Claim: “Birth control makes women less attracted to masculinity”

Accuracy Assessment: Largely True

The core claim — that hormonal contraception reduces women’s attraction to masculine male traits on average — is directionally supported by multiple lines of research, but the picture is considerably more complicated than the popular-science framing suggests. The evidence is genuine but contested, the effect sizes are variable, and some well-powered recent studies find no effect at all for specific measures such as facial masculinity preference.

What the research broadly shows is this: naturally cycling women show mid-cycle (peri-ovulatory) surges in preference for masculine physical traits, dominant behaviours, and MHC-dissimilar body odour — changes that are absent or suppressed in hormonal contraceptive users, who maintain a more stable, lower-baseline preference.¹²³ Several longitudinal studies confirm that starting the pill reduces preference for masculine faces⁴ and shifts olfactory preferences from MHC-dissimilar (genetically complementary) towards MHC-similar partners.⁵ Downstream relationship data reinforce the picture: women who began relationships while on the pill, then stopped, reported lower marital satisfaction with less facially attractive husbands and showed heightened attraction to masculine “bad boy” alternatives during the fertile phase of their cycle.⁶⁷

However, a 2019 large-scale study of 6,482 women found no difference in facial masculinity preference between pill users and non-users⁸, and a 2024 double-blind randomised controlled trial (n = 340) found no effect of oral contraceptives on preferences for masculine or symmetrical male faces.⁹ These are serious challenges to the facial-masculinity component of the claim. What survives more robustly is the suppression of ovulatory-cycle-driven peaks in attraction to masculinity and the MHC-odour preference shift. The claim is therefore Largely True with an important caveat: the effect is real for broad attraction patterns and odour-based preferences, but weaker and more contested for facial masculinity specifically.

Key Claims at a Glance

Claim Breakdown

1. “Naturally cycling women show mid-cycle peaks in preference for masculine traits”

✅ Largely True — well-replicated across multiple domains, though not without controversy

The ovulatory shift hypothesis proposes that women evolved to shift mate preferences across the menstrual cycle: near ovulation (high fertility), they prefer markers of genetic quality — facial masculinity, dominance, symmetry, deep voices, and MHC-dissimilar body odour — while at other times (when conception is unlikely) they prefer cues of long-term investment.¹ This forms the necessary background to evaluate the birth-control claim: if hormonal contraception eliminates the mid-cycle hormonal peak (which it does, by suppressing ovulation), any real cyclic preference shift will be flattened.

A 2023 PMC review³ summarised the evidence across more than a decade of studies, finding that peri-ovulatory shifts in masculinity preference had been replicated across faces, voices, body shapes, dominant behavioural profiles, and odour cues. The effect is not confined to a single lab or measure. Critics note that some studies used small samples and self-reported cycle data, which introduces error; large-scale longitudinal studies using measured hormones have found weaker effects. A 2020 Hormones and Behavior study found “no compelling robust evidence for mate preference shifts” across the cycle using hormone measurements¹⁰. The Wikipedia summary of the ovulatory shift hypothesis itself notes the controversy².

The middle-ground position supported by the weight of evidence is that cyclic shifts are real but modest, moderated by individual differences, and reliably demonstrated in short-term (but not necessarily long-term) partner evaluation contexts.

Verdict: ✅ Largely True — cycles do produce preference shifts in most studies; the literature is contested but the overall weight of evidence favours their existence.

2. “Pill users show weaker preference for masculine male faces”

🟡 Contested — early positive findings challenged by larger, better-controlled studies

This is the most directly tested and most controversial sub-claim. The research history is a textbook example of how psychology findings can initially appear robust, then erode under pre-registered replication.

Evidence supporting the effect:

• Little et al. (2013) tested women before and three months after starting the pill. After pill initiation, women preferred significantly less masculine faces for both short- and long-term relationships.⁴ The study also found that men whose partners had been on the pill when they first met were rated as less masculine than men whose partners were not on the pill — suggesting the preference translates to real-world partner choice.
• A 2009 review in Trends in Ecology & Evolution by Roberts & Gosling noted that pill users “show no or weaker preferences for facial and vocal masculinity” compared with normally cycling women.¹
• Multiple earlier studies replicated this pattern with various face-manipulation paradigms.

Evidence against the effect:

• Marcinkowska et al. (2019) compared 1,857 pill users against 4,625 non-users in a large online study. They found no evidence that pill users had weaker preferences for masculine faces.⁸ A large-scale study finding nothing is harder to dismiss than a small-scale study finding something.
• Ranehill et al. (2024) conducted a double-blind randomised controlled trial with 340 women. Despite confirming that the pill produced the expected hormonal changes (lower LH, FSH, testosterone, and estradiol), they found no statistically significant differences in preferences for facial masculinity or symmetry between the pill group and the placebo group.⁹ This is the most methodologically rigorous study to date and finds nothing.
• The Collabra: Psychology review (2021) noted that large-scale studies consistently find limited evidence linking steroid hormones to facial masculinity preferences.¹⁰

The earlier positive findings are likely a combination of small-sample false positives, publication bias, and flexible analytical strategies. The more rigorous evidence points to no facial masculinity preference effect. This sub-claim, in its facial-preference form, is contested and weakening.

Verdict: 🟡 Contested — earlier studies found an effect; larger and randomised studies do not. The facial masculinity preference component is the weakest part of the overall claim.

3. “Birth control shifts odour preferences away from genetically complementary partners”

✅ Largely True — longitudinal evidence from multiple studies

This is arguably the strongest mechanistic evidence for the claim. The major histocompatibility complex (MHC) is a set of immune-related genes. Normally cycling women tend to prefer the body odour of MHC-dissimilar men — a preference that promotes offspring immune heterozygosity and reduces inbreeding.⁵ The pill appears to reverse or suppress this preference.

