Sexual function is an important component of women's lives. It has been reported that low sexual function adversely affects women's quality of life and interpersonal relationships.1 Sexual function in women is determined by multiple aspects, including biological, medical, and psychological factors.2 It is associated with sociodemographic, and also behavioral characteristics of women, such as degree of education and physical activity. One's relationship with a partner and the length of marriage have a great impact on sexual function.3,4
Sexual function declines with ageing and throughout the menopausal transition in middle-aged women.5,6 It is further affected by reduced levels of estrogen and androgen during menopausal transition and ageing, respectively.7 The decrease in levels of estrogen and androgen may influence sexual desire, and this decrease is also associated with vaginal atrophy.7,8 Vaginal atrophy may lead to unpleasant sexual experiences due to vaginal dryness and dyspareunia in middle-aged women, further adding to a disruption in the intimacy-based sexual response cycle.9
Attitude toward sex has an important role in sexual function.3 China is a nation with a long history of conservatism, and the Chinese, especially females, are reluctant to discuss sexual topics.10 A few studies using the Diagnostic and Statistical Manual of Mental Disorders and self-administered questionnaires have evaluated sexual function and sexuality among middle-aged women in Hong Kong, China.11,12 The Female Sexual Function Index (FSFI) is a broadly used and highly reliable instrument for assessing sexual function, and was recently validated for use among Chinese women.13 However, limited data exist on sexual function among Chinese women, using FSFI criteria. We conducted a cross-sectional study to compare sexual activity and function among middle-aged Chinese women of different age groups, aged 45 to 50, 51 to 55, and 56 to 60 years. We also evaluated the association between sexual function and vaginal maturation status among these women.
Middle-aged women who visited our gynecology outpatient clinic at the First Affiliated Hospital of Dalian Medical University (DMU) for common gynecological disorders were recruited for participation in the study. All the women were married and had completed at least primary education. They all had an intact uterus and ovaries. None of the women had undergone hormone therapy. The exclusion criteria were the presence of cardiac, hepatic, and renal disorders; a history or presence of malignancy; cognitive dysfunction; and psychiatric disorders. In all, 208 women aged 45 to 60 years were requested to participate in the survey; 139 of these agreed and were screened over a 3-month period. Nineteen women were excluded for not satisfying the inclusion criteria. Four women had a history of hysterectomy/oophorectomy. Seven women were not sexually active due to being divorced/widowed. Eight women did not complete the questionnaires. Ultimately, 120 women (mean age 53.1 ± 4.7 years) participated (Fig. 1). All women gave written informed consent before participation.
A cross-sectional survey was administered at the gynecology outpatient clinic of the First Affiliated Hospital of DMU. Participants were assigned to three age groups, namely, 45 to 50 (youngest group, n = 40), 51 to 55 (intermediate group, n = 41), and 56 to 60 years old (eldest group, n = 39). Two 63-year-old women were included in the eldest group (Fig. 1). All participants were interviewed by the same investigator. A general questionnaire collecting demographic data and information regarding body weight/height and sexual activities during the past month was completed. The Chinese version of the FSFI13 was used to assess women's sexual function. Vaginal smears and pH values were obtained to evaluate vaginal maturation status. The study was approved by the ethical committee of the First Affiliated Hospital of DMU.
The following demographic data were obtained: age; educational level (junior high school, senior high school, college, or above); work status (employed or retired/housewife); place of residency (rural/urban), menstrual status according to the stages of the Reproductive Ageing Workshop, defined as premenstrual (regular menstrual cycle), perimenopausal (variable cycle length), or postmenopausal (absence of menses over the past 12 months)14; physical activity, with regular exercise defined as that occurring one to two times per week (yes/no); hypertension, with displayed blood pressure readings of 140/90 mm Hg or being already on medication (yes/no); parity and delivery mode; and body mass index (BMI), classified as low (<18.5), normal (18.5 to 24.9), and obese (>25), according to the criteria for Asian women.15 Length of marriage and husband health status were also recorded.
Sexual activities during the past month
Information was also obtained on participants’ sexual activities during the previous month. (1) Sexual frequency, which was classified as 1 to 2 sessions/wk, 1 to 2 sessions/mo, and <12 sessions/yr, was reported by participants; (2) sexual distress, referring to negative feelings and anxiety regarding sexual activity, was then recorded (yes/no), and so was (3) verbal communication about sexual matters with husbands (yes/no).
Sexual function assessment
The FSFI was used to evaluate sexual function. It consists of 19 questions, making up 6 domains, namely, sexual desire, arousal, lubrication, orgasm, satisfaction, and dyspareunia. Each item yields a score ranging from 0 to 5. Scores obtained for each item are then summed up within each domain and then multiplied by a constant factor to yield individual domain scores. The total FSFI score is the sum of scores obtained for each domain, and ranges from 2 to 36, with a higher score associated with a lesser degree of sexual dysfunction.
