When you cuddle up close to your partner in bed at night, sometimes you notice that they just smell so good – and by that we don’t mean perfume or aftershave but rather their natural scent. Musky and masculine or fresh and feminine. It is said that the human body produces chemical signals, called pheromones and these scents affect how one person perceives another and how they react to them.
This evolutionary trick even goes a step further when it comes to choosing a partner with which to have children. Studies suggest that another person’s smell is subconsciously decisive when selecting a partner with whom you want to start a family.
How estrogen causes changes in a woman’s scent.
According to swiss scientists the female hormone estrogen influences the scent of a woman. Estrogen production increases during the fertile window in order to stimulate ovulation. The altered hormone levels are reflected in the woman’s body odor.
The fact that women smell more attractive to men on their fertile days, was proven by a study at the University of Berne. The 28 women and 57 men involved in the study had to follow a very strict protocol: They were not allowed to use hormonal contraception, wash themselves with perfumed shower gel or sleep in a bed with another person. In addition, the women had to stick cotton wool pads under their arms, which absorbed their scent and were then “presented” to the men. Blood samples were taken to establish where they were in their menstrual cycles.
The result: women who were close to ovulation were perceived to smell more attractive to the men. The higher the estrogen levels in the women’s blood, the better the scent was judged to be. There are purely evolutionary reasons for this: our animal instincts to procreate. This attractive scent is nature’s way of letting men know that a woman is fertile and ready to reproduce.
Interestingly, the study also showed that the genetic factor (her personal smell) does not pay a major role in a man’s choice of partner. We have always heard that your partners smell is decisive because you are intuitively assessing their genetic compatibility and health – whether they would be a good reproductive partner. The results of the Swiss study however, showed that the men did not judge the attractiveness of the women by their smell per se, but rather by their hormone status, reveled by their smell at that time. So, a woman’s personal body scent might not play a major role for a man when choosing a partner, but it certainly does when it comes to “taking advantage” of ovulation and of passing on his genes. Basically, ovulation beats genetics!
Artificial hormones and a women’s scent.
So, why were the women not allowed to use hormonal contraception? It is thought that the pill and other hormonal contraceptives can falsify a woman’s personal smell. This is understandable, because most pills contain an artificial form of the hormone progesterone, which permanently prevents ovulation. Progesterone is the dominant hormone in the second half of a woman’s cycle, after ovulation. At the same time the pill keeps the estrogen levels permanently low. Too much progesterone and too little estrogen: the male volunteers in the swiss trial did not find this combination to be particularly attractive either by the way!
Have you ever heard the theory that women who are on the pill often choose the “wrong partner” – and when they stop taking the pill, they can’t bear the smell of them? It sounds very far-fetched, and in fact, while studies have shown a slight link, the evidence is simply too sketchy to reach a definitive verdict. So, don’t worry; your relationship is not doomed to failure just because you are using hormonal contraception.
And what about during your period?
Previous studies have shown that a woman’s body odor is strongest during menstruation and that men who are particularly sensitive to smells can even detect this change in her scent. But this is the exception rather than the rule and of course we are talking about a woman’s scent which has nothing to do with personal hygiene or body odor in that sense. It is a very subtle chemical signal which hints at whether you are currently fertile or not.
The influence your hormones have on your body is truly amazing! However, relying on your partners sense of smell to identify when you are most likely to get pregnant might not be such a great idea; it is after all entirely subconscious. We would recommend you use femSense to identify your most fertile days. The sensor in the femSense patch uses another signal from your body to tell you that you are ovulating – a rise in body temperature. That way you will know exactly where you are in your cycle without your partner having to sniff it out 😉.