Between Oral Contraceptive Users and. Age of Menarche, and Sociosexual

Transcription

1 In: Progress in Biological Psychology Research ISBN: Editor: Giuseppina A. Conti, pp Nova Science Publishers, Inc. Chapter 3 Pre-existing Hormonal Differences Between Oral Contraceptive Users and Nonusers? Evidence from Digit Ratio, Age of Menarche, and Sociosexual Orientation Kirsten A. Oinonen *, Janelle A. Jarva and Dwight Mazmanian Department of Psychology, Lakehead University, 955 Oliver Road, Thunder Bay Ontario, P7B 5E1 Canada Abstract Many studies in evolutionary psychology and behavioural endocrinology employ women who are not using hormonal contraceptives. Such a sample is typically used to examine menstrual cyclicity in behaviour (e.g., mate preferences) or the effects of endogenous hormones on behaviour. However, women who do not use hormonal contraceptives (i.e., nonusers and never-users) may differ from current users and ever-users. It is important that researchers are aware of population differences between hormonal contraceptive users and nonusers to prevent inappropriate generalization of findings from nonusers to users. The present study of 481 women provides indirect evidence of possible hormonal differences between oral contraceptive (OC) users, previous users, and nonusers. Compared to never users, current OC users had a lower second to fourth digit ratio (2D:4D) (suggesting higher prenatal testosterone exposure), a more unrestricted sociosexual orientation, earlier age of menarche, a higher rate of hormonal disorders, a higher likelihood of being in a relationship, and a higher rate of both non-oc medication use and illegal drug use. Previous OC users had the highest 2D:4D, the highest rate of hormonal disorders, the most non-oc hormonal medication use, the highest rate of premenarchial habitation with an unrelated man (e.g., a step-father), and a more unrestricted sociosexual orientation than never users. A possible OC-related mood stabilization effect was also found. The 2D:4D measures suggest that current, previous, and never users may be hormonally different groups, and that high 2D:4D may be a potential marker of women who experience OC-related side effects (and subsequently discontinue use). These findings are relevant to all researchers using human female participants to examine hormonal effects, and to researchers examining the risk of sexually transmitted diseases. * address: koinonen@lakeheadu.ca, tel: (807) , fax: (807)

2 96 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian Introduction Approximately 84% of women between the ages of 15 and 44 take oral contraceptives (OCs) at some point in their lives (Fisher et al., 1999). Many of these women discontinue hormonal contraceptives due to side effects (Rosenberg & Waugh, 1998). Although a substantial amount of research indicates that hormones affect mood, cognition, and behaviour (e.g., Sherwin, 1996), all women who take OCs do not experience similar mood, cognitive, or somatic side effects or benefits. In fact, some women report improved mood, while others report depression (Oinonen & Mazmanian, 2002). Hormonal differences prior to OC use may contribute to the presence or absence of different side effects that women experience when taking OCs (Oinonen & Mazmanian, 2002). Both circulating hormone levels (activational effects) and hormone receptor sensitivity (organizational effects) may predict side effect profiles. However, it has been difficult to examine the relative roles that organizational and activational hormonal effects play in OC-related side effects, primarily due to difficulties in measuring hormone receptor sensitivity. Only a few studies have specifically examined hormonal differences between OC users and nonusers, and it is often not clear whether these differences are pre-existing or the result of OC use (e.g., Alexander et al., 1990; Bancroft et al., 1991a; Graham et al., 1997). We are not aware of any studies that have specifically set out to examine indicators of pre-existing hormonal differences between current, previous, and never users (but see Jernstrom & Olson, 1997). Given that many women discontinue OCs due to adverse side effects resulting from the hormones, it is likely that women who discontinue OCs (previous users) differ from current OC users in terms of organizational hormonal effects (genetic or biological). Evidence of hormonal differences between current OC users, previous users, and never users would be relevant for two important reasons. First, hormonal differences might explain why some women report specific types of OC side effects while others do not. Pre-existing hormonal difference indicators might be useful markers of hormonal sensitivity to OCs or to certain exogenous hormone compounds or ratios of the compounds (Oinonen & Mazmanian, 2002). Second, the majority of research on endogenous female hormones is done using freecycling women (e.g., Hampson, 1990). If free-cycling women differ hormonally from women taking oral contraceptives, research findings from one group may not generalize to the other. Thus, hormonal differences between OC user groups might suggest possible markers or predictors of OC sensitivity, as well as the need to measure and possibly control for such variables when examining the effects of endogenous hormones in free-cycling women (e.g., menstrual cycle research) or the effects of exogenous hormones in OC users. The ratio of the second to the fourth digit (2D:4D) is a sexually dimorphic measure that is believed to reflect prenatal hormone exposure (organizational effects) (e.g., Manning et al., 1998). It has also been suggested as a phenotypic measure of transactivation activity of the androgen receptor gene (Manning, Bundred, et al., 2002). Therefore, 2D:4D has the potential to be a useful measure of individual differences in hormone sensitivity. Women tend to have higher 2D:4D (close to 1), indicating roughly equivalent finger ratios, while men tend to have lower 2D:4D (less than 1), indicating a smaller second than fourth digit (e.g., Manning et al., 2000). The Hox genes control development of both the digits and genitals (Kondo et al., 1997), and there is some evidence that finger ratios are set at about the 13 th week of gestation (Garn et al., 1975). Thus, it is has been suggested that finger ratios reflect the amount of

