The present study aimed to determine the socio-demographic factors associated with LSD and HSDD. According to existing research, FSIAD can be best described as a lack of sexual thoughts or fantasies, absence of responsive desire, and diminished or absent feelings of sexual desire or interest. Therefore, FSIAD is linked with an abnormally low or absent sexual drive or lack of incentive to become sexually aroused [21, 22].
Women with HSDD suffer from emotional and psychological problems due to this disorder. The majority of them complain about feeling less feminine, with a major body-image impact, feelings of concern, unhappiness, frustration, anger and even shame as well as being concerned because they were “letting their partner down” .
When LSD is accompanied by personal distress, it is clinically known as HSDD . Therefore, it seems that HSDD is a more severe form of LSD and it may require more extensive clinical therapeutic interventions, while LSD can probably be improved with counselling interventions. Therefore, preventive measures are necessary to avoid progression of LSD to HSDD.
Among the factors explored, the socio-demographic variables associated with LSD were age, length of marriage, age at first intercourse, alcohol consumption, level of physical activity, BMI, and level of satisfaction with income. Whereas satisfaction with income, years spent in marriage, and age at first intercourse were the only variables associated with HSDD.
Our findings support the significant role of ageing in the occurrence of LSD (not HSDD). Results of the logistic regression indicated that by controlling other demographic variables, risk of LSD increased with advancing age in women, but does not have any significant association with HSDD. Such a correlation was also observed in the study by Hayes et al.  performed in four European countries (i.e., UK, Germany, France, and Italy) and the USA to examine the relationship between age and HSDD. Hayes's findings showed that the risk of LSD tends to increase with advancing age from 11%-53% in European women and 22%-32% in American women, but the prevalence of HSDD did not change significantly with advancing age. In other words, the results of that study, similar to our findings, suggested that although increasing age promotes the risk of LSD, the level of distress does not increase with age. Thus, it can be concluded that advancing age does not lead to an increased risk of HSDD, resulting in a relatively constant prevalence of HSDD over time. This finding was also noted in a literature review study on female sexual dysfunction highlighting HSDD . A more recent study (2017) also showed that although age was identified as one of the factors contributing to LSD, it was not reported among factors associated with sexually-related personal distress and HSDD . In a qualitative study in Iran , most of the participants were reluctant to have sex even if they had to be sexually active for the sake of their partners’ satisfaction. Some women considered sexual relationships specific to the period of younger age. In other words, asexuality was a culturally accepted practice for older Iranian women. This is why most of the middle-aged women with LSD in this current study did not report sexually-related distress.
Despite the above findings, some studies suggest that there is no relationship between sexual desire and interest and age [27, 28]. Some studies have even shown that sexual desire increases with age . The difference in results can be attributed to the differences in the statistical populations, sample sizes, participants’ age range, and the tools used to assess HSDD. Previous research in this area did not consider sexual distress as an essential criterion for defining HSDD. It seems that women’s age might be one of those important factors that should be taken into consideration when screening for sexual desire problems.
Another factor related to LSD (not HSDD) in this study was BMI. The present study indicated that by controlling other variables, increased BMI elevated the risk of LSD (the odds ratio for LSD in women with BMI ≥ 30 was 1.8 times greater than those with BMI > 25), but it did not result in an increased risk of HSDD. Studies also suggest that there are inconsistent findings on the association between sexual desire and BMI, and they found no difference in the association between LSD and BMI and HSDD and BMI. The results of a study conducted in Turkey showed that BMI was not a risk factor for sexual dysfunction, and no difference was found between healthy weight and obese individuals in terms of sexual desire . Esposito in the study of obesity and sexual dysfunction pointed out that among the sexual activity parameters, sexual desire and pain were not related to BMI, while an inverse relationship was found between weight and the other sexual domains .Similarly, Mozaffari et al. in a case-control study of body weight and female sexual dysfunction in Iran reported the same findings . Bajos also reported no difference in sexual dysfunction (i.e., lack of libido, sexual arousal, and sexual pain) between obese and normal-weight women. The relationship between obesity and sexual function is complex. Therefore, it is necessary to address the direct effects of obesity, pathophysiologic comorbidities and the obesity-related psychological factors to prevent LSD and HSDD in women. This inconsistency in findings might be due to the fact that these studies were conducted in different socio-cultural contexts using different tools and sample sizes.