Roberts et al. (2008)⁵, in a longitudinal within-subjects design, had women rate six male body odour samples both before and after initiating pill use, with a control group of non-users tested twice over a comparable period. Key findings:

• Pre-pill use, no significant MHC-based odour preferences were found in the overall sample.
• After pill initiation, there was a significant shift towards preferring MHC-similar odours among the pill-using group — a shift not seen in the control group.
• The pill group also showed lower between-session repeatability in pleasantness and desirability ratings, suggesting destabilised preferences.
• Relationship status moderated baseline preferences: partnered women preferred MHC-dissimilar odours, while single women preferred MHC-similar odours. Women who shared fewer alleles with their partner reported greater attraction to extra-pair men.

This is concerning from a relationship-stability perspective: a woman who chooses a partner based on pill-mediated preferences (MHC-similar rather than MHC-dissimilar) may find herself less attracted to him if she later stops taking the pill, since she would now prefer a genetically complementary (dissimilar) scent.

Wedekind’s original 1995 “sweaty T-shirt” study reported the same pattern, and subsequent studies have generally replicated the MHC-odour shift, though with varying strength. This strand of evidence is more consistent than the facial-masculinity literature.

Verdict: ✅ Largely True — the MHC-odour preference shift is supported by a longitudinal within-subjects design and is consistent with the established biology of olfactory mate choice.

4. “Women who met partners while on the pill, then stopped, experience relationship dissatisfaction”

✅ Largely True — supported by two longitudinal marriage studies and behaviour research

If the pill genuinely alters mate preferences during partner selection, one would predict downstream consequences when women stop taking it: their naturally re-emerging preferences might not match their chosen partner. Two lines of evidence support this.

Marital satisfaction study (Russell et al., 2014):⁶

A two-part longitudinal study of married couples found that wives who had used hormonal contraceptives at the time they began their relationship became less satisfied with their marriages after discontinuing HCs — but only if their husbands were less facially attractive. Women who had chosen more attractive husbands while on the pill were fine after stopping; it was women who had chosen less attractive (and presumably less genetically appealing) men whose satisfaction dropped. This interaction precisely matches the prediction from the mate-preference-shift hypothesis.

Behavioural study (Mojtahedi et al., 2019):⁷

Women who had used pills at relationship formation but had since stopped were more likely — during their fertile phase — to express sexual desire for a “bad boy” (attractive, masculine, low-dependability) over an “ordinary guy.” A replication using an attentional cueing task found the same pattern using implicit rather than explicit preferences. This suggests that once the pill’s hormonal suppression is lifted, latent preferences for masculine, genetically appealing partners resurface and compete with the existing relationship.

This is not trivially caused by the pill alone; confounding by women who have different baseline preferences self-selecting into pill use is hard to exclude in observational studies. But the interaction with partner facial attractiveness in the Russell et al. study is hard to explain without invoking a genuine preference-shift mechanism.

Verdict: ✅ Largely True — converging evidence from marital data and behavioural studies shows the predicted downstream relationship effects, consistent with pill-induced preference changes at partner selection.

5. “The effect is strong enough to influence real-world partner choice”

🟡 Contested — correlational evidence is suggestive but causation is not confirmed

The Little et al. (2013) study⁴ showed that men whose partners were on the pill when they first met were rated as less masculine by independent raters than men whose partners were not on the pill. This is a real-world correlate of the lab findings. However, this study is correlational: women who choose to use hormonal contraceptives may systematically differ from those who do not (age, relationship status, personality, sexual activity patterns) in ways that also predict partner masculinity preference independently of the pill.

The Collabra 2021 review¹⁰ explicitly raised this concern — calling it “unobserved selection” — noting that without randomisation it is difficult to attribute observed partner-choice differences to the pill rather than to pre-existing differences between pill users and non-users. This criticism has real force. The RCT by Ranehill et al.⁹ is the logical solution, but it only ran for three months, which is too short to observe real-world partner selection.

The honest position is: there is suggestive correlational evidence that women on the pill end up with less masculine partners in real life, and this is theoretically explicable by the preference-shift mechanisms described above. But it has not been demonstrated experimentally with appropriate controls for the full partner-selection process.

Verdict: 🟡 Contested — the real-world signal exists but causal attribution is not confirmed; unobserved selection remains a plausible alternative explanation.

Summary Table

Overall: ✅ Largely True — The claim that birth control reduces women’s attraction to masculinity is directionally supported by the weight of evidence. The pill suppresses the ovulatory peaks that normally drive heightened attraction to dominant, masculine, and genetically complementary traits. The MHC-odour preference shift is well-evidenced; the facial masculinity preference shift is more contested. Real-world consequences for relationship satisfaction after pill discontinuation add practical weight to the claim. The claim is not “False” — it reflects a real biological mechanism that has been studied for decades — but the strength of the facial-attractiveness component specifically has weakened under more rigorous scrutiny.

References

Trends in Ecology & Evolution — Contraceptive pill and mate choice review (2009)

PLoS ONE — No evidence of facial masculinity preference change in pill users (Marcinkowska et al., 2019)

The Atlantic — "Women on Birth Control Pills Prefer Less Masculine Men" (Little et al., 2013)

PsyPost — Birth control pills do not alter women's preferences for masculine faces (RCT, 2024)

PMC — MHC-correlated odour preferences and oral contraceptives (Roberts et al., 2008)

PMC — Hormonal contraceptives and marital satisfaction (Russell et al., 2014)

Psychology Today — Do contraceptive pills affect attraction? (Mojtahedi, 2019)

PMC — Menstrual cycle shifts and masculinity preferences review (Jones et al., 2023)