3 Hormonal Differences in Oral Contraceptive Users? 97 testosterone exposure in the womb as the Leydig cells of the testes stimulate the production of testosterone (Manning et al., 1998). In women, levels of testosterone present in the womb during digit development would also affect 2D:4D. Lower 2D:4D is reflective of higher testosterone exposure, as the fourth digit is believed to be more sensitive to testosterone growth effects. Examination of hormone levels in women indicates that mothers with lower 2D:4D have higher levels of testosterone in their fetal amniotic fluid (Manning, 2002). A meta-analysis of both male and female samples suggests that 2D:4D is unrelated to concurrent adult hormone levels (Hönekopp et al., 2007). However, a study of women who have never used OCs suggests a positive relationship between right hand 2D:4D and adult estradiol levels (McIntyre et al., 2007). While the majority of the evidence suggests that 2D:4D reflects only prenatal testosterone exposure, it may not yet be possible to rule out an association between 2D:4D and women s current estradiol levels. A number of reproductive, personality, and sexuality variables are associated with 2D:4D in women. Higher 2D:4D is associated with: higher rates of marriage and higher numbers of offspring (Manning et al., 2000), lower rates of congenital adrenal hyperplasia (CAH; Brown et al., 2002), more predictable menstrual cycles in free-cyclers (Oinonen & Mazmanian, unpublished), earlier onset of breast cancer in individuals who develop the disease (Manning & Leinster, 2001), lower levels of assertiveness (Wilson, 1983), a more feminine sex-role identity (Csatho et al., 2003), a more unrestricted sociosexual orientation, and higher rates of premenarchial habitation with an unrelated man (Oinonen & Mazmanian, 2003). Low 2D:4D is also associated with homosexual orientation (Williams et al., 2000) and a greater likelihood of defining oneself as a butch versus femme lesbian (Brown et al., 2002). Thus, evidence is accumulating to suggest 2D:4D as a useful predictor of possible organizational effects of hormones in women. As noted above, research examining hormonal differences between OC user groups has primarily focused on concurrent measures of blood hormone levels. Besides the fact that these levels differ across the menstrual cycle, the resulting hormonal measures do not necessarily provide information about hormone receptor sensitivity. The degree to which an individual s hormone receptors respond to hormones may be more important than endogenous hormone levels in determining hormonal effects. More valid indicators of a woman s sensitivity to hormones may be actual physiological indicators of hormonal effects such as 2D:4D, age of menarche, body mass index (BMI), waist-to-hip ratio (WHR), and possibly behavioural measures such as sociosexual orientation (Oinonen & Mazmanian, 2002). Such measures may be valuable in estimating a woman s sensitivity to specific types of hormonal effects. The present study is an exploratory examination of potential hormonal differences between current OC users, previous users, and never users. A total of 481 women met inclusion criteria and completed an initial questionnaire (251 current users, 148 never users, 82 previous users) that examined group differences in age of menarche, BMI, premenarchial habitation with unrelated men, medical and hormonal conditions, medication use, relationship status, family psychiatric history, and mood. A subsample (50 OC users, 60 nonusers) completed a more detailed questionnaire and had body measurements taken in order to examine group differences in 2D:4D, sociosexuality, WHR, BMI, alcohol and drug use, and smoking status.

4 98 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian Method Participants The participants in phase one of this study were 579 female volunteers recruited from university undergraduate classes (primarily introductory psychology classes) and the community to participate in a study of neuroendocrine effects on physical, psychological, and emotional variables. The community volunteers were obtained through advertisements posted on bulletin boards throughout the city. The following participants were excluded from analyses: (a) women not within the 17 to 30 age range (n = 63); (b) women taking Depo Provera (n = 11); and (c) women taking Diane-35 (n = 24), a hormonal treatment that is not currently approved for sole use as an OC in Canada. Thus, data from a total of 481 participants (mean age = 20.23, SD = 2.72) were used for analysis. The participants were divided into three groups: current OC users (n = 251), never users (n = 148), and previous OC users (n = 82). Introductory psychology student volunteers received course credit for participation. Of the 481 women in phase one, two groups of women (total N = 110) were selected to participate in phase two of the study (mean age = 19.91, SD = 2.42). The first group (non users) was comprised of 60 women who fit the following inclusion criteria: (a) no use of oral contraceptives during the past six months, (b) age within the 17 to 30 range, (c) no medical conditions that affect hormones or mood (e.g., hypothyroidism, depression), (d) no use of medications that affect hormones or mood (e.g., thyroid medications, antidepressants), (e) not pregnant, (f) a predictable menstrual cycle, and (g) a menstrual cycle ranging between 25 and 35 days. These women participated in a larger study (Oinonen & Mazmanian, 2007), of which the current study was a small part. The second group (OC users) was comprised of 50 women who met the above criteria, with the exception that they were currently taking oral contraceptives, and had been taking them for at least three months. It should be noted that while these OC users reported a predictable menstrual cycle ranging between 25 and 35 days, we did not obtain information about their cycle prior to OC use. Introductory psychology student volunteers received course credit for participation. Procedure and Measures In phase one, participants completed the Screening Questionnaire (see below) and were informed that a research assistant would contact them in the next few weeks if they were selected for phase two of the study. The data collected from phase one was used to compare groups of OC users, never users, and previous users (N = 481). These data are likely representative of population differences between university student OC users, previous users, and never users. For phase two, two groups of participants (OC users and nonusers) were selected based on the inclusion criteria described above. Each woman was contacted by telephone by one of the five female data collectors, a brief description of the questionnaire and the body measurements was given, and a laboratory appointment was arranged. During the lab appointment, each woman completed the Session Questionnaire and had body measurements taken (see below). Data collected during phase two represents a more detailed examination of