Vaginal maturation status
Vaginal maturation status, serving as an objective means of evaluating estrogen secretion, was assessed through the Vaginal Maturation Index (VMI) and the vaginal pH value.
Vaginal smears were obtained with gentle scrapes in the upper third of the vagina, using a cotton swab, and placed evenly on the slides. The slides were fixed in 95% alcohol and stained. VMI was determined through measurement of the cell types present on the slides. The superficial/intermediate/parabasal cells in each slide were evaluated by two investigators blinded for the groups, and the percentage of superficial cells was calculated. The means of the two evaluations were used for statistical analysis. A proportion of superficial cells exceeding 60%, coupled with no presence of parabasal cells in a slide, indicating mature epithelium, was classified as a high degree of estrogen effect. A proportion of superficial cells less than 20% and the presence of more parabasal cells, indicating immature epithelium, were classified as a mild degree of estrogen effect. Superficial cells of between 20% and 60%, and the presence of more intermediate cells were classified as a moderate degree of estrogen effect.16
Vaginal pH value was checked using a dipstick and compared with the standard colorimetric card.
The quantitative values were expressed as mean ± standard deviation or medians and quartile ranges based on distribution. Analysis of variance (ANOVA) followed by the least significant difference t test was used to analyze differences between the groups. A repeated-measures analysis of covariance (ANCOVA) and factorial ANOVA were used to adjust for the confounding effects and analyze the interaction effect of age and menstrual status, respectively. Qualitative data were presented in the form of percentages. The chi-square test, followed by pair-wise comparisons, was used to compare differences between the three groups. Spearman's correlation test was used to analyze the correlations between the FSFI scores and vaginal maturation status (VMI and pH value). A P value of <0.05 was considered to be statistically significant.
The sociodemographic characteristics of the 120 women in our three different age groups are shown in Table 1. As expected, there was a statistically significant difference with regard to age between the three groups of women. The groups were comparable with regard to education levels, place of residency, parity/delivery mode, the proportion of women with a history of hypertension, BMI, and physical activity levels. However, the menstrual status of the women in the three groups differed significantly (P < 0.001). Moreover, the ratio of women who were menopausal increased with age, from 17.5% in the youngest group, 65.9% in the intermediate group, to 100% in the eldest group. Work status also differed significantly (P < 0.001); the proportion of retired women increased with age, from 25% in the youngest group, 53.7% in the intermediate group, to 92.3% in the eldest group. Approximately 10% to 12% of women in each group were hypertensive. The husband-related factors (ie, age and health status, and the length of marriage) were comparable between the groups (data not shown).
Information regarding the sexual activity of the women in the three age groups is shown in Table 2. The women in the youngest and intermediate groups were much more sexually active, reporting a higher frequency of sexual activity (1-2 sessions per week or month) than did those in the eldest group (P < 0.001). Furthermore, low sexual activity frequency (<12 sessions per year) was more prevalent among the women in the eldest group than among those in the youngest and intermediate groups (P = 0.002, respectively). A Bonferroni correction of this P value gave P = 0.017, representing a significant difference. Though a minority of women reported sexual distress, at 2.6%, the women in the eldest group were least likely to report the issue (P = 0.086). More than 50% of the women in each group did not verbally communicate about sexual matters with husbands.
The FSFI scores obtained by the women in the three groups are documented in Table 3. The total mean scores of the FSFI differed significantly among the three groups (P < 0.001). Further analysis revealed that the eldest group obtained a lower score than that of the youngest and intermediate groups (P < 0.01 and <0.05, respectively). There were significant differences between the three age groups (P < 0.01, 0.001, and 0.01, respectively) with regard to the mean scores on sexual desire, lubrication, and pain. Further analysis revealed that the domain score of sexual desire was significantly lower in the eldest group than in the youngest group (P < 0.01). The mean score on sexual lubrication was lower in the eldest group than in both the youngest and intermediate groups (P < 0.01 and <0.05, respectively). The mean score on sexual pain was lower both in the intermediate and eldest groups than in the youngest group (P < 0.05 and <0.01, respectively). Mean scores on arousal and satisfaction tended to differ across the three groups (P = 0.05 and 0.08, respectively). Further post hoc analyses showed that the tendencies were attributable to significant differences between the eldest and youngest groups (P < 0.05). There was no significant difference between the three groups in the domain score on sexual orgasm. In addition, the results did not change after adjusted ANCOVA for the correction of work status, which differed across the groups, in sexual function (ie, for the total FSFI score, the domain scores on sexual desire, lubrication, and pain among the three groups; P < 0.05). Menstrual status differed across the groups, and together with age, had an interaction effect on sexual function. Indeed, the interaction effect of age group and menstrual status was demonstrated through factorial ANOVA (P < 0.05). On its own, age group had a significant effect on sexual function (P < 0.05), whereas menstrual status alone had an inclination in this regard (P = 0.097).
