CSIRO PUBLISHING
Sexual Health, 2014, 11, 406–415 http://dx.doi.org/10.1071/SH14113
First vaginal intercourse and oral sex among a representative sample of Australian adults: the Second Australian Study of Health and Relationships Chris Rissel A,I, Wendy Heywood B, Richard O. de Visser C, Judy M. Simpson D, Andrew E. Grulich E, Paul B. Badcock B,F,G, Anthony M. A. Smith B,H and Juliet Richters E A
Sydney School of Public Health, Charles Perkins Centre (D17), University of Sydney, Sydney, NSW 2006, Australia. B Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia. C School of Psychology, Pevensey 1, University of Sussex, Falmer BN1 9QH, UK. D Sydney School of Public Health, Edward Ford Building (A27), University of Sydney, Sydney, NSW 2006, Australia. E The Kirby Institute, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia. F Centre for Youth Mental Health, University of Melbourne, Orygen Youth Research Centre, 35 Poplar Road, Parkville, Vic. 3052, Australia. G School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia. H Deceased. I Corresponding author. Email: [email protected]
Abstract. Background: Current information about the characteristics of Australian adults’ first vaginal intercourse and contraception or precautions used on that occasion is needed, as well as whether these characteristics have changed between 2001–02 and 2012–13. Methods: Computer-assisted telephone interviews were completed by a representative sample of 20 094 men and women aged 16–69 years. The overall participation rate among eligible people was 66.2%. Respondents indicated their age at first vaginal intercourse and first oral sex. Those who reported vaginal intercourse were asked the age of their partner, their relationship to their partner, the duration of this relationship, and what contraception or precautions (if any) were used. Results: There was a significant decline in the median age of first vaginal intercourse for both men and women among those born between the 1940s and the 1960s, but no further decline since. There has also been a significant increase in the use of protection at first vaginal intercourse, from less than 20% of men and women in the 1950s to over 90% in the 2000s. For men and women, first vaginal sex before age 16 years was significantly associated with a greater number of lifetime and recent sexual partners, and a greater likelihood of having had a sexually transmitted infection. Conclusion: Given the earlier age at first vaginal intercourse, sex education should begin earlier so that all young people have information about contraception and disease prevention before they begin their sexual careers. Received 15 June 2014, accepted 5 August 2014, published online 7 November 2014 Introduction National sexual health surveys have documented a fall in the median age at first sexual intercourse in the last 50 years, which has been more marked among women.1–3 In most countries, men report earlier ages at first intercourse than do women; the exceptions being some Scandinavian countries such as Denmark and Norway4 and some Asian countries.1 Traditionally, age at sexual initiation has been a public health concern because earlier initiation may be more likely to be non-consensual,5 less likely to be protected against unplanned pregnancy and infection, and associated with larger lifetime numbers of sexual partners and greater sexual Journal compilation CSIRO 2014
diversity.6–8 Sexual identity influences age of first vaginal sex.7 Understanding the generational timing of first vaginal intercourse can also contribute to planning for adolescent sexual health services. Generally, women report that their partner at first intercourse was older than they were at the time; and men are more likely to report that their partner was of the same age or younger than they were.9 First intercourse with a relatively older or younger partner can be associated with adverse circumstances such as condoms and other reliable contraception being less likely to be used.10 In the first Australian Study of Health and Relationships (ASHR1), the age of first vaginal sex was examined with respect www.publish.csiro.au/journals/sh
First vaginal intercourse and oral sex
to the decade in which people were born.7 Half the men born between 1941 and 1950 had had vaginal intercourse by age 18 years and this median age of first vaginal intercourse declined to 16 years for men born between 1981 and 1986. For women, the median age at first vaginal intercourse declined from 19 years for women born between 1941 and 1950 to 16 years for women born between 1981 and 1986. The age at first experience of oral sex decreased even more steeply, typically occurring around the time of first vaginal intercourse for those born in the 1980s rather than some years afterward. The age of first homosexual experience was older than the age of first heterosexual experience.11 Consistent with such findings, representative studies of Australian secondary students suggest that for the last decade or two, the majority (70%) of Year 10 (aged 15–16 years) and Year 12 (aged 17–18 years) students (88%) have been sexually active in some way. Of those surveyed (in 2008), over onequarter of Year 10 students and approximately half of Year 12 students had experienced vaginal intercourse and a further one-third of Year 10 students and over half of Year 12 students had only experienced oral sex.12,13 Results also suggested an increase in sexual activity among young people over time. For example, there was a significant increase in the proportion of students experiencing vaginal intercourse between 1992 and 2002 (35% vs 42%);14 and between 1997 and 2008, the proportion of sexually active students reporting sex with three or more people rose from 16% to 30%.14 There is conflicting information on whether there is a continued global decrease in the age of first sex. For example, the proportion of 16- to 24-year-olds in the British National Study of Sexual Attitudes and Lifestyles (Natsal-2 and -3) survey respondents who had had heterosexual vaginal sex before age 16 years increased slightly from 27% in 200115 to 29% in 2010–12.16 However, US data suggest that the percentage of youth aged 15–19 years who have had sexual intercourse has gone down since the mid 1990s.17 Contraceptive use at the time of