5 Hormonal Differences in Oral Contraceptive Users? 99 differences between OC users and nonusers based on a sample of women in which the nonusers are reflective of women who would normally be selected to participate in hormone menstrual cycle research. Screening Questionnaire. The Screening Questionnaire was developed for the study and included basic demographic information (e.g., age, education, and relationship status); medical and reproductive information; and the Positive and Negative Affect Schedule (PANAS) (Watson et al., 1988). The medical information section included questions about height, weight, medication use, diagnosed medical conditions, age of menarche, menstrual cycle length and regularity, pregnancy, history of oral contraceptive use, and family psychiatric history. The PANAS was included as a measure of affect or mood. It consists of 20 affect descriptors (10 make up the Positive Affect Scale and 10 make up the Negative Affect Scale) and requests that each participant rate the degree to which they have experienced that emotion today. The PANAS employs a Likert rating scale that ranges from 1 (very slightly or not at all) to 5 (extremely) and has been found to have good psychometric properties (Watson et al., 1988). Session Questionnaire. The Session Questionnaire included questions regarding health behaviours (e.g., smoking status, frequency of alcohol and illegal drug use, and hours of sleep), family medical history, the Sociosexual Orientation Inventory (SOI) (Simpson & Gangestad, 1991), and the PANAS (described above). The SOI is a measure of sociosexuality or the degree to which individuals require prerequisites such as time, attachment, commitment, and love prior to entering into a sexual relationship. Restricted individuals tend to require more time, commitment, attachment, and love while unrestricted individuals require relatively less of each. The SOI contains five indices: (a) the number of sexual partners in the past year; (b) the number of different sexual partners foreseen in the next five years; (c) the number of times having engaged in sexual intercourse with a partner on only one occasion; (d) the frequency of sexual fantasy involving partners other than the current one (coded on an 8-point scale); and (e) three attitudes toward engaging in casual and uncommitted sexual intercourse (each coded on a 9-point Likert scale). The total SOI score was calculated by unit-weighting each of the five components by transforming each to z- scores, and then calculating the mean of the five z-scores (e.g., Simpson & Gangestad, 1991). Body Measurements. Measures of waist and hip circumference were taken using K-E anthropometric tape. Body height was measured using a tape measure. Weight was measured in kilograms using an electronic scale. Mitutoyo Electronic Digital calipers (Model MIT ) measuring to 0.01 mm were employed in the measurement of the length of digits 2 to 5. Both left- and right-sided digits were measured twice to reduce measurement error and to assess reliability. Digits were measured on their ventral surface from the basal crease to their tip. These measurements have shown a high degree of test-retest reliability, rs =.81 to.89 (Manning et al., 1998). Body mass index (BMI), a measure of body fat, was calculated in kg/m 2 using weight (kg) and height (m). Waist-to-hip ratio (WHR) was calculated by dividing waist circumference by hip circumference. Statistical Analyses Two main types of analyses were used. For each phase of the study, group differences in the continuous dependent variables were examined using one-way MANOVA, and significant

6 100 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian main effects were followed up with univariate ANOVAs. The Tukey Honestly Significant Difference (HSD) adjustment was used to control for type I errors in post-hoc tests. Group differences in the discrete variables were examined individually using chi-square. Alpha levels were set at.025. Results Data Screening and Examination of Assumptions The variables were examined for outliers, normality, and univariate and multivariate assumptions using techniques suggested by Tabachnick and Fidell (2001). For the phase one data, the distributions of BMI, age of menarche, negative affect, and positive affect were examined for each group. Due to severe positive skewness, the variables BMI and negative affect were transformed to normality using the inverse transformation. For ease of understanding, untransformed means and 95% confidence intervals (95% CIs) are reported for these transformed variables. Only three outliers were found and these were for the age of menarche variable (ages 8, 17, and 17 for the OC users). Since these values were sampled from the target population and only represented one unit value smaller or larger than the next most extreme scores, no changes were made to the values. For the phase two data, the distributions of nine variables were examined for each group: total SOI score, negative affect score, positive affect score, age, alcohol consumption score, measured BMI, mean 2D:4D, WHR, and age of menarche. As four variables were positively skewed, the following transformations were used to obtain normal distributions: a logarithmic transformation of total SOI scores, an inverse transformation of negative affect scores, a square root transformation of alcohol consumption scores, and a logarithmic transformation of BMI. However, untransformed means and 95% confidence intervals (95% CIs) are reported. Four outliers were found (each for a different variable) and each was changed to one unit value smaller or larger than the next most extreme score, as recommended by Tabachnick and Fidell (2001). Phase One Descriptive Data. Examination of the rates of OC use revealed that 52% of the women were current OC users and that 69% were ever users. Similar rates of current and ever use of OCs, respectively, were found when the 17 to 25 age group (54% and 68%, n = 443) and the 17 to 20 age group (54% and 67%, n = 347) were examined. For the full sample, those women currently taking OCs had been taking them for a mean of (SD = 29.16) months (range 3 to 180) while the previous users had stopped taking OCs a mean of (SD = 32.07) months ago. Group means and standard deviations (or 95% CIs) for the four continuous dependent variables are listed in Table 1. Those for the discrete variables are listed in Table 2.

