Large International Study Finds Little Evidence That Changing Hormonal Birth Control Affects Relationships

Changing hormonal birth control during a relationship does not appear to reduce a woman's love, commitment or overall satisfaction with her partner, according to a large international study. The findings challenge a long-standing theory suggesting that starting or stopping hormonal contraception after meeting a partner could alter romantic attraction and gradually weaken relationships.

The study, conducted by researchers from the University of Wrocław and the University of Stirling, analyzed data from women in 51 countries and found little evidence that changing contraceptive use meaningfully affects relationship quality. Instead, the results suggest that, for most women, factors such as communication, compatibility and everyday relationship dynamics are likely to have a much greater influence than hormonal contraception itself.

Why scientists have questioned the role of hormonal contraception

Hormonal contraceptives, including birth control pills, patches and hormonal intrauterine devices (IUDs), prevent pregnancy primarily by suppressing ovulation and reducing the natural hormonal fluctuations that occur throughout the menstrual cycle.

Because these medications also influence hormones and neurotransmitters involved in mood, bonding and sexual desire—including estrogen, progesterone, testosterone and oxytocin—researchers have long debated whether they might subtly influence romantic relationships.

One influential explanation has been the ovulatory shift hypothesis, which proposes that women's partner preferences naturally change across the menstrual cycle. During the fertile phase, women may place greater value on traits associated with masculinity and genetic quality, while at other times they may prioritize warmth, reliability and long-term partnership qualities.

Building on this theory, researchers later proposed the Congruency Hypothesis, which suggests that relationship satisfaction may be highest when a woman's hormonal contraceptive status remains consistent throughout the relationship. According to this idea, starting or stopping hormonal contraception after choosing a partner could alter attraction by changing underlying partner preferences.

Researchers tested the theory across 51 countries

Previous studies examining the Congruency Hypothesis have produced conflicting results and were conducted mainly in Western countries. To determine whether the theory held across more diverse populations, psychologists Marta Kowal and S. Craig Roberts and their colleagues analyzed data collected from semi-representative samples in 51 countries spanning multiple cultural and geographic regions.

The researchers initially gathered responses from 10,482 participants and then focused on 2,224 women aged 45 years or younger who were currently in romantic relationships.

Participants reported whether they were using hormonal contraception when they first met their partner and whether they were using it at the time of the survey. This allowed researchers to determine whether contraceptive use had remained consistent throughout the relationship or had changed over time.

Among the participants, 1,611 women reported consistent contraceptive use, while 613 had either started or stopped hormonal birth control after entering their relationship.

Measuring different aspects of love

To evaluate relationship quality, participants completed a 15-item questionnaire based on psychologist Robert Sternberg's Triangular Theory of Love.

Rather than measuring only general satisfaction, the questionnaire examined three separate components of romantic relationships:

• Intimacy, reflecting emotional closeness and connection.
• Passion, capturing romantic and sexual attraction.
• Commitment, representing the decision to maintain the relationship over time.

Researchers also collected information about relationship length, marital status, education and income so these factors could be considered during statistical analyses.

Changing contraception showed little impact

Across nearly all analyses, the researchers found no convincing evidence that changing hormonal contraceptive use harmed relationships.

Women who started or stopped hormonal birth control after entering a relationship reported levels of intimacy, commitment and overall relationship satisfaction that were remarkably similar to those whose contraceptive use had remained unchanged.

Likewise, women who were currently using hormonal contraception did not report being less satisfied or less in love than women who were not using hormonal methods.

One statistical model suggested that women whose contraceptive status had changed reported a very small reduction in passion—approximately 1.6 percent on average. However, this finding disappeared in other analyses, leading the authors to conclude that the result should be interpreted cautiously rather than viewed as reliable evidence of a meaningful effect.

Overall, the study found little support for the Congruency Hypothesis as an explanation for relationship satisfaction.

Why researchers remain cautious

Although the findings are reassuring, the researchers emphasize that the study has important limitations.

Because the research was cross-sectional, all information was collected at a single point in time. This means the study cannot determine whether changing contraception directly influences relationships or whether other factors explain any observed differences.

Another possible limitation is selection bias. Women who experience unpleasant side effects from hormonal contraception may discontinue treatment, while women who continue using it may generally tolerate it well. Differences in mental health, sexual desire, reproductive goals or attitudes toward contraception could therefore influence the results independently of hormonal effects.

The researchers also relied on participants' memories when asking whether they were using hormonal contraception when they first met their partner. Although relatively few women reported uncertainty, some degree of recall error is unavoidable.

The authors note that recent meta-analyses similarly suggest that if hormonal contraception affects relationship quality at all, the effect is likely to be extremely small.

Large international differences

The study also highlighted substantial variation in contraceptive use between countries.

Among women included in the research, approximately 71 percent of participants in Honduras reported currently using hormonal contraception, compared with only around 3 percent in India.

The researchers say these differences almost certainly reflect variations in healthcare access, education, cultural norms, religious beliefs and national reproductive health policies rather than biological differences between populations.

Such factors are important because they influence not only contraceptive use itself but also women's reproductive choices and experiences.

What the findings mean for women

The authors stress that their results should not be interpreted as proof that hormonal contraception never influences mood, libido or individual relationships.

Some women do experience side effects, including mood changes or reduced sexual desire, and healthcare providers should continue considering these individual experiences when discussing contraceptive options.

However, the findings suggest that widespread claims circulating online—that starting or stopping hormonal birth control fundamentally changes who women love or dramatically undermines romantic relationships—are not supported at the population level.

The researchers recommend future long-term studies following women before and after changing contraceptive methods to better understand individual differences over time.

For now, this large international study offers reassuring evidence that changing hormonal birth control is unlikely to substantially alter relationship satisfaction for most women. Instead, the quality of a relationship appears far more likely to depend on communication, trust, compatibility and shared life experiences than on whether hormonal contraception has changed during the course of the relationship.