Are there pheromones in period blood

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. There are purely evolutionary reasons for this: our animal instincts to procreate. 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.

Basically, ovulation beats genetics! So, why were the women not allowed to use hormonal contraception? This is understandable, because most pills contain an artificial form of the hormone progesterone, which permanently prevents ovulation. Related Articles. Why Is My Period Late? Tired of Tampons? Trending Topics. What Parents Need to Know.

One study found no significant variance across the cycle These inconclusive outcomes leave us unclear about how the nose in tune with cycle. We do know olfactory cues have subtle ways of indicating fertility and familial identification.

Parent-child bonding begins with scent and smelling. With the cycle, body odor attractiveness peaks around the time an egg is released. Does your sense of smell change across your cycle? Let us know. Track in Clue and discover patterns. Are vaginal fluids really all that different? In this article, we explain how to identify vaginal discharge, arousal fluid, and cervical fluid.

Because the preliminary data analyses seemed to support this hypothesis, we added the linear DAY and quadratic DAY 2 effects of the day into the model as covariates.

No evidence on higher-order effects was found. This full model in the sense that it contains all possible interactions in the design was first estimated and evaluated.

Then we hierarchically simplified the model as far as possible by removing the nonsignificant effects one by one, starting from the most complex least significant interactions.

The model that could not be simplified any more without dropping a significant effect or violating the hierarchy principle i. The model was built in this stepwise way independently for both attractiveness and intensity. The degrees of freedom for the F tests were calculated by the method of Kenward and Roger The results of the full model significance tests for the fixed effects on the sexual attractiveness are given in Table 1.

The results in Table 2 show several significant interactions. The regressions are presented graphically in Figure 1. The main finding is that the shape of the regression curve is clearly related to the use of contraceptive pills. Some minor variation is related to the sex of the rater. The regression is significant only in the case of normally ovulating women, rated by men Figure 1a , Equation 1 above. The conflicting results from the F and t tests are not easy to interpret and may be caused by the intercorrelation of the linear and quadratic effects in the equation.

The attractiveness ratings by women for the body odors of normally ovulating women Equation 3 also reached the maximum value at The main effect of the sex of the rater as well as its interaction with the use of pills were significant Table 2 , suggesting that when the effect of the day of menstrual cycle is averaged out, male raters tend to rate the sexual attractiveness of odors higher than female raters did, the difference being larger for odors of normally ovulating women.

The use of contraceptive pills did not have a main effect on the attractiveness ratings Table 2. Thus, we found no evidence of the day, the use of pills, or the sex of the rater affecting on the intensity of odor. In our study, male raters preferred odors of women whose menstrual cycles were near ovulatory phase. This finding indicates that men can use olfactory cues to detect the reproductive status of women. Female raters showed a trend for this relationship, suggesting that women may also have the ability to detect the reproductive status of other women.

Moreover, as neither males nor females rated attractiveness of the odors of pill users according to the day of menstrual cycle, it implies that the attractiveness of women's body odors may have a hormonal basis. Although we did not measure the day of menstrual cycle of the study participants precisely e.

However, there is clinical evidence that all ovulations do not occur exactly during the midcycle, and there exists much variation in the timing of ovulation even among women with regular menstrual cycles. This may partially explain why in our study there is no steep increase in the sexual attractiveness during the midcycle. Our findings concerning male raters are in agreement with the study of Singh and Bronstad In their study, women who were not using hormonal contraceptives wore a T-shirt for three consecutive nights during their follicular ovulatory phase.

They also wore another T-shirt for three consecutive nights during their luteal nonovulatory phase. Men then rated sexiness, pleasantness, and intensity of the shirts' odors, comparing always the shirts from the same woman consecutively. Singh and Bronstad concluded that men rated the odors of shirts worn during the follicular phase as more pleasant and sexy than the odors of shirts worn during the luteal phase.

Our results extend their results to any social situation in which it is possible to judge the sexual attractiveness of body odors.

However, our results do not support the study of Thornhill and Gangestad , who used in their study a between-subject design similar to us. In their study, men rated the odor pleasantness and sexiness of T-shirts worn by women, and the ratings did not differ between the luteal and follicular phases. In the current study, neither males nor females rated attractiveness of the odors of pill users according to the day of menstrual cycle. Furthermore, because the attractiveness ratings for nonusers and pill users did not differ significantly from each other, it seems that oral contraceptives do not make odors unattractive but only demolish the cyclicity of attractiveness of odors.