7 Hormonal Differences in Oral Contraceptive Users? 101 Table 1. Means and Standard Deviations (or 95% Confidence Intervals) for Four Variables used to Examine Group Differences between Current OC Users, Never Users, and Previous Users (Phase One). Variable Current OC Users Never Users Previous Users n = 242 n = 139 n = 80 BMI (17.81, 30.99) (17.41, 33.14) (17.21, 35.36) Negative Affect (9.58, 33.51) (9.28, 35.45) (9.49, 31.22) Positive Affect (7.78) (7.21) (7.67) Age of Menarche** (1.33) (1.27) (1.31) *p <.025. **p <.01. ***p<.001. Table 2. Raw Frequencies (Percentages) for Eight Categorical Variables Used to Examine Group Differences Between Current OC Users, Never Users, and Previous Users (Phase One). Variable Current OC Users Never Users Previous Users n = 251 n = 148 n = 82 Relationship Status *** Partner 159 ( 63.3 ) 58 ( ) 42 ( ) No Partner 92 ( 36.7 ) 90 ( ) 40 ( ) Family Psychiatric History (ns = 213, 120, 67) Yes 141 ( ) 66 ( ) 41 ( ) No 72 ( ) 54 ( ) 26 ( ) Males in Home Before Menarche Yes 42 (16.80 ) 15 (10.10 ) 19 (23.20 ) No 208 (83.20 ) 133 (89.90 ) 63 (76.80 ) Medical Condition Yes 66 ( ) 28 (18.90 ) 27 ( ) No 185 ( ) 120 (81.10 ) 55 ( ) Hormonal Condition ** Yes 12 (4.80 ) 1 (0.70 ) 8 (9.80 ) No 239 (95.20 ) 147 ( ) 74 ( ) Medication Use** Yes 56 (22.40 ) 14 (9.50 ) 21 ( ) No 194 (77.60 ) 134 ( ) 61 ( ) Hormonal Medication Use Yes 15 (6.00 ) 4 (2.70 ) 8 (9.80 ) No 236 (94.00 ) 144 (97.30 ) 74 (90.20 ) Psychotropic Medication Use Yes 16 (6.40 ) 4 (2.70 ) 5 (6.10 ) No 235 (93.60 ) 144 (97.30 ) 77 (93.90 ) p <.05 (ns trend). *p <.025. **p <.01. ***p<.001. Continuous Variables. A one-way between subjects MANOVA was performed on the four dependent variables with OC group as the independent variable. Pillai s Trace criterion indicated that the combined dependent variables did not differ significantly among the three groups, F(8, 912) = 1.67, p =.10, partial eta 2 =.01. Due to the presence of a weak nonsignificant trend in the MANOVA, univariate follow-up ANOVAs were performed. No

8 102 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian significant group differences were found for BMI, negative affect, or positive affect, Fs(2, 458) = 0.76, 0.24, 0.57, all p >.05, respectively. However, a highly significant group effect was found for age of menarche, F(2, 458) = 5.12, p =.006, partial eta 2 =.02. Never users had a significantly older age of menarche than both current OC users (p =.021) and previous OC users (p =.014), but current and previous users did not differ in age of menarche (p =.66). A similar pattern of earlier age of menarche for previous users than never users was found when the one-way ANOVA was repeated on the following more homogeneous age groups: ages 17 to 25, F(2, 422) = 5.98, p =.003, partial eta 2 =.03; ages 17 to 20, F(2, 330) = 4.60, p =.01, partial eta 2 =.03; and ages 20 to 30, F(2, 185) = 3.46, p =.033, partial eta 2 =.04. Dichotomous Variables. Chi-square analyses were conducted to examine group differences in relationship status (partner, no partner), diagnosed medical conditions (yes, no), use of medications other than OCs (yes, no), habitation with males who are biologically unrelated prior to menarche (yes, no), and family psychiatric history (yes, no). Relationship status and oral contraceptive status were found to be significantly related, χ 2 (2, N = 481) = 22.14, p <.001. Not surprisingly, current OC users were significantly more likely to have a partner than never users, χ 2 (1, N = 399) = 21.90, p <.001. There were nonsignificant trends towards OC users being more likely to have a partner than previous users, χ 2 (1, N = 333) = 3.80, p =.05; and for previous users to be more likely to have a partner than never users, χ 2 (1, N = 230) = 3.108, p =.078. A nonsignificant trend was found between report of a medical condition and oral contraceptive status, χ 2 (2, N = 481) = 5.86, p =.05. Follow-up analyses revealed that previous users were more likely to have a medical condition than never users, χ 2 (1, N = 230) = 5.69, p =.017, but that OC users were not significantly more likely to report a medical condition than either never users, χ 2 (1, N = 399) = 2.81, p =.09; or previous users, χ 2 (1, N = 333) = 1.35, p =.24. Further investigation of medical status revealed a significant relationship between oral contraceptive status and report of a hormonal disorder, χ 2 (2, N = 481) = 10.64, p =.005, such that previous users were more likely to report a hormonal disorder than never users, χ 2 (1, N = 230) = 11.57, p =.001. While there was a nonsignificant trend towards a higher rate of hormonal disorders in current users than never users, χ 2 (1, N = 399) = 4.98, p =.026, no significant difference in prevalence was found between current and previous OC users, χ 2 (1, N = 333) = 2.71, p =.10. A significant relationship was found between medication use (other than OCs) and oral contraceptive status, χ 2 (2, N = 480) = 12.98, p =.002. Never users were significantly less likely to be taking a medication than either current users, χ 2 (1, N = 398) = 10.74, p =.001; or previous users, χ 2 (1, N = 230) = 10.67, p =.001. However, current and previous users did not differ in their likelihood of taking a medication, χ 2 (1, N = 332) = 0.36, p =.55. Type of medication use was also examined. No relationship was found between oral contraceptive status and use of psychotropic medications, χ 2 (2, N = 481) = 2.71, p =.26. However, there was a nonsignificant trend suggesting a relationship between the use of a non-oc hormonal medication and oral contraceptive status, χ 2 (2, N = 481) = 5.09, p =.079. A higher proportion of previous users reported current use of a hormonal medication compared to never users, χ 2 (1, N = 230) = 5.31, p =.021. There were no differences in hormonal medication use between current users and either previous users, χ 2 (1, N = 333) = 1.37, p =.24; or never users, χ 2 (1, N = 399) = 2.20, p =.13.