Among the 120 eligible women, 78 had randomly taken vaginal smears for evaluating VMI and measuring pH value. However, vaginal smears in 8 of the 78 women were excluded due to uneven distribution of the exfoliated cells, which could not be evaluated under the microscope. Therefore, 70 women were analyzed for VMI, 26 in the youngest, 23 in intermediate, and 21 in the eldest groups (Fig. 2). VMI, classified with a mild to moderate and high degree of estrogen effect (Fig. 2A, B, and C), significantly differed across the three groups (P < 0.001). A high degree of estrogen effect was exhibited in 80.8% of the women, whereas there was a mild degree of estrogen effect in 7.7% of the women in the youngest group. In contrast, a high degree of estrogen effect was present in 28.6% of the women; a mild degree was exhibited in 38.1% of the women in the eldest group (P = 0.001; Fig. 2D). A Bonferroni correction of the P value yielded 0.017. The mean vaginal pH values were 5.56 ± 0.85, 5.80 ± 0.87, and 6.31 ± 0.84 in the youngest, intermediate, and eldest groups, respectively. A significant difference was revealed between the youngest and eldest groups (P < 0.01).
Vaginal Maturation Index positively correlated with the total FSFI score, and also with individual domain scores of sexual desire and lubrication (r = 0.26, 0.25, 0.34; P < 0.05, 0.05, 0.01). pH value was inversely associated with the total FSFI score (Fig. 3), and also with individual domain scores on sexual desire and lubrication (r = −0.47, −0.37, −0.38; P < 0.01). Moreover, pH value was related to the other individual domain scores, that is, sexual arousal, satisfaction, orgasm, of sexual function, especially to vaginal pain (r = −0.44, P < 0.01).
This was a cross-sectional study comparing the sexual activity and function of different age groups of middle-aged Chinese women. We found that Chinese women at age 56 to 60 years experienced lower sexual frequency and less sexual distress than did women aged 45 to 55 years, as discussed below. Sexual function among the 56 to 60-year-olds was also significantly lower than that among women aged 45 to 55 years. Moreover, sexual desire was lower among 56 to 60-year-olds, compared with 45 to 55-year-olds. Nevertheless, vaginal discomfort during sexual intercourse became more prevalent with age. In addition, sexual function was significantly associated with participants’ vaginal maturation status.
Sexual function is influenced and classified by sociodemographic, physical, and psychological factors.17 Some of the factors reported to be significantly associated with sexual function are education level, chronic medical disease, BMI, length of marriage/relationship, and a partner's health status.4,18 In the present study, a small proportion of women in each group had hypertension; the proportion did not differ across the three groups. The factors associated with sexual function, namely, education level, parity/delivery mode, BMI, and physical activity level, among others, were comparable across the three groups. This was also true for the length of marriage and health statuses of participants’ husbands.
A previous study indicated that more frequent sexual activity was associated with a younger age.19 It has been reported that Chinese women have fewer intimate encounters and less coitus upon reaching menopause.12 In the present study, the women in the eldest group, who were all postmenopausal, reported less frequent sexual intercourse than did those in the youngest and intermediate groups, who were mainly premenopausal or perimenopausal. The result is consistent with the previous report that more than 50% of postmenopausal women have fewer than 12 sessions of coitus within a year.12 The frequency of sexual activity may vary according to race and ethnicity. In a large study on middle-aged and older women, Asian women tended to report less frequent sexual activity than did White women.20 In another large cohort study of women aged 42 to 52 years, Chinese and Japanese women had less frequent sexual intercourse than did African-American and White women.3
Sexual distress is characterized by negative feelings and anxiety about one's sexuality or sexual activity. Berra et al21 evaluated sexual distress using a female sexual distress scale, and revealed that impairment of sexual function was less distressful for postmenopausal (36.2%) than for premenopausal women (64.5%). In a 10-year follow-up study on middle-aged women, wherein a similar scale was used, a minority (17%) of postmenopausal women were significantly distressed about low sexual function.22 We assessed sexual distress using self-administered questionnaires. The result is consistent with Berra et al's finding that declined sexual function was less distressful for postmenopausal than for premenopausal/perimenopausal women. However, the percentage of women who reported sexual distress was low (2.6% among women in the eldest group), compared with those in previous studies.21,22 Nevertheless, our result in this regard ought to be confirmed through a study using a female sexual distress scale to assess sexual distress. Likewise, the rate of verbal communication among women in each age group was low. Pan et al also reported that a minority of Chinese women share their feelings regarding sex with their partners.23
Low rates of sexual frequency, distress, and verbal communication among middle-aged women in our study could be attributable to traditional Chinese culture and attitudes towards sex. Among Asian women, sexuality is more linked to procreation.24 Okazaki24 demonstrated that African-Asian women share Asian cultural characteristics such as the primacy of the family, the appropriation of sexuality only within the context of marriage, and sexual restraint and modesty. Indeed, as noted previously, China is a nation with a long history of conservatism and the Chinese, especially females, are reluctant to discuss sexual topics.10
