Women's Sexual Function and Dysfunction. Irwin Goldstein MD

Oral contraceptives and sexuality

Anne R Davis, Paula M Castano

Introduction

In women, sexuality and contraception are tightly linked. In the USA, the average age of initiating sexual activity is 17.8 years,and the average age of menopause is 51.4 years.2 A typical fertile and sexually active woman with two children might spend only about 3 years seeking pregnancy and being pregnant. Therefore, she would use contraception for about 29 years of her life.

In the USA, oral contraceptives are the most widely used reversible contraceptive method. In 1995, current oral contraceptive use was reported by 27% of all contracepting women aged 15-44 years, and 45% of those aged 15-30 years.1 Stated another way, about 10 000 000 US women described themselves as current oral contraceptive users. Rates of use in European countries are even higher.

Several characteristics make oral contraceptives well suited for use by most women. First, oral contraceptives are very effective and completely reversible. Perfect oral contraceptive use is associated with annual pregnancy rates of less than 1% and typical oral contraceptive use with rates of approximately 7%. Second, oral contraceptives have a well-established safety profile. Third, oral contraceptive use is associated with health benefits, including decreased risk of ovarian cancer, uterine cancer, benign ovarian cysts, endometriosis, and pelvic inflammatory disease. Oral contraceptive use is also associated with desirable changes in the menstrual cycle, including improved cycle control, decreased menstrual cramps, decreased volume of menstrual blood, and fewer days of menstrual bleeding. Oral contraceptives are also an effective treatment for acne vulgaris and even hirsutism.

Most research has focused on the safety and efficacy of oral contraceptives. Little research has examined the effects of oral contraceptive use on sexuality. Reducing the fear of unwanted pregnancy is one potential positive effect. In a recent focus group study, women reported that fear of pregnancy had a very negative impact on sexual arousal, especially when the partner did not share this concern.3 Oral contraceptive-mediated improvements of painful gynecologic conditions such as endometriosis, dysmenorrhea (painful menstrual cramps), and ovarian cysts may also improve sexual functioning. Changes in bleeding patterns during oral contraceptive use could also improve sexual functioning. Many couples avoid intercourse and other sexual behaviors during vaginal bleeding or spotting due to cultural custom, fear of infection, or hygienic reasons.4,5 By decreasing the days and amount of menstrual bleeding, oral contraceptive use could increase the times when couples are willing to engage in sexual behaviors. Finally, oral contraceptives are approved by the US Food and Drug Administration for the treatment of acne vulgaris. Improved appearance associated with decreased acne could indirectly benefit sexual functioning. In one study, an improvement in acne was associated with decreased embarrassment and social inhibition.6

Oral contraceptives could also exert negative effects on sexual function. Early literature invoked psychologic mechanisms such as women feeling less interested in sex because of not being fertile, or “missing the element of risk” while on contraceptives.7 Some authors hypothesized that oral contraceptives indirectly, affect sexual functioning by causing negative changes in mood or weight. Such negative changes are often accepted as known side effects of oral contraceptives. However, little well- conducted research, including appropriate control groups, has examined mood or weight effects in detail. Data from a few large, placebo-controlled oral contraceptive studies suggest that large effects on mood or weight attributable to oral contraceptives are unlikely, since subjects on oral contraceptives and placebos reported similar rates of mood changes and weight gain.8,9 However, these studies were not designed to measure effects on mood or weight and therefore did not use appropriate psychometric or physical measurement techniques.

The impact of oral contraceptives on sexual desire, or libido, has received more study than any other possible effect of oral contraceptives on women’s sexual functioning. Physiologic changes associated with oral contraceptive use make an oral contraceptive-mediated effect on libido biologically plausible. Combination oral contraceptive pills consist most commonly of 21 days of tablets that contain ethinyl estradiol and a synthetic, orally active progestin, followed by 7 days of inert or placebo tablets. Their main mechanism of contraceptive action is prevention of ovulation through inhibition of gonadotropin release from the pituitary, an effect which interferes with the normal cascade of events that leads to ovulation.