9 Hormonal Differences in Oral Contraceptive Users? 103 There was a nonsignificant trend towards a relationship between oral contraceptive status and premenarchial habitation with a man who was not biologically related, χ 2 (2, N = 480) = 7.09, p =.029. Previous users were much more likely than never users to have had a nonbiological male living in their home, χ 2 (1, N = 230) = 7.11, p =.008. There was a nonsignificant trend towards more current users than never users having had a nonbiological male living in their home, χ 2 (1, N = 398) = 3.37, p =.067; but no difference between current and previous users, χ 2 (1, N = 332) = 1.67, p =.20. Likelihood of having a positive family psychiatric history did not differ significantly as a function of oral contraceptive status, χ 2 (2, N = 400) = 4.11, p =.13. Phase Two Reliability of Digit Measurements. Mean 2D:4D ratios for the 110 women in phase two were 0.98 (SD = 0.03) for the right hand, 0.98 (SD = 0.04) for the left hand, and 0.98 (SD = 0.03) for both hands. Repeatabilities calculated using intraclass correlation coefficients were as follows: (a) digit 2 (right hand =.99, left hand =.99); (b) digit 4 (right hand =.99, left hand =.96); and (c) 2D:4D (right hand =.89, left hand =.84). These repeatabilities are high and comparable to those obtained by other researchers (e.g., Manning et al., 1998). Continuous Variables. Group means and standard deviations, or 95% CIs, for the nine variables are listed in Table 3. A one-way MANOVA conducted on all nine variables with OC group (OC user, nonuser) as the independent variable revealed that the combined dependent variables did differ as a function of OC status, F(9, 99) = 4.35, p <.001, partial eta 2 =.28. Follow-up univariate ANOVAs were conducted to examine differences between OC users and nonusers. As outlined in Table 3, OC users had a significantly higher or more unrestricted SOI score, a lower or more masculine mean 2D:4D, an earlier age of menarche, and a higher mean positive affect score than nonusers. There were also nonsignificant trends towards OC users being younger and having lower BMI and WHR than nonusers. No group differences were found for the negative affect or alcohol consumption scores. Table 3. Comparison of OC Users and Nonusers in Phase Two: Group Means, Standard Deviations (or 95% Confidence Intervals), and ANOVA results Variable OC Users Nonusers F df p (n=50) (n=60) Total SOI Score a (-0.28, 0.02) (-0.49, 0.29) , Mean 2D:4D 0.97 (0.03) 0.99 (0.03) , Age of Menarche (1.00) (1.42) , BMI (22.63, 24.45) (23.76, 26.63) , WHR 0.76 (0.06) 0.78 (0.07) , Positive Affect (7.85) (6.66) , Negative Affect (13.00, 15.13) (12.84, 14.04) , Alcohol Use 2.20 (1.83, 2.60) 1.84 (1.51, 2.20) , Age (17.39, 20.85) (17.91, 22.51) , a Scores represent z-scores calculated using the entire sample.

10 104 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian In order to further clarify the relationship between SOI and OC status, the sample was divided into current (M = -0.14, 95% CIs = to 0.02, n = 50), never (M = -0.46, 95% CIs = to 0.35, n = 50), and previous (M = -0.03, 95% CIs = to 0.29, n = 10) users. The total SOI scores differed as a function of group in this sample of women aged 17 to 30, F(2, 107) = 8.22, p <.001; and differed similarly in the 17 to 45 age group (ns = 51, 50, 25), F(2, 123) = 8.74, p <.001. For both age group samples, never users had a lower or more restricted SOI score than both current (both ps =.001) and previous users (ps =.019,.005), respectively. The total SOI score did not differ between the current and previous users for either the age 17 to 30 sample (p =.80), or the 17 to 45 (p =.99) sample. Table 4. Group Differences in Mean Scores on Items in the Sociosexual Orientation Inventory for Current Oral Contraceptive Users and Never Users (Phase Two) Variable OC Users Never Users F p n = 50 n = 50 (1, 98) Number of Sexual Partners in the Past Year 1.62 ( 1.32 ) 0.44 ( 0.81 ) Number of Sexual Partners Foreseen in Five Years 2.44 ( 2.14 ) 1.84 ( 1.13 ) Number of One Night Stands 0.90 ( 1.68 ) 0.14 ( 0.41 ) Fantasy a 2.02 ( 1.70 ) 2.24 ( 1.51 ) Sex without Love is ok Belief 4.00 ( 2.48 ) 3.00 ( 2.51 ) Casual Sex is ok Belief 2.86 ( 2.29 ) 1.90 ( 1.51 ) Attachment Needed for Sex Belief 6.82 ( 2.23 ) 7.80 ( 1.65 ) Note. For the three belief items, which were rated on a scale from 1 to 9, higher scores represent greater agreement with the belief. a 48 OC users and 42 nonusers; df = 1, 88 In light of the similar sociosexual orientation scores for current and previous users, further analyses on the raw scores of the seven SOI items were conducted using the current and never user groups to determine which items differed based on OC group (see Table 4 for means and standard deviations). An overall one-way MANOVA on the seven variables indicated a significant group effect, F (7, 82) = 4.03, p =.001. As outlined in Table 4, followup univariate ANOVAs found that, compared to never users, OC users reported the following: (a) significantly more sexual partners in the past year, (b) more lifetime one-night stands, (c) more agreement with the statement I can imagine myself being comfortable and enjoying casual sex with different partners, and (d) less agreement with the statement I would have to be closely attached to someone (both emotionally and psychologically) before I could feel comfortable and fully enjoy having sex with him/her. There was also a strong trend towards OC users agreeing more that Sex without love is ok, compared to never users. When relationship status was controlled using analysis of covariance, OC users predicted that they would have a significantly higher number of sexual partners in the next five years compared to never users, F(1, 97) = 5.33, p =.023. Thus, both sociosexual beliefs and behaviour differed between OC users and never users. A comparison of left and right 2D:4D revealed that while OC users (M = 0.97, SD = 0.04) had a significantly lower left hand 2D:4D than nonusers (M = 0.99, SD = 0.04), F(1, 108) = 6.98, p =.009; there was no group difference for right hand 2D:4D between the OC users (M = 0.98, SD = 0.03) and nonusers (M = 0.99, SD = 0.03), F(1, 108) = 1.37, p =.245.