The FSFI is a broadly used and highly reliable instrument for assessing female sexual function.13 Few studies have evaluated sexual function in middle-aged women using this instrument.6,25 In our study, there was a significant reduction in the total FSFI score among women in the eldest group, compared with those in the youngest and intermediate groups. The finding probably indicates a significant decline in sexual function in women after menopause. A similar pattern was evident in the domain of FSFI for sexual desire, arousal, and satisfaction. The results are consistent with Nappi et al's6 findings that the overall FSFI score varies with stage of menopause, with the total FSFI score being less in early postmenopausal women than in perimenopausal women, as does the domain score of FSFI for sexual desire, arousal, satisfaction, and orgasm. However, there was a discrepancy in the aspect of sexual orgasm, in which we did not find a significant decline in the score. In the literature, data supporting the association of menopause with low desire and arousal, but problems with orgasm, are not consistent.26 A major limitation of the FSFI questionnaire has been reported.27 This questionnaire is heavily reliant on vaginal intercourse, and records activities relating to the previous month only. In our study, a minority of women reported no sexual intercourse during the previous month. Sexual activity and function were evaluated according to last intercourse.
In the present study, we observed a gradual reduction in the domain score of FSFI for vaginal lubrication and pain among the women according to age. Moreover, multiple analyses revealed lower scores among the women in not only the eldest group, but also among those in the intermediate group, compared with the youngest group. The result may suggest that vaginal discomfort during sexual intercourse becomes more serious with age (ie, from 45 to 60 years old). Indeed, an age-related reduction in lubrication and sex-related pain has been documented.18,21 Lo and Kok12 reported that vaginal lubrication is the most common cause of sexual dysfunction and predominantly affects middle-aged Chinese women.
The genital tract is the target organ of sex hormones. VMI and vaginal pH are objective measures, representing the estrogen effect on vaginal epithelia.28 Low estrogen levels are associated with vaginal atrophy and a decrease in the glycogen concentration that hinders the production of lactic acid by lactobacillus organisms.8 We found a significant decline in VMI and a rise in the pH value among middle-aged women with age, indicating a reduced degree of estrogen effect on vaginal epithelia. However, a high estrogen effect was present among few women in the eldest group. Few of these confirmed dietary intake of health products, which may have an effect on VMI. Vaginal pH value may be a better measure than VMI for the clinical evaluation of the vaginal ecosystem.8 Indeed, vaginal pH, but not VMI, was significantly associated with both vaginal lubrication and pain in our study.
Both a central permissive role of estrogen in awareness and receptivity and an initiating role of androgen in desire are evident in women.29 Estrogen preserves vaginal responsivity and helps to alleviate dyspareunia, whereas androgen directly modulates vaginal and clitoral physiology, by influencing the muscular tone of both erectile tissue and vaginal walls, and contributing to sexual desire/arousal and vaginal lubrication.29,30 Both serum estradiol and free testosterone levels decrease in women undergoing natural menopausal transition6; these changes are associated with reduced sexual desire and vaginal maturation status.7,31 Ageing per se further contributes to the detrimental effect of menopausal hormonal changes on the central and peripheral neural circuits involved in the sexual activity of middle-aged women.6 Therefore, the decline in sexual function among middle-aged women in our study is probably attributable to both hormonal changes and ageing. Indeed, we found a significant interaction effect of menstrual status and age on sexual function.
A feature of this study lies with the sample studied, in that middle-aged Chinese women of different age groups were compared using the FSFI, and the correlation between their sexual function and vaginal maturation status determined. The findings suggest that sexual desire may be reduced after menopause, and that vaginal dryness and dyspareunia may become more prevalent along with menopausal transition. Therefore, vaginal lubrication may continuously affect the sexual life of middle-aged women.3 However, this was a study conducted on a small sample size, using cross-sectional data. The findings may serve as a basis to plan a larger and prospective study. The study has important limitations. It was a cross-sectional study, participants were women attending gynecology check-ups for common disorders, and the sample size was small. Furthermore, there were few premenopausal participants. Thus, the findings cannot be generalized to the wider population. A large, prospective study in community-dwelling middle-aged women is needed to verify our findings.
Among middle-aged Chinese women, sexual desire is lower among those aged 56 to 60 years, compared with those aged 45 to 55 years. Moreover, vaginal dryness and dyspareunia among women become more prevalent with age. Importantly, sexual function is associated with vaginal maturation status in women at midlife.
Authors thank the women who volunteered to participate in the study.
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