadelphia.

In their study, the researchers found that the exposure to the pheromone from the male armpit accelerated the release of the luteinizing hormone which controls menstruation in women, the news.com.au reported.

Even the female test subjects admitted that they felt increasingly relaxed as they sniffed the hormone. As mentioned -- it's odourless.

According to the researchers, the finding may one day lead to the development of new fertility drugs. They have also speculated that men's fragrances can contain male pheromones, which would presumably be irresistible to any woman.