11 Hormonal Differences in Oral Contraceptive Users? 105 Despite a small sample of previous users, a one-way ANOVA comparing current users (M = 0.97, SD = 0.04, n = 50), never users (M = 0.99, SD = 0.04, n = 50), and previous users (M = 1.01, SD = 0.04, n = 10) indicated that left 2D:4D differed as a function of OC status, F(2, 107) = 4.52, p =.013. Current users had a significantly lower mean ratio than the previous users (p <.025), and there was a trend towards current users having lower left 2D:4D than the never users (p =.08). Previous research suggests that 2D:4D does not change with age (Manning et al., 1998), and no relationship between age and 2D:4D was found in the present data, r (n = 126) =.05, p =.60. Therefore, in order to increase the sample of previous users, another analysis was carried out in which women over the age of 30 and a sample of 66 men (mean age = years, SD = 4.10) (all men and women were drawn from the same population as the other samples) were included in order to compare men, current OC users, never users, and previous users. For the left hand, right hand, and both hands, 2D:4D differed as a function of hormonal group, Fs (3, 188) = 4.19, 3.74, 5.06; ps =.007,.012,.002, respectively. As illustrated in Figure 1, Tukey LSD post hoc tests revealed that for the more sensitive left 2D:4D, men had significantly lower 2D:4D than previous users (p =.008) and never users (p =.016), but did not differ from current OC users (p =.993). Current users had significantly lower 2D:4D than previous users (p =.011) and never users (p =.024), but there was no difference between never users and previous users (p =.47). The same pattern was seen for the right hand and the mean of both hands, with some of the differences significant and others nonsignificant trends Mean Left 2D:4D Men OC Users Never Users Previous Users Hormonal Group Figure 1. Mean left-hand 2D:4D as a function of hormonal group. Men (M = 0.971, SD = 0.031, n = 66) and current OC users (M = 0.971, SD = 0.042, n = 50) had similar and significantly lower 2D:4D than both never users (M = 0.988, SD = 0.035, n = 51) and previous OC users (M = 0.994, SD = 0.031, n = 25), whose 2D:4D ratios did not differ significantly. Error bars represent the standard error of the mean.

12 106 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian Table 5. Group Differences Between OC Users and Nonusers for Four Categorical Variables: Raw Frequency (Percentages) and Chi-Square Test Results (Phase Two) Variable OC Users Nonusers χ 2 df, N p n =50 n=60 Relationship Status Partner 29 (58.00) 26 (43.30) , No Partner 21 (42.00) 34 (56.70) Males in Home Yes 8 (16.00) 7 (11.70) , No 42 (84.00) 53 (88.30) Smoker Yes 5 (10.00) 4 (6.70) , No 45 (90.00) 56 (93.30) Illegal Drug Use Yes 14 (28.00) 6 (10.20) , No 36 (72.00) 53 (89.98) Dichotomous Variables. Chi-square analyses were conducted to examine group differences in relationship status (partner, no partner), habitation with an unrelated man prior to menarche (yes, no), smoking status (smoker, non-smoker), and illegal drug use (yes, no) in the phase two sample. The frequencies and percentages for each variable in each group are presented in Table 5 along with the chi-square results. The only significant finding was a higher rate of illegal drug use in the OC user group than the nonuser group. While not presented in detail here due to reliability and validity questions about participants definitions of family history, no group differences were found in terms of reported family histories of cancer, diabetes, cardiovascular disease, or thyroid disorders, all ps >.44. Conclusion Summary of the Findings In this largely undergraduate (and primarily first year) university student population, over half of the women (52 to 54%) were currently taking OCs, and over two-thirds of the women (67 to 69%) had ever taken OCs. Furthermore, 79% (202 of 257) of the women older than 19 had ever taken OCs. Thus, lifetime prevalence of ever using OCs likely exceeds 80% in this population. The results from the phase one sample of 481 women indicated five highly significant differences between OC users groups that may reflect pre-existing or OC-initiated hormonal differences. First, never users had a significantly older age of menarche than both current and previous users. Second, current OC users were more likely to be in a relationship than women who had never used OCs. Third, current OC users and previous users reported higher rates of hormonal disorders than never users. Fourth, a higher percentage of OC users and previous users were taking a non-oc medication than never users, and previous users