In addition to these changes, oral contraceptive use also causes an important reduction in androgens via several mechanisms10 (see Chapters 5.5 and 6.3 in this volume). First, the estrogen in oral contraceptives causes an increase in hepatic production of serum hormone-binding globulin, one of the two main proteins binding testosterone in the serum. Due to increases in sex hormone-binding globulin, levels of free testosterone decrease by about 50% during oral contraceptive use. Second, oral contraceptives decrease production of androgens by the ovaries and adrenal glands. Third, oral contraceptives inhibit the enzyme 5-alpha reductase, which converts testosterone into dihydrotestosterone, the form that binds to cellular receptors.11 The decreased androgenic environment associated with oral contraceptive use is therapeutically useful; both acne and hirsuitism improve during oral contraceptive use.

The reduced androgen environment caused by oral contraceptives is often cited as the mechanism by which oral contraceptives decrease sexual interest in women. In order to assess evidence related to whether or not oral contraceptives affect libido in women, we conducted a search of the medical literature from 1966 until 2004.

Retrospective, uncontrolled studies

In these retrospective uncontrolled studies, women compared their libido before and after initiation of oral contraceptives. Table 7.6.1 summarizes results from these studies. Changes in libido attributed to oral contraceptives were highly variable; with women reporting large increases in libido to modest decreases. Several factors could account for these results. Studies conducted in the 1960s found larger increases in libido than later studies. Large increases in libido in the early studies may indicate that women had a new opportunity to be sexually active without the fear of pregnancy. Variability in measurement may also account for inconsistent results. Women were directly questioned about libido in some studies, while in others investigators relied on spontaneous reports. In studies where the questions were explicitly stated, more women reported increases than decreases in libido.71314

In summary, these retrospective studies found that most women experienced an improvement or no change in libido during oral contraceptive use, with a minority reporting negative effects. However, numerous methodological limitations make conclusions from these data difficult. In a retrospective study, participant reports may not be accurate when subjects are asked to recall the state of their libido especially at a distant time. Moreover, results from high-dose oral contraceptives used in these studies may not apply to modern low-dose pills.

Prospective, uncontrolled studies

The three prospective, uncontrolled studies measured libido at baseline before oral contraceptive use and then measured it during oral contraceptive use. Results from these studies are summarized in Table 7.6.2. In the Nilsson study,26 women were randomized to four different pills and interviewed five times. Most described their libido as “marked” at baseline, and there were no changes in the proportions describing their libido as “marked, weak, or frigid” during any point in the study. There were also no differences in libido by oral contraceptive type. In the Cullberg et al. study,27 libido was measured twice. On a visual analog scale, “no significant change” in libido occurred during the study compared to baseline; however, no data were given. The authors also stated that 5% of participants reported that their libido diminished. In the Sanders et al. study,28 the authors used validated questionnaires to measure libido (frequency of sexual thoughts) four times during 1 year. More women reported decreases than increases in libido, but most experienced no change. Decreased libido was more common among those discontinuing than continuing oral contraceptives.

These prospective studies indicate that most women had stable libido during oral contraceptive use, with smaller proportions experiencing increases or decreases. These prospective studies provide a more accurate assessment of libido changes than the retrospective studies; comparing changes to baseline decreases effects of restrospective recall. However, two of the three studies used oral contraceptives containing much higher doses than today’s oral contraceptives and were conducted more than 30 years ago.

The lack of a comparison control group in these uncontrolled studies makes it impossible to determine whether changes in libido observed during oral contraceptive use were due to oral contraceptive use or other factors. Among respondents in the National Health and Social Life Survey, a representative sample of the US population, lack of interest in sex during the past year was reported by approximately 30% of women aged 18-44 years.29 Some of these women reporting low libido were probably oral contraceptive users. However, the high prevalence of low libido suggests that substantial numbers of women experience negative changes in libido whether on oral contraceptives or not.

Prospective and cross-sectional controlled studies

This type of study compares libido in oral contraceptive users with libido in a control group of women not using oral contraceptives. The results of these studies are summarized in Table 7.6.3. In the study by Herzberg et al.,30 women starting three different oral contraceptives were compared with a group of intrauterine device users. Scores on a libido scale were collected at baseline and at subsequent clinic visits. Intrauterine device users experienced a modest increase in libido, those continuing oral contraceptives experienced no change in libido, and those discontinuing experienced a modest decrease. The independent effect of oral contraceptives on libido is difficult to determine from this study. The measure of libido also included scores on orgasm and intercourse, and the oral contraceptive and intrauterine device groups were different at baseline on factors such as parity and depressive symptoms, which can also affect libido.