Regarding the length of marriage, the present study found that by adjusting other variables, as the length of time spent in marriage increased, the risk of LSD and HSDD also elevated. Therefore, after 10 years or more of marriage, the possibility of having LSD and HSDD in women would be 2.4 and 3.2 times higher than women who have been married for less than two years. Likewise, the findings of the present study, many other studies have confirmed the inverse relationship between the length of marriage and sexual desire problems. The results of another study conducted among 356 women aged 20-70 years indicated that women who had been in relationships lasting for 20-29 years experienced higher levels of disaffection compared to women who had been in a relationship for less than five years . Pfaus's review also signified that after controlling for the age variable, women's sexual desire had a significant inverse relationship with marriage duration . Kim (2013) also reported that women with HSDD who had been in long-term relationships tended to have lower scores for sexual desire . Therefore, these findings show the necessity of adopting preventive interventions to promote couples′ sexual health throughout their married life.
In this nationally representative sample, age at first intercourse was also identified as a factor associated with both LSD and HSDD, such that having the first sexual intercourse at a very young age can be considered a risk factor for LSD and HSDD. According to the results of Abdo et al.  in Brazil, women whose age at first intercourse was more than or equal to 21 were 1.5 times more likely to experience HSDD compared to women whose first intercourse was between 9 and 17 years of age. On the other hand, in a study by Safarinejad et al.  in Iran, it was found that a younger age at marriage significantly contributed to sexual dysfunction. The discrepant findings might be due to the different socio-cultural factors in the design of those research studies. In the Western world, women usually experience their first intercourse at a very young age, but in the Eastern world and most of the Muslim countries including Iran, any extramarital sexual relationship is not accepted socially, culturally and legally.
Controlling of the other socio-demographic variables revealed that increased satisfaction with monthly income decreased the possibility of having LSD and HSDD. Therefore, satisfaction with income acts as a protective factor against developing HSDD. It appears that satisfaction with income level lowers the risk of LSD and HSDD through decreasing tensions and stress in women’s lives. This finding is in line with the results obtained by Ghanbarzadeh et al. , which highlighted the role of financial problems as a major risk factor for developing LSD in women. Results obtained from another study also revealed that the emergence of sexual desire problems in the face of financial dependency is highly probable . In a study conducted among 1000 married women aged 16-49 years in Egypt, it was demonstrated that most of the participants believed that LSD is associated with socio-economic conditions such as economic stressors and low income . In contrast, a study conducted in China showed that by controlling variables such as age, level of education, and age at marriage, increased average monthly income in women resulted in an improved sexual relationship . It can only be justified by the fact that financial dependence on the spouse causes false interest in couples to have intercourse.
It is noteworthy that despite the non-significant P-value for the level of education variable (secondary category), a high odds ratio was observed for this variable (OR:3; 95% CI:0.9-9.6). This result could be due to the limited number of cases with HSDD in the primary-illiterate category (4 cases). Therefore, the level of education should not be disregarded while assessing and managing HSDD.
The strengths of this current study include its sample size of 1000 married women of reproductive age. Also, since sexually related distress is an essential factor in identifying HSDD, in this study SIDI-F and FSDS-R were used for the diagnosis of HSDD. However, this study had some limitations that need to be addressed. As we know, the etiology of LSD or HSDD is complex and multifactorial. Thus, we could not consider all the factors affecting sexual desire such as personal circumstances (e.g., psychosexual, physical, and biological factors) and relational conditions . It is worth noting that the sexual response cycle is a concept of psychophysiological alteration, and any attempt to stage the female sex response, although useful, is artificial . Also, the other possible comorbidities such as having difficulty in getting aroused or lubricated, having difficulty in reaching orgasm, feeling pain during or after intercourse, and experiencing vaginal dryness should be addressed while assessing female sexual desire problems, which were not measured in the study.
Likewise, Kim et al.  reported a significant association between sexual desire and other domains of female sexual function, indicating the need to examine other sexual disorders in the evaluation of sexual desire because components of women’s sex response often overlap with each other, such that sexual desire interacts with and partially overlaps with mental arousal . Basson  also proposed that the onset of responsive desire is accompanied by sexual arousal to some extent, which shows that sexual desire and sexual arousal are probably a unitary concept, as in DSM-5 they are categorized under FSIAD .
Moreover, in this study, the role of the emotional connection between the research participants and their husbands which is an essential aspect in determining female sexual function was not measured. It seems questions such as the stability of the relationship, satisfaction and happiness as well as the sexual and general health of the partner can be used to identify people with LSD and subsequent sexual distress.
In line with this statement, many studies have shown that male partners’ sexual dysfunctions, especially erectile dysfunction and premature ejaculation harm female sexual desire [42-45]. Therefore, it is important to note that clinicians should evaluate the sexual function of both partners, which encompasses several dimensions and needs an interdisciplinary approach. Therefore, further studies need to be done to gain a deeper understanding of socio-cultural contexts of women’s sexual and reproductive health.