13 Hormonal Differences in Oral Contraceptive Users? 107 were more likely to be taking a hormonal medication than never users. Fifth, previous OC users were much more likely than never users to report a history of premenarchial habitation with a man who was not biologically related to them, and there was also a strong trend towards higher rates of such habitation in current OC users compared to never users. The results from the phase two sample of 60 nonusers and 50 OC users indicated group differences on six variables. First, OC users had a more unrestricted sociosexuality score compared to nonusers, with current and previous users scoring similarly. Higher scores for OC users compared to never users reflected a higher number of sexual partners in the past year, a higher number of one-time sexual partners, a higher predicted number of sexual partners in the next five years (when relationship status was controlled), and greater agreement with three unrestricted sexual beliefs. Second, OC users had a much lower left hand 2D:4D than nonusers. While the left 2D:4D of current OC users did not differ from men, both of these latter groups had significantly lower 2D:4D than never users and previous users. Third, consistent with the phase one findings, the OC users again reported an earlier age of menarche. Fourth, OC users had a higher mean positive affect score than nonusers, contrary to the findings in phase one. Fifth, OC users were more likely to report use of illegal recreational drugs than nonusers. Sixth, there were nonsignificant trends towards OC users being younger and having lower BMI and WHR than nonusers. Masculine 2D:4D in Current OC Users The 2D:4D findings suggest that current OC users may have been exposed to more masculine levels of prenatal testosterone than other women. Current OC users may have, on average, been exposed to testosterone levels more similar to those that men were exposed to, and significantly higher than the levels that never users and previous users were exposed to. Thus, OC users may represent a group that is hormonally distinct from previous or never users of OCs. Although reasons for discontinuing OCs were not obtained, the significantly higher left and right hand mean 2D:4D in previous users compared to current users suggests the possibility that previous users stopped taking OCs for a hormonal reason that might reflect an interaction between their prenatal hormone exposure and use of OCs. Some OC side effects, particularly ones more likely to cause discontinuation (e.g., mood change, bleeding irregularities, breast tenderness, weight gain, headache, nausea), could be more common in high 2D:4D women given that they may have had less prenatal testosterone and higher prenatal estrogen exposure. The 2D:4D difference between current and never users is consistent with the group difference in sociosexual orientation (i.e., more unrestricted individuals with lower 2D:4D choosing to take OCs), and with Clark s (2004) finding of a negative relationship between unrestricted sociosexuality and 2D:4D. However, these findings do not fit with our finding of a positive relationship between unrestricted sociosexuality and 2D:4D in free-cycling women (Oinonen & Mazmanian, 2003). Furthermore, differences in sociosexual orientation cannot explain 2D:4D differences between current and previous OC users as these groups did not differ in terms of their SOI scores. We recently found that free-cycling women with more regular and predictable menstrual cycles have higher 2D:4D than women with less predictable cycles (Oinonen & Mazmanian, unpublished). Thus, it is possible that the present finding of a relationship between OC status

14 108 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian and 2D:4D represents a sampling bias. Participant selection criteria may have resulted in a group of OC users with less regular natural cycles due to the fact that only women with regular cycles were represented in the current and previous user groups. Although an irregular menstrual cycle was an exclusion criterion for both groups of women, the OC users likely had less regular cycles prior to taking OCs (possibly related to higher prenatal testosterone exposure), given that some women take OCs to regulate their cycle. Thus, OC users in the current sample may have lower 2D:4D than nonusers partially due to the sampling procedures. However, even if there were a selection bias towards having more women with naturally irregular cycles in the OC user group, women with irregular cycles would generally be more likely, than women with regular cycles, to take OCs in order to regulate their cycles. Thus, such a sampling bias (if present) may only slightly overestimate any naturally occurring differences in natural cycle regularity between OC user and nonuser groups. Furthermore, any sampling bias cannot explain why the current OC users had similar 2D:4D to men and why previous OC users had the most feminine 2D:4D. Based on research suggesting that mean 2D:4D in a given sample is relatively fixed by the 13 th week of fetal development (Garn et al., 1975), and is stable from birth to age 25 (Manning et al., 1998), it is believed that 2D:4D is set at birth. However, no studies have examined 2D:4D before and after OC use. Furthermore, there is evidence that menstrual phase (Deie et al., 2002) and oral contraceptive use (Wojtys et al., 2002) affect joint laxity, and that free testosterone levels differ between OC users and nonusers (Bancroft et al., 1991a). Thus, the possibility that OCs can alter 2D:4D deserves exploration. No previous studies have compared 2D:4D in women of different OC status or controlled for OC use when examining 2D:4D. However, while previous research has indicated ethnic differences in 2D:4D, the overall 2D:4D for women in this Canadian northwestern Ontario university sample (mean of 0.98 for both left and right hands) is most similar to Spanish women; is lower than English women; and is higher than Finnish female children, Zulu South African women, and Jamaican women (Manning et al., 2000; Manning, Martin, et al., 2002). The women s mean 2D:4D is also slightly higher than another published report of 2D:4D in Canadian women (Coolican & Peters, 2003). However, Coolican and Peters sample from a southern Ontario university population may have had a higher proportion of OC users in their sample, as nonusers were over-represented in our sample. The present findings suggest that the relationship between OC status and 2D:4D should be explored further. A More Unrestricted Sociosexual Orientation in OC Users The more unrestricted sociosexual orientation in OC users is consistent with the findings of Bancroft and colleagues (1991b). Taken together with the other differences between groups found here, there are at least two explanations for this finding. The first possible explanation is that unrestricted women (those who have 2D:4D in the high or low extremes of the female range) are more likely to choose to use OCs, and those with low prenatal testosterone exposure (high 2D:4D) are more likely to discontinue use for reasons that may be related to hormonal side effects. This explanation suggests that sociosexuality may be related to hormonal mechanisms that affect 2D:4D (e.g., prenatal hormone exposure), sociosexuality affects the decision to use OCs, and that both sociosexuality and 2D:4D may reflect one or more hormonal factors that interact to cause hormonal differences between OC groups.