Table 7.6.1. Retrospective studies

Author,

Population,

n

Age years

Measurement

Libido

Libido

Libido

year

country

 

(mean, and/or range given)

technique

increase

decrease

no change

Pincus et al,

ND,

830

ND

Interview

20%

58%

22%

195912

Haiti,

Puerto Rico

           

Goldzieher

FPC,

210

16-40

Interview

30-50%

0%

50-70%

et al., 196213

USA

           

Ringrose,

ND,

100

20-44

Questionnaire

22%

13%

55%

196514

Canada

         

(10% no opinion)

Bakker et al.,

ND,

100

28

Questionnaire

“Subjects

in our study did not indicate that their

196615

USA

   

interview “

basic interest in sexual relations had changed"

Nilsson et al.,

All prescribed

313

20-38

Mailed

2%

21%

28%

196716

Anovid, Sweden

   

questionnaire

   

(49% reported other sexual changes)

Boffa,

Suburban general

140

ND

Questionnaire

4%

36%

ND

1971 7

practice, UK

       

(54% slight, 32% moderately severe, 14% severe)

 

Fortin et al.,

Private practice

70

ND

Interview,

39%

29%

33%

197218

and FPC Canada

   

semistructured and open

     

Bull,

One practice,

476

ND

Interview

ND

10%

ND

197319

UK

   

(“volunteered or elicited")

     

Hall and Hall,

FPC

198

Less than

Interview

53%

15%

32%

19737

UK

 

20 to over 35

       

Gambrell et al.,

FPC

211

 

Interview

15%

20%

65%

19 7 620

USA

           

Hunton,

Private practice,

1090

Less than

Chart review

ND

4%

ND

19 7 621

UK

 

20 to over 40

       

James and

ND,

36

16-35

Interview

ND

11%

ND

Karoussos,

198022

Switzerland

           

Schellen,

ND,

104

31, 18-48

ND

5%

20%

75%

198023

Netherlands

           

Yabur et al.,

ND,

56

18-33

Interview

1%

1%

ND

198924

Venezuela

           

Erkkola et al.,

PCO patients,

162

20-40

Interview

ND

1%, 5%

ND

199025

Finland

       

on diff. OC

 

FPC = family planning clinic, ND = no data given, OC = oral contraception, PCO = polycystic ovary syndrome.

Table 7.6.2. Prospective uncontrolled studies

Author,

year

Population,

Country

n

Age years (mean, and/or range given)

Question

format

Libido

increase

Libido

decrease

Libido no change

Nilsson,

FPC,

159

25

Interview

No change in proportions reporting “frigid,

196726

Sweden

     

weak, or marked" libido

 

Cullberg et al.,

FPC,

99

24

Interview and

ND

ND

“No significant

196927

Sweden

   

questionnaire

   

change"

Sanders et al., 200128

FPC,

University Health Center, USA

107

22

Interview and questionnaire

17%

39%

44%

FPC = family planning clinic, ND = no data given.

Another study comparing continuing oral contraceptive and intrauterine device users reported that more women in the oral contraceptive group experienced decreases in libido than in the intrauterine device group.31 However, no details on the ascertainment of change in libido were given.

Bancroft et al.32,33 used a cross-sectional design to compare oral contraceptive users with non-oral contraceptive users; a small subgroup was followed prospectively for 1 month during which serum androgens and desire were measured. The oral contraceptive users had higher sexual motivation (p <0.01) and sexual desire ratings (p < 0.01) and lower free testosterone levels than the non-oral contraceptive users. However, oral contraceptive users were more likely to have a partner, reported more premarital sexual activity, and reported “more permissive attitudes towards premarital sexual contacts”. Since oral contraceptive users were so different from nonusers, the independent effect of oral contraceptives on libido is very difficult to estimate. Large differences in attitudes and behavior between the groups could obscure hormonally mediated differences.

Randomized, placebo-controlled trials

A control group is essential in order to determine the independent effects of oral contraceptives on libido. However, finding an appropriate control group for an observational study is difficult. As demonstrated by the studies reviewed above, oral contraceptive users may differ in many ways from women not using oral contraceptives. The randomized, controlled trial provides the most efficient study design, since both known and unknown potential confounders are controlled for by the randomization process. We identified four randomized trials that examined the effects of oral contraceptives on libido by comparing an oral contraceptive with placebo or another oral contraceptive. Results of the placebo-controlled studies are summarized in Table 7.6.4.

