Article summary with Do Hormones Influence Women's Sex? Sexual Activity over the Menstrual Cycle by Caruso a.o. - 2014

What was studied for this article?

Female mammals, such as many other animals, experience increased sexual activity during estrus. However, women do not exhibit a clear heat period and their sexual activity is not significantly influenced by the different phases of the menstrual cycle. Studies have found low correlations between sex hormones and subjective/objective measures of sexual arousal in women. Some research suggests that sexual desire may increase around the presumed ovulation phase or the follicular phase of the menstrual cycle. However, hormonal influences on female sexuality are challenging to demonstrate due to various factors, including constant male sexual interest, contraceptive use, and methodological difficulties in assessing cycle phases. Other influences, including psychosocial factors, may play a significant role in female sexual experience.

The study described in this article aimed to investigate the correlation between sexual behavior and hormonal status in women with ovulation. The study involved a group of heterosexual women who were invited to participate and met specific criteria, excluding pregnant or postpartum women, those taking hormone therapy or contraceptives, and those with certain medical conditions. The study aimed to understand the relationship between hormones and sexual behavior in women.

How did the study go?

The study began with a screening phase in which women with regular menstrual cycles and ovulation were included. Sonography was used to confirm ovulation by detecting the dominant follicle. Interviews were conducted to collect information on sexual history and exclude women with sexual dysfunction. The Female Sexual Function Index (FSFI) and Female Sexual Distress Scale (FSDS) were used to assess sexual function and distress.

In the study phase, participants were given diary cards to report their daily sexual activity throughout the menstrual cycle. Women were instructed to complete the diary cards daily, and on average, they returned 31.5 daily reports. Blood samples were taken at specific times during the menstrual cycle to measure hormone levels, including estradiol, progesterone, total testosterone, and sex hormone-binding globulin.

Statistical analysis was performed to determine if there were changes in the frequency of sexual activity related to the phase of the menstrual cycle. The analysis included factors such as women with a partner vs. singles. The Bonferroni method was used for multiple comparisons. Spearman's correlation coefficient was used to correlate sexual activity with hormone levels. Multivariate analysis was conducted to examine if factors like age, body mass index, age of menarche, parity, or smoking influenced sexual activity.

The statistical analysis was performed using specific software packages for biostatistics and regression analysis.

What were the results of the study?

Among the women who completed the study, 925 had a sexual partner and 255 did not. The two groups of women did not differ significantly in demographic and menstrual cycle characteristics or lifestyle factors. Women with a partner had higher average age, body mass index (BMI), and age at menarche compared to women without a partner. Single women smoked more than those with a partner.

The researchers measured hormone levels during different phases of the menstrual cycle and found that they followed expected patterns. Estradiol, total testosterone, free androgen index (FAI), and sex hormone-binding globulin (SHBG) levels increased from the follicular to the periovular phase and then decreased until menses. Progesterone levels increased from the follicular to the luteal phase.

The researchers also assessed sexual behavior using the Female Sexual Function Index (FSFI). They found that women with a partner had higher scores for arousal but lower scores for orgasm compared to women without a partner. Women with a partner reported higher frequency of desire, arousal, and maintaining lubrication compared to singles. However, singles had higher levels of arousal and orgasm frequency and lower difficulty in achieving orgasm compared to women with a partner. Satisfaction scores were not comparable due to lack of response from women without a partner.

The study also examined the initiation of sexual activity by women and their partners throughout the week and during different phases of the menstrual cycle. Women with a partner showed an increase in sexual activity from the follicular to the periovular phase, followed by a decrease during the luteal phase and another increase during menses. Women without a partner had the highest sexual activity during the periovular phase and the lowest during menses. Women with a partner had overall higher sexual activity compared to singles, except during the periovular phase where singles had higher activity.

The researchers observed that women without a partner masturbated more during the periovular phase compared to women with a partner. They also found that 16% of women with a partner masturbated during intercourse to facilitate orgasm.

In terms of hormonal correlations with sexual activity, there were positive correlations between sexual activity and total testosterone (TT) and free testosterone (FT) levels in women with a partner during the follicular and luteal phases. In women without a partner, there were positive correlations between sexual activity and TT and FT levels during the periovular and luteal phases.

Overall, the study found that sexual activity and hormone levels varied throughout the menstrual cycle and differed between women with and without a sexual partner. The findings suggest that hormonal fluctuations may influence sexual behavior in women, and the presence of a partner may also impact sexual activity.