The Scent of a Woman: How Reproductive Hormones Influence Body Odour Attractiveness

Summary: Researchers from the University of Bern report that reproductive hormones not only regulate fertility but also influence how attractive a woman’s natural scent is to men.

Source: University of Bern.

Overview

Reproductive hormones orchestrate a woman’s menstrual cycle and overall fertility. New research from the University of Bern shows these same hormones are linked to differences in how attractive women smell to men. The study demonstrates that some women’s natural body odour is more appealing than others, and that this variation corresponds to hormone levels associated with high reproductive fitness.

Smell as a Factor in Mate Choice

Humans rely on multiple sensory cues when evaluating potential partners. While visual signals are often emphasized, scent also plays a meaningful role in human mate selection—just as it does across the animal kingdom. Previous work has shown that a woman’s scent varies across her menstrual cycle, typically becoming more attractive during her most fertile days. The recent study asked an additional question: beyond cycle-related fluctuations, do some women consistently smell more attractive than others?

A research team led by Daria Knoch from the Social Psychology and Social Neuroscience Department at the University of Bern, in collaboration with colleagues from the University of Konstanz, the Thurgau Institute of Economics and the Inselspital Bern University Hospital, investigated this question. Their results show clear agreement among male raters: certain women’s body odours were consistently judged more attractive than others.

Key Finding: Reproductive Hormones Predict Odour Attractiveness

The central finding is that levels of female reproductive hormones predict how attractive a woman’s scent is to men. Women with higher oestradiol (estrogen) and lower progesterone were rated as having more attractive body odour. As the authors note, this pattern aligns with evolutionary theory: high oestradiol and relatively low progesterone are hormonal signatures of increased fertility, and scent may provide a chemosensory cue to that fertility.

The researchers tested other possible biological influences on odour, including the stress hormone cortisol and immune-related genetic markers. Some theories propose that dissimilar immune system genes between partners can improve offspring immune defenses, and that odour could signal such differences. In this study, however, cortisol and the genetic immune markers measured did not predict body odour attractiveness.

Study Design and Methods

The experiment involved 28 healthy, naturally cycling women who provided body odour samples and 57 male raters who evaluated those samples. To capture genuine individual odours and reduce confounding factors, the women followed a strict collection protocol: no hormonal contraception, no sharing of beds during odour collection, neutral detergents for washing body and bed linens, and avoidance of alcohol and spicy foods around sampling times. At peak fertility, cotton pads were placed in the women’s armpits overnight to collect scent samples. Saliva samples taken at the time of odour collection were used to measure levels of oestradiol, progesterone, testosterone and cortisol. Later, male participants sniffed the pads in the lab and scored each sample on a 0–100 scale.

Interpretation and Context

Lead author Janek Lobmaier explains that reproductive hormones function as indicators of fertility and that odour likely serves as a valid chemosensory cue. The study supports the idea that men are sensitive to scent cues tied to female reproductive status and that some women’s odours convey greater attractiveness because they reflect hormonal profiles associated with higher fertility.

Daria Knoch adds that while this study focused on naturally cycling women, it did not directly test how hormonal contraception affects odour attractiveness. Prior research suggests hormonal contraception can alter a woman’s natural scent; the authors reiterate that contraceptives may disrupt typical odour cues, but this study did not experimentally address that question.

Publication and Authors

This research was authored by Janek S. Lobmaier, Urs Fischbacher, Urs Wirthmüller, and Daria Knoch and published in Proceedings of the Royal Society B. The paper is titled “The scent of attractiveness: levels of reproductive hormones explain individual differences in women’s body odour.” DOI: 10.1098/rspb.2018.1520. The work was organized and reported by NeuroscienceNews, with originating research conducted at the University of Bern.

Abstract (Summary)

The study examined whether individual differences in women’s body odour are universally perceived as more or less attractive and whether those differences are explained by reproductive hormone levels. Fifty-seven men rated body odours from 28 naturally cycling women collected at peak fertility. Salivary oestradiol, progesterone, testosterone, and cortisol were measured. Men showed strong agreement in attractiveness ratings. Crucially, body odour attractiveness was predicted by oestradiol and progesterone: higher oestradiol and lower progesterone corresponded to higher attractiveness ratings. Cortisol and testosterone did not predict odour attractiveness. These results indicate that female body odour can act as a chemosensory cue to potential fertility.

Source: University of Bern
Publisher note: Organized and reported by NeuroscienceNews.
Image credit: NeuroscienceNews.com image in the public domain.
Original research: “The scent of attractiveness: levels of reproductive hormones explain individual differences in women’s body odour” by Janek S. Lobmaier, Urs Fischbacher, Urs Wirthmüller, and Daria Knoch. Proceedings of the Royal Society B. Published September 12, 2018. DOI: 10.1098/rspb.2018.1520.