In the earliest study by Cullberg,34 participants were randomized to one of three oral contraceptives or a placebo. After 2 months, participants were questioned about changes in libido, using the format listed in the Table 7.6.4. With this simple measure, most reported no change. Small and similar proportions of participants reported increases and decreases in libido during the study in all groups, and there were no statistically significant differences between the oral contraceptive groups or between the oral contraceptive and placebo groups.

Table 7.6.3. Prospective and cross-sectional controlled studies

Author,

year

Population,

country

n

Age years (mean, and/or range given)

Measurement

technique

Libido Libido increase decrease

Libido no change

Herzberg et al., 197130

FPC,

UK

218 OC 54 IUD

<24 to >40

Interview,

questionnaire

Those staying on OCs no change Those discontinuing OCs decreased IUD users increased

 

Barnard-Jones,

197331

All patients continuing OC or IUD, UK

100 OC 100 IUD

OC 25 IUD 28

ND

OC 16% 33% IUD 33% 11%

ND

ND

Bancroft et al., 19913233

Student volunteers, Canada

55 OC 55 non-OC

18-28

Validated questionnaires, Leikert scale

OC group higher sexual motivation than non OC group. OC group higher sexual desire scores than non OC group.

FPC = family planning clinic, IUD = intrauterine device, ND = no data given, OC = oral contraception.

Table 7.6.4.  Randomized, placebo-controlled trials

Author,

year

Population,

country

n

Age years (mean, and/or range given)

Measurement

technique

Libido Libido Libido increase decrease no change

Cullberg

197234

Contracepting women, Sweden

320, 80 in each OC group

27

Interview

OC 1 9% 12% ND OC 2 6% 5% ND OC 3 10% 14% ND Placebo 9% 11% ND

Leeton et al., 197835

OC users

undergoing

sterilization

20

35,

27-46

Sexual response score

Mean sex score higher during placebo than OC use.

Graham,

199336

Women with PMS, Canada

20 OC 25 placebo

29

VAS

In two of four menstrual phases, OC group had decreased interest compared with baseline, no change in other phases. No change in interest from baseline in any menstrual phase in placebo group.

Graham et al 199537

., Sterilized women or partners, Scotland and Manila

150,

50 OC 50 POP 50 placebo

32

Standardized interview, questionnaire, daily ratings

Interest in sex decreased in OC group compared with placebo or POP in Scottish women.

No change in interest in sex in OC, POP or placebo in Philippine women.

ND = no data given, OC = oral contraception, PCO = polycystic ovary syndrome, POP = progesterone only pill, VAS = visual analog scale.

In a much smaller study, Leeton et al.35 examined the sexual effects of oral contraceptives in women undergoing surgical sterilization. Established oral contraceptive users were randomized to receive either an oral contraceptive for 1 month and then placebo for the next month or the same treatments in reverse order. During both months, participants answered questions related to frequency, enjoyment, and orgasm as well as interest and thoughts about sex. In this crossover design, participants were asked to compare their current experience with the previous month. “Sex scores” were lower (indicating worse functioning) during oral contraceptive use than during placebo use. However, effects on libido specifically cannot be determined; scores combined responses for the other measures of sexual functioning as well as libido. These results may also underestimate any negative effect of oral contraceptives on libido, since the study included only satisfied, stable oral contraceptive users, who may not be as susceptible to negative effects.

In a more recent study, Graham and Sherwin36 examined the effects of oral contraceptives on sexuality as a subanalysis of a trial designed to examine efficacy of oral contraceptives for treatment of premenstrual syndrome. At baseline and over 3 months, participants were asked to rate their daily levels of sexual interest. Participants were randomized to receive oral contraceptive or placebo. Attrition in this study was high; of the 82 enrolled, 23 withdrew. In the oral contraceptive group, sexual interest ratings decreased during the menstrual and postmenstrual phases compared with baseline, but not during other phases of the cycle. No changes from baseline were observed in the placebo group. These results suggest decreased sexual interest was caused by oral contraceptive use. However, high discontinuation could lead to over- or under-estimation of the true effect.

