Synthetic hormones in contraceptives have been a focus of scientific inquiry regarding their influence on human behavior, particularly attraction. Hormonal contraceptives (HCs), such as the pill, patch, and ring, prevent ovulation by introducing synthetic versions of estrogen and progesterone. The central question is whether these compounds, which override the body’s natural cycle, interfere with the subconscious signals that guide partner choice. Research suggests that by mimicking a constant hormonal state, HCs may alter the biological mechanisms that inform attraction, potentially impacting mate preference and sexual desire.
Hormones, Pheromones, and the Basis of Natural Attraction
The natural menstrual cycle involves significant fluctuations in estrogen and progesterone, contributing to reproductive status. Estrogen levels surge leading up to ovulation, the most fertile phase of the cycle. This hormonal peak is linked to changes in attraction preferences, often favoring men who display traits signaling high genetic quality, such as facial masculinity or body symmetry.
The body also communicates reproductive fitness through chemical signals called pheromones, odorless compounds often perceived subconsciously. In naturally cycling women, these pheromones contribute to a preference for the scent of genetically dissimilar men. This preference is an evolutionary mechanism ensuring offspring have a more robust and diverse immune system. The natural hormonal ebb and flow optimizes mate selection by temporarily heightening attraction to specific genetic traits during the fertile window.
How Contraceptives Alter Mate Preference and Genetic Compatibility
Hormonal contraceptives suppress the natural rise and fall of hormones, creating a hormonal environment similar to pregnancy or the non-fertile phase. This change flattens the cyclic shifts in preference that non-users experience, such as the increased attraction to masculine features around ovulation. Studies show that women using HCs may exhibit a reduced preference for male facial masculinity.
A highly studied area involves the Major Histocompatibility Complex (MHC), a group of genes linked to immune system function and body odor. Typically, women are drawn to the scent of men with MHC genes dissimilar to their own, promoting genetic diversity in offspring. However, some research suggests that women using HCs may reverse this preference, showing attraction to men with similar MHC profiles. This shift is theorized to occur because the body, mimicking pregnancy, prioritizes partners who smell genetically similar, potentially signaling a supportive relative for child-rearing. Choosing a partner with a similar MHC profile may lead to lower sexual responsiveness or satisfaction, though a direct causal link requires ongoing research.
The Separate Effect on Sexual Desire and Libido
While attraction preference determines who a person is drawn to, sexual desire or libido relates to how much sex a person wants. Hormonal contraceptives can reduce libido through a distinct physiological mechanism involving sex hormone-binding globulin (SHBG). SHBG is a protein that binds to sex hormones, including testosterone, making them biologically inactive.
HCs, particularly combined oral contraceptives, cause a significant increase in SHBG production. This rise effectively lowers the amount of free, circulating testosterone available to drive sexual desire, as testosterone modulates female sexual function. The suppression of ovarian testosterone production by HCs acts as a second mechanism to reduce androgen levels. This effect is highly individualized; some women report a decrease in desire, while others experience no change or an increase.
Reverting Attraction Preferences After Stopping Hormonal Contraception
A common question is whether these preference changes are permanent or if they revert once synthetic hormones are cleared from the system. When a person discontinues hormonal contraception, the natural ovulatory cycle and its associated hormone fluctuations typically resume. The suppression of natural hormones ceases, allowing the body’s pre-HC biological signals, including pheromonal preferences for MHC dissimilarity, to reassert themselves.
Studies show that after stopping HCs, women may experience an increase in both sexual desire and attraction toward their partner. For women who chose a partner while on HCs, the return to natural hormone levels can sometimes lead to a shift in their perception of the partner. If a partner was chosen under the influence of the pregnancy-mimicking hormonal state, the return of natural preferences may result in a decrease in attraction and, in some cases, lower relationship satisfaction. Elevated SHBG levels may take several months to decrease, but as they do, free testosterone levels and sexual function improve.