Female birth control comes in many forms such as birth control pills,patches, shots and more. However in the end they all work the same. The way birth control works is that it stops the ovulation period of a woman in which the mature egg is prepared. Without the preparation of the mature egg, pregnancy is not possible.
A study by Florida State university published an article in the Journal Psychological Science. Stating that men were more attracted to women during their ovulation period, a period that birth control prevents
The study was performed with 2 groups of women. Those on birth control pills and those not on the pill. During their ovulation period for 3 days, they were instructed to wear a single T-shirt. They were prohibited from wearing any scented products like perfume, deodorant or antiperspirants and when showering to not use any scented product. They were not even allowed to share a bed with another man or woman.
This was to ensure that any scent coming from the shirt was simply their own. After 3 days the women returned to the lab and the T-Shirt were collected and put in a freezer until the male participants could arrive.
Each of the women’s shirt were sniffed by the men and following this the man’s saliva was tested for testosterone levels. Testosterone levels increase during sexual attraction which is why it was being tested.
The discovery made was that the testosterone levels of the men that smelled the shirts of the women not on birth control was much higher than when they smelled the shirt of the women on birth control.
Naturally, the men did not know the reason because this happens on a primal subconscious level but when asked their thoughts of the smell of the shirt. They said the shirts of the way who were ovulating smell was more pleasant.
Another study was published in 2007 in the journal Evolution and Human Behavior. The study was done with lap dancers. The groups were the same, women who were ovulating and those who were not. The woman who were most fertile/ovulating made on average more tips than the women who were not ovulating.
Note that also during this phase, women tend to act and dress differently. Their sex drive gets amped. They begin showing more skin, wearing tighter clothes, taking special care of their make up application and even adding more sway to their butts when walking. An attempt to draw more attention to her self from men.
This makes sense, because our primal core of wanting sexual intercourse is to reproduce. Especially in our caveman days and knowing when a woman was most fertile was an important skill to ensure that reproduction was/is a success.