The most recent study, also conducted by Graham et al.,37 has several important strengths. This study was the only randomized clinical trial designed to examine effects of oral contraceptive use on libido as a primary outcome and had a much lower discontinuation rate (4/150) than other studies. This study also included women from a country other than the USA, Canada, or Europe. Sterilized women or women with sterilized partners were randomized to receive either a combined oral contraceptive, a progesterone-only pill, or a placebo for 4 months. Standardized, structured interviews and questionnaires were used to assess sexual function.

Baseline characteristics and effects on sexual interest were different in the two groups of women. The Manila women were less educated, had more children, were more likely to work as unskilled laborers, and reported less interest in and enjoyment of sex than the Scottish women. Among the Scottish women, but not the Philippine women, ratings of sexual interest and sexual activity declined in the oral contraceptive group, but not in the progesterone-only pill or placebo groups.

The authors postulated that the differential effect of oral contraceptive versus progesterone-only pill among Scottish women could be attributed to oral contraceptive-mediated changes in testosterone that do not occur on progesterone-only pills. These results also highlight how reactions to oral contraceptives may depend on user characteristics. Changes in sexuality associated with oral contraceptive use were greater among women with a more positive experience of their sexuality at baseline than among women with a more negative experience of their sexuality.

Conclusion

Most women spend decades of their lives avoiding pregnancy, and oral contraceptives provide an effective, safe contraceptive option. Oral contraceptives are the most widely used hormonal method, and oral contraceptive-mediated effects on sexual functioning, whether positive or negative, could affect large numbers of women. Published research exploring the impact of oral contraceptives on sexuality has focused on libido. Such an effect is biologically plausible; oral contraceptives significantly decrease circulating androgens.

Most studies examining oral contraceptive-mediated effects on libido were retrospective and uncontrolled, used non- standardized methods to measure libido, and were conducted decades ago when much higher-dose oral contraceptives were in use. These studies suggest oral contraceptive use was more often associated with stable or increased rather than decreased libido. The few prospective, uncontrolled studies found that oral contraceptive use was associated with stable libido among the vast majority of users, with small numbers experiencing increases or decreases.

Controlled, observational studies have compared oral contraceptive users with nonusers and users of other contraceptive methods such as the intrauterine device. Oral contraceptive users in these studies had both higher and lower libido than nonusers. However, users and nonusers were different in many respects. Additionally, in cross-sectional studies, there is no way to determine whether oral contraceptive use increased libido, or whether those with increased libido were more likely to use oral contraceptives. When oral contraceptive users were compared with intrauterine device users, the effect of oral contraceptives was difficult to determine because the groups were different on many factors which can affect libido (age, parity).

Results from the four randomized, placebo-controlled trials identified were mixed. In the largest trial, changes in libido were uncommon and similar among the oral contraceptive and placebo groups. A small trial among women with premenstrual syndrome found that oral contraceptive use was associated with a decrease in sexual interest compared with placebo. A small study of sterilized women found that sexual functioning was worse in the oral contraceptive than placebo group, but effects on libido were not assessed independently. In the most recent randomized, clinical trial, oral contraceptive use was associated with decreased libido in sterilized women compared with placebo or a progesterone-only pill. However, this effect was limited to women with high baseline sexual functioning; no decreases in libido occurred among women with worse baseline sexual functioning. None of these studies meet the criteria for high-quality randomized clinical trials specified by groups such as CONSORT.38

When oral contraceptives became widely available in the 1960s, researchers postulated that determining the effect of oral contraceptives on libido would be difficult. As of 2004, no well- conducted randomized clinical trial has adequately addressed this question. Existing evidence suggests that libido is usually stable on oral contraceptives, but that decreases or increases may occur in some women. The social context of oral contraceptive use may determine the clinical importance of small effects on libido. For instance, increased contraceptive security or improvement in acne with oral contraceptive use may cause an increase in libido that overrides a hormonally driven decrease. In other populations, such as women who are sterilized and derive no contraceptive benefit from oral contraceptives, users may be sensitive to hormonally driven negative effects on libido.

Women and health-care providers often overestimate the negative effects of oral contraceptives and underestimate the positive effects. Better research is needed to provide a clear message to women on how oral contraceptive use affects libido. Until then, providers must be cautious in attributing negative experiences to oral contraceptives, and be willing to explore other explanations for the common experience of decreased libido. Ways in which oral contraceptives could positively affect sexuality, such as decreased risk of pregnancy, decreased bleeding, decreased pain, or improved acne and hirsutism, remain unexplored.

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