15 Hormonal Differences in Oral Contraceptive Users? 109 The second possible explanation for the differences in sociosexuality between the OC user groups is that women taking OCs might experience an alteration in their sociosexual orientation when taking OCs. It may be that use of OCs leads to a more unrestricted sociosexual orientation due to: (a) a decreased fear of pregnancy, and/or (b) a direct biological hormonal effect on sociosexuality. The former explanation might involve small initial increases in unrestricted sexual behaviour when one takes OCs as decreased fear of pregnancy may eliminate an important reason for restricted sexual behaviour. Small increases in unrestricted sexual behaviour would likely be followed by increases in unrestricted beliefs due to the motivation to reduce cognitive dissonance. The latter pharmacological explanation (i.e., OCs alter sociosexuality) also has some support from the body of research indicating that hormones affect women s sexual arousal (Tuiten et al., 2000), sexual desire (e.g., Alexander et al., 1990; Alexander & Sherwin, 1993), perception and response to sexual stimuli (e.g., Krug et al., 1994; 2000; Macrae et al., 2002), sex role identity (Csatho et al., 2003) and sexual orientation (Williams et al., 2000). There are also a number of studies indicating that OCs affect women s partner preferences (e.g., Gangestad & Thornhill, 1998; Krug et al., 1994; Penton-Voak et al., 1999; Wedekind and Furi, 1997). However, it is worth noting that a recent prospective study found that, in women starting OCs, use of OCs over a three-month period was not associated with any consistent changes in the frequency of sexual thoughts or sexual intercourse (Graham et al., 2007). While sociosexual orientation is more likely to affect the decision to use OCs than vice versa, the possibility that OCs affect sociosexual orientation deserves further exploration. OC Users have Earlier Menarche and More Premenarchial Habitation with Unrelated Men Ever users of OCs started menstruating at an earlier age than never users, and previous users were more than twice as likely to have lived in the same house with an unrelated man prior to menarche than never users. Other than one inconsistent finding for age of menarche (Harding et al., 1985), previous research has not examined either age of menarche or male presence in the home as a function of OC group. The first report of an association between age of menarche and the presence or absence of human males in the home appears to have been described by Jones et al. (1972). It appears that only one study has examined the relationship between menarcheal age and habitation with an unrelated man (Oinonen & Mazmanian, 2003). Instead, most researchers have reported the phenomenon as an association between menarcheal age and father absence (e.g., Moffitt et al., 1992). Paternal genetic (e.g., Comings et al., 2002), maternal genetic (e.g., Kim & Smith, 1998), pheromonal (Burger & Gochfeld, 1985; Jones et al., 1972), and stress (e.g., Moffitt et al., 1992) explanations for the relationship have been suggested. Particularly relevant to the finding of earlier menarche in girls who resided with unrelated men is Comings and colleagues (2002) report that an X-linked androgen receptor gene, found in fathers who are more likely to abandon their families, may be passed onto their daughters resulting in early menarche and precocious sexuality. Such a gene might explain the earlier menarche, slightly higher rates of premenarchial habitation with an unrelated man (as their mothers would be more likely to find and live with a new partner), the more unrestricted sociosexual orientation, and the lower 2D:4D in women who currently use OCs.

16 110 Kirsten A. Oinonen, Janelle A. Jarva and Dwight Mazmanian Although it does not account for the high 2D:4D and unrestricted sociosexuality in previous users, the pattern of the findings in current OC users combined with the above findings by Comings and colleagues, provides support for a recent hypothesis that 2D:4D is a proxy for transactivation activity of the androgen receptor (Manning, Bundred et al., 2002). One could argue that the later age of menarche in never users means that these women have been sexually mature for a shorter time period and may not have had as much opportunity to find a partner and start a sexual relationship. There is some support for a positive association between age of menarche and age of first intercourse, although the association may be due to genetics (e.g., Rowe, 2002). In the present sample, there was no difference in the age of menarche between women (age 17 to 30) who were in a relationship (M = 12.64, SD = 1.36, n = 258) and those not in a relationship (M = 12.61, SD = 1.29, n = 217), t (473) = -2.49, p =.80); suggesting that age of menarche did not affect the likelihood of having a partner. This last finding also suggests that the association between age of menarche and age of first intercourse may be due to hormonal factors that are mediated by sociosexual orientation, as opposed to simply being due to sexual maturation. These findings cannot tell us whether the never users have simply not yet had the opportunity to use OCs due to later sexual maturation, or whether the never users are less likely to use them for another hormonal reason (e.g., family history of mood or somatic problems with OC use or a more restricted sociosexual orientation). However, regardless of why the group differences in age of menarche exist, they do exist in this sample, and may indicate subtle hormonal differences between OC user groups sampled from such a population. Also worth noting is the fact that OC users are more likely to be in a relationship than never users. These relationships may be currently providing them with more exposure to male pheromones. This is particularly relevant given recent evidence that exposure to hormones in male sweat affects secretion of luteinizing hormone and alters mood in women (e.g., Preti et al., 2003). Therefore, both premenarchial and postmenarchial exposure to the pheromones of unrelated men may contribute to any hormonal differences between OC users and never users. Higher Rates of Hormonal Disorders in Previous than Never Users Ten percent of previous OC users reported a hormonal medical condition (e.g., a thyroid disorder, polycystic ovary syndrome, ovarian cysts, diabetes), compared to only 1% of the never users. These results may be related to the finding that a group of previous users (which did not include any of the women with hormonal medical conditions) also had the highest 2D:4D. This suggests that their pattern of prenatal hormone exposure may have been quite different than the average woman. The higher rate of hormonal disorders also suggests that previous OC users may comprise a group of women who represent a hormonal extreme, and may be more likely to stop using OCs due to hormonal side effects. That is, previous users may be more sensitive to postnatal effects of hormones. Higher Rates of Medication Use and Illegal Drug Use in OC Users Women who have ever used OCs were more likely to take prescribed and illegal drugs. Both current (22%) and previous users (26%) were more likely to be taking a non-oc medication than never users (10%). OC users were more likely to report illegal drug use than