first sex had increased in Australia from 1950 to 2001,7 and in the US, it has increased since 1988, from 67% among women to 78% in 2006–10, and from 71% to 85% among men. Condom use at the time of first sex also increased, from 50% in 1988 to 68% in 2006–10 among women, and from 55% in 1988 to 80% in 2006–10 among US men.17 The aim of this paper is to describe the characteristics associated with first vaginal intercourse, explore if the age of first vaginal intercourse has changed in Australia since 2002, and to determine if there has been a change in contraceptive use at this event. Methods The methodology used in the Second Australian Study of Health and Relationships (ASHR2) is described in detail elsewhere in this issue.18 Briefly, between October 2012 and November 2013, computer-assisted telephone interviews were completed by a representative sample of 20 094 Australian residents aged 16–69 years from all states and territories. Ethical approval was obtained from the researchers’ host universities. Respondents were selected using dual-frame modified random-digit dialling (RDD), combining directory-assisted, landline-based RDD with
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407
RDD of mobile telephones. The overall participation rate among eligible people was 66.2%. To maximise the number of interviews with people who had engaged in less-common and/or more-risky behaviours, all respondents who had had no sexual partners in the previous year, who had had more than one partner in the previous year, and/or who reported homosexual experience completed a long form of the survey instrument, which collected detailed data on their sexual attitudes, relationships and behaviours. Of respondents who reported having had one partner in the previous year and no homosexual experience, 20% were randomly selected to complete the long-form interview and the other 80% completed a shortform interview. As a consequence, 8577 completed the longform interview, and 11 517 completed the short-form interview. Answers to questions that occurred only in the long-form interview are reported after weighting to reflect the sample as a whole. All respondents indicated their age at first vaginal intercourse. Those who reported vaginal intercourse were also asked the age of their partner, their relationship to their partner, the duration of the relationship before first vaginal intercourse, and what contraception (if any) was used. The detail collected about the type of contraception used was limited to condom, other method (e.g. the pill), withdrawal or ‘safe period’. Respondents also indicated their age when they first had oral sex (see Boxes 1, 2). Data for age at first vaginal intercourse were used to create a new dichotomous variable that identified men and women who first had vaginal intercourse before the age of 16 years. Correlates of the main outcomes examined in this paper included a range of demographic characteristics, which were recoded to facilitate analysis. Respondents’ ages were recoded into six groups: 16–19, 20–29, 30–39, 40–49, 50–59 and 60–69 years. Language spoken at home was recoded
Box 1. Ascertainment of first sexual experiences of men
The next questions are about your first sexual experiences. How old were you when you first had vaginal intercourse? (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.) How old was she? How long had you known her before you had sex for the first time? What was your relationship to her? What contraception or precautions did you or she use that first time, if any? How old were you when you first had oral sex with a female? That’s with your penis in her mouth, or your mouth on her vaginal area. (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.)
408
Sexual Health
Box 2.
Ascertainment of first sexual experiences of women
The next questions are about your first sexual experiences. How old were you when you first had vaginal intercourse? (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.) How old was he? How long had you known him before you had sex for the first time? Interviewer prompts with Known counts from when first met in person. What was your relationship to him? What contraception or precautions did you or he use that first time, if any? How old were you when you first had oral sex with a male? That’s with his penis in your mouth, or his mouth on your vaginal area. (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.)
as English or a language other than English. Sexual identity (in answer to the question ‘Do you think of yourself as . . .’) was coded as heterosexual, homosexual, or bisexual; too few respondents stated that they were ‘queer’, ‘other’, or ‘undecided’ to allow analysis of these groups. Respondents’ reported highest completed level of education was recoded to distinguish between those who had not (yet) completed secondary school, those who had completed secondary school, and those who had completed post-secondary education. Respondents’ postcodes were used with the Accessibility/Remoteness Index of Australia (ARIA)19 to determine whether respondents lived in a major city, a regional area, or a remote area (i.e. areas with relatively unrestricted, restricted, and very restricted access to goods, services and opportunities for social interaction, respectively). To approximate the gross annual household income quintiles reported by the Australian Bureau of Statistics for 2009–10,20 respondents’ reported annual income was grouped into five categories: less than $28 000, $28 001–$52 000, $52 001– $83 000, $83 001–$125 000 and more than $125 000. Respondents’ reported occupations were coded into the nine major categories of the Australian Standard Classification of Occupations,21 and then recoded to distinguish between managerial/professional occupations, white-collar occupations and blue-collar occupations. Associations between early sexual debut and various sexual health outcomes were also examined, including number of lifetime partners and partners in the last 12 months, having ever had oral or anal sex, having ever had homosexual sexual experience, having ever had a sexually transmitted infection, and having received any sex education at school. Finally, the early sexual debut results were compared with those of ASHR1 to identify significant changes over time.
