Women's sexual experience during the menstrual cycle: identification of the sexual phase by noninvasive measurement of luteinizing hormone

Journal of Sex Research, Feb, 2004 by Susan B. Bullivant, Sarah A. Sellergren, Kathleen Stern, Natasha A. Spencer, Suma Jacob, Julie A. Mennella, Martha K. McClintock

Recruitment and Blinding Procedures

After a structured telephone screening, each participant came to the laboratory for training in tracking their menstrual cycles, odorant testing, and completing daily logs of olfactory and psychosocial information. The explicit purpose of the study was presented in detail as a study of the effects of the menstrual cycle on changes in olfactory sensitivity during the context of everyday life (e.g., Doty, Snyder, Huggins, & Lowry, 1981). They were told that these odors would be mild, at or below the level of conscious detection. During the consent process, they were given a list of 70 natural compounds that they might receive. In fact, all participants were given cotton pads without a specific odorant, although the pads themselves did have a mild odor.

Each participant was taught to fill out a prospective daily logbook in which she recorded the daily menstrual cycle data described above. Throughout the study, she also recorded psychosocial and behavioral data about her activities that day. To ensure compliance and maintain the blinding procedure, we asked participants to come to the laboratory twice per week. During these visits, the experimenter ensured that they were collecting data in the appropriate way and gave them additional "odor" pads. At the end of the study, participants completed an out-take interview and gave additional information on sexual orientation and current romantic partner status.

Measurement of Sexual Activity

Participants were asked to record in their daily logbook occurrence of a wide variety of physical activities, physical symptoms, and illnesses. In the midst of this extensive form was an item to check if they had engaged in sexual activity that day. Sexual activity was defined as including both activity with another person and masturbating alone. When activity was with a partner, participants also indicated who initiated the activity: oneself, one's partner, or both. No subject detected an experimental focus on sexual activity or motivation.

STUDY 1

In Study 1, we asked whether precisely defining the phases of the menstrual cycle with reference to the onset of the preovulatory LH surge would reveal a periovulatory or premenstrual increase in sexual activity, particularly when initiated by the woman.

Methods

To answer this question, 19 women between the ages of 20 and 32 years provided daily sex and menstrual cycle data for up to five menstrual cycles, with a total of 57 cycles contributed from the 19 women. A good estimate of the change in each woman's behavior across menstrual cycle phase was obtained by collecting data from multiple cycles and summarized for each woman as the percent of cycles with sexual activity on a given day. This also addressed the issue of nonindependence arising from multiple cycles from the same women. Thirteen study participants identified themselves as single, one lived with her partner, and five were married. All women reported sexual activity during at least one phase of the menstrual cycle.