However, although we are not aware of any other differences between the two groups than either using the pill or not, the pill was not subject to manipulation, leaving open the possibility that, for example, level of sexual activity was different in pill users and nonusers. Still, oral contraceptives without question affect hormonal levels of users. There are steroid hormones e. Most oral contraceptives so-called combination pills inhibit the secretion of luteinizing hormone LH and follicle-stimulating hormone FSH from the pituitary gland in the midcycle Usathanondh, This prevents ovulation and inhibits the secretion of estrogens and progesterone from the ovarian follicle and corpus luteum Nelson, However, the steroid hormones are not directly responsible for the body odor.

Humans have apocrine sweat glands e. A part of human body odors are developed when bacteria on the skin convert these steroids into odorous compounds Doty, ; Kohl and Francoeur, Thus, although there were only one steroid hormone with blood concentration that peaks strongly during or just before ovulation, it is possible that several odorous compounds are responsible for the final sexual attractiveness of body odors.

Because the intensity of odors did not depend on the day of menstrual cycle, use of oral contraceptives, or the sex of the rater, it would be tempting to conclude that the quantity of odorous compounds would be constant during the menstrual cycle and it would be only the quality of odorous compounds that changes in the normally ovulating women.

However, this conclusion is not valid because it is unknown whether the ratings for body odors were based solely on the stimulation of main olfactory epithelium. It is not necessary for pheromones to have a detectable odor, because they can be perceived also through the vomeronasal organ VNO. In other mammals other than human, stimulation of VNO with pheromones activates hypothalamic and limbic structures and results in changes of social and sexual behavior and modulation of neuroendocrine reflexes see Monti-Bloch et al.

In humans, pheromones may modulate a mood state rather than trigger a stereotyped behavioral or emotional responses Jacob and McClintock, Consequently, an interesting and still open question is whether pheromones are involved in the sexual attractiveness of body odors. We did not measure the major histocompatibility complex MHC types of the study participants.

MHC is a group of genes that is important in immune recognition and has products that also affect body odor for a review, see Penn and Potts, The reason to that preference in humans is probably inbreeding avoidance Penn and Potts, ; Reusch et al.

Another reason could be improving the heterozygosity of offspring in order to get better immunocompetence against many different parasites Penn and Potts, Accordingly, MHC preferences could have affected the ratings of individual raters in the current study. However, it seems quite unlikely that MHC preferences would have, for instance, biased ratings of sexual attractiveness for nonusers systematically toward midcycle.

The sample sizes used in our study were reasonable, and the collection of body odors was random in respect to study participants. Men could use several indirect and imperfect cues rather than one direct cue to detect ovulation see Burt, ; Buss, , Symons, For example, there exists evidence that asymmetry of women's paired soft tissue fingers, ears, and breasts is lowest on the day of ovulation Manning et al.

On the other hand, women's ability to attract men during their ovulation may be as important as men's ability to detect women's signals. Grammer showed that ovulating women were touched by men more often than were nonovulating women, and they also exposed more their skin and wore tighter and shorter clothes.

Accordingly, the relative importance of women's odors as signals of their reproductive status is currently unknown and requires well-designed experiments. No statistically significant relationship was found between odor attractiveness and day of menstrual cycle by women raters. However, the nonsignificant trend and statistical significance of linear and quadratic terms, see Results suggests that women may still be able to use olfactory cues to detect the reproductive status of other women.

Recent evidence suggests that women can use odors in their mate selection. For instance, near their ovulatory phase, women have been found to prefer the body odors of symmetrical men Gangestad and Thornhill, ; Rikowski and Grammer, However, at present we have no obvious adaptive explanation supporting the interpretation that also females could detect the reproductive status of other women.

If the ability of a woman to detect ovulation has no costs for the bearer and it has coevolved with men's ability, it could have survived during evolution.

Still, communication through pheromones can also work in female-female interactions Stern and McClintock, and clearly deserves more study. To conclude, our results support the view that the body odors of an ovulating woman increase her attractiveness to men.