C. Rissel et al.
Data were weighted to adjust for the probability of each respondent being selected for a landline or mobile phone interview, a long-form interview and the probability of selection (for landline participants) given the number of eligible adults in the household. Data were then weighted to match the Australian population on the basis of age, gender, area of residence (i.e. state by ARIA category) and telephone ownership (i.e. mobile telephone only vs other), resulting in an adjusted sample of 10 056 men and 10 038 women (total 20 094). The data were thus weighted to account for the specifics of our sample design and the fact that particular types of people were slightly over- or under-represented. Therefore, the data presented describe the Australian population aged 16–69 years, subject to the biases noted elsewhere in this issue.18 Weighted data were analysed using the survey estimation commands in Stata Version 11.2 (StatCorp LP, College Station, TX, USA).22 Data were analysed using univariate logistic regression for dichotomous outcomes, including comparisons of ASHR1 and ASHR2. To account for censoring (i.e. that for some respondents, events had not yet occurred), analysis of age at first vaginal intercourse was conducted using Cox proportional hazards modelling, and median ages at first vaginal intercourse were obtained from a Kaplan–Meier life table. In these analyses, age was treated as a continuous variable. Percentages are presented in this article without standard errors or 95% confidence intervals. This decision was made to maximise both readability and brevity, and is in keeping with the style of other studies of a similar scope and intent.23–25 Further information about the precision of estimates is found elsewhere in this issue.18 Results Most respondents (96.7% of men and 96.9% of women) reported some heterosexual experience. First vaginal intercourse Nearly all respondents had engaged in vaginal intercourse, and a similar proportion of men and women had had vaginal intercourse (men, 94.1%; women, 94.2%; P = 0.71). Table 1 displays data relating to age at first vaginal intercourse. The ages at which respondents first had vaginal intercourse ranged from self-reported 1 to 51 years. Women (median 18 years) did not report significantly older ages at first vaginal intercourse than men [median 17 years, hazard ratio (HR): 0.99, P = 0.41]. The age at which respondents first had vaginal intercourse was significantly related to sexual identity. There was no difference in age at first vaginal sex for heterosexually identified men (median 17 years) and bisexually identified men (median 17 years, HR: 1.06, P = 0.62), but homosexually identified men reported significantly later ages at first vaginal intercourse (median not calculated due to high levels of censoring, HR: 0.20, P < 0.001). Women who identified as lesbian or homosexual reported significantly later ages at first vaginal intercourse (median 19 years, HR: 0.37, P < 0.001) than women who identified as heterosexual (median 18 years), but bisexual women reported significantly earlier ages at first vaginal intercourse (median 17 years, HR: 1.54, P < 0.001).
First vaginal intercourse and oral sex
Table 1.
409
Age at first vaginal intercourse with respect to current sexual identity among men and women Unless indicated otherwise, data show percentages for each category
Age at first vaginal intercourse (years)
Sexual identity (%) Heterosexual (n = 9725)
15 16 17 18 19 20 21 or older Never MeanB 95% CI Median Minimum Maximum
Sexual Health
17.6 16.1 18.2 15.7 7.8 5.4 15.2 2.3 17.9 17.8–18.0 17 1 50
Men Homosexual (n = 189) 16.9 11.5 14.0 6.0 10.4 8.5 21.3 10.9 18.4 17.7–19.2 18 12 30
Bisexual (n = 126)
TotalA (n = 9962)
Heterosexual (n = 9669)
27.6 13.1 19.5 11.3 6.2 2.2 11.6 7.5 17.0 16.3–17.8 17 7 35
17.7 16.0 18.1 15.6 7.8 5.4 15.2 2.4 17.9 17.8–18.0 17 1 50
13.8 17.2 17.6 16.3 8.9 5.7 15.3 2.8 18.0 18.0–18.1 18 1 51
Women Homosexual Bisexual (n = 122) (n = 224) 23.2 8.6 11.9 14.7 7.3 5.4 16.5 7.2 17.6 16.5–18.8 19 5 34
TotalA (n = 10 128)
25.4 22.9 19.4 13.7 2.3 1.8 5.9 2.9 16.4 16.0–16.9 17 12 31
14.2 17.3 17.6 16.3 8.7 5.6 15.1 2.8 18.0 17.9–18.1 18 1 51
Includes ‘Other’ and ‘Undecided’. For those who have had vaginal intercourse.
A B
20 Men
Median age (years)
