Hormonal birth control (BC), including the pill, patch, ring, and hormonal intrauterine devices, works by introducing synthetic hormones that primarily prevent ovulation. While the intended effect is pregnancy prevention, altering the body’s natural hormone balance may have unintended consequences on psychological and behavioral traits. A growing body of research suggests these hormonal shifts can change who a person is attracted to. This idea touches on the fundamental biological drivers of human mate choice.
The Natural Hormonal Drivers of Attraction
In the absence of hormonal contraception, attraction preferences are not static; they fluctuate according to the stages of the natural menstrual cycle. The cycle is divided into phases characterized by shifting levels of reproductive hormones, which influence a person’s biological priorities. During the follicular phase, estrogen levels rise dramatically, leading up to ovulation and the peak window of fertility.
This high-estrogen phase is associated with a preference for partners who exhibit markers of genetic quality. Women are more attracted to men displaying pronounced masculine traits, such as deeper voices and symmetrical facial features. This attraction is thought to be an evolutionary mechanism designed to select for partners with good genes when the chance of conception is highest.
The Major Histocompatibility Complex (MHC) is also a biological driver of attraction, involving a set of genes related to immune function. Naturally cycling people often show a subconscious preference for the scent of partners with dissimilar MHC genes, signaled through body odor. Choosing a partner with a different MHC profile maximizes the genetic diversity of offspring, providing them with a more robust immune system. Once ovulation passes, the preference shifts toward partners who signal stability, resources, and commitment, rather than purely genetic quality.
How Hormonal Contraceptives Shift Partner Preference
Hormonal contraceptives alter the natural cycle by providing a steady, exogenous dose of synthetic hormones, typically progestin and a form of estrogen. This hormonal state suppresses ovulation and mimics the endocrine profile of the luteal phase or pregnancy. By flattening the hormonal peaks and valleys, hormonal BC eliminates the mid-cycle estrogen surge that drives attraction toward highly masculine traits.
Women on hormonal BC show a consistent preference for men who display less pronounced masculine features compared to naturally cycling women. This state of non-fertility is associated with a greater focus on long-term partnership qualities. This shift prioritizes characteristics like reliability and resource-provisioning over immediate genetic indicators.
The influence of hormonal BC extends to the genetic drivers of attraction, such as the MHC preference. By suppressing natural hormonal fluctuations, hormonal BC may interfere with the ability to detect and prefer genetically dissimilar partners. Some studies suggest that women who start hormonal BC may be more likely to select partners with MHC profiles that are more genetically similar to their own. This preference for genetically similar partners is the opposite of the natural drive during peak fertility.
Relationship Stability and Stopping the Pill
The potential for altered attraction patterns can have real-world consequences for relationship satisfaction, particularly when the use of hormonal contraception changes over time. Many people meet their partners while using hormonal BC and later discontinue it, often with the intention of trying to conceive. The cessation of the pill allows the natural hormonal cycle to resume, potentially restoring the attraction drivers that were suppressed for years.
This return to a natural cycle can trigger a “Pill-Stopping Effect.” For women who chose a partner while on hormonal BC, the renewed attraction to more masculine or genetically dissimilar traits can cause a change in feelings toward their current partner. Studies of newlywed couples have shown that women who stopped using hormonal BC after forming their relationship reported decreased marital satisfaction, particularly if their husband had a less attractive face.
Conversely, if a woman on hormonal BC chose a partner who was already highly attractive or masculine, discontinuing the pill may lead to an increase in attraction for that partner. This highlights the possibility of a hormonal mismatch when the initial choice was made under an altered endocrine state. The hormonal environment during mate selection may play a role in long-term satisfaction once that environment changes.
Effects on Libido and Sexual Function
Beyond changing who a person is attracted to, hormonal contraception can also impact overall sexual desire and function. This is a separate effect from mate preference and is often linked to the way synthetic hormones interact with androgens, such as testosterone. Hormonal BC, particularly combined oral contraceptives, can cause an increase in the production of Sex Hormone-Binding Globulin (SHBG) in the liver.
SHBG binds to sex hormones, including testosterone, making them biologically inactive. This process can lead to significantly lower levels of free, active testosterone in the body, a hormone associated with sexual motivation and desire. A reduction in free testosterone is the mechanism for the decrease in libido, arousal, and lubrication experienced by some users of hormonal BC.
The effect on libido is highly individual, and many users report no change or even an increase in sexual desire, often due to the reduced anxiety over unintended pregnancy. Psychological factors also play a large role in sexual function. The impact varies depending on the specific type and dose of hormones in the contraceptive method.
Non-Hormonal Methods and Attraction
Non-hormonal methods offer an alternative without endocrine interference. These methods work purely by creating a physical barrier or a non-hormonal environment that prevents fertilization, such as barrier methods like condoms and diaphragms. Since these methods do not affect the body’s hormone levels, they do not suppress ovulation or alter the natural fluctuation of estrogen and progesterone.
Similarly, the copper intrauterine device (IUD) works by releasing copper ions that are toxic to sperm, without involving the endocrine system. The user’s hormonal drivers of attraction remain intact. The preferences for masculine traits and genetically dissimilar partners are therefore free to cycle naturally, unaffected by the contraceptive choice.