"This is the first report in humans of a natural social chemosignal that increases sexual motivation," said Martha McClintock, the David Lee Shillinglaw Distinguished Service Professor in Psychology at the University, and the lead researcher in a team at the University's Institute for Mind and Biology. Chemosignals are substances that while not necessarily perceived as odors, nonetheless have an impact on mood and menstrual cycles when absorbed through the nose.

The researchers found that after being exposed to the breastfeeding compounds for two months, women with regular partners experienced a 24 percent increase in sexual desire as reported on a standard psychological survey. Women without partners experienced a 17 percent increase in sexual fantasies after exposure for the period.

Women in the control group with partners who were exposed to a neutral substance reported an insignificant decrease in sexual desire, while women without partners in the control group experienced a 28 percent decrease in fantasies.

The work on sexual desire is reported in the paper "Social Chemosignals from Breastfeeding Women Increase Sexual Motivation," being published in the latest issue of Hormones and Behavior.

Joining McClintock in writing the paper were Natasha Spencer, Sarah Sellergren, Susan Bullivant and Suma Jacob, researchers at the University of Chicago, and Julie Mennella, a scientist with the Monell Chemical Senses Center, in Philadelphia. The study was conducted both in Chicago and Philadelphia.

In Philadelphia, Mennella recruited 26 breastfeeding women, who were asked to eat a bland diet to avoid transmitting odors such as curry through the breast milk. The breastfeeding women wore pads in their nursing bras, where the saliva from their infants in
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Contact: William Harms
w-harms@uchicago.edu
773 702-8356
University of Chicago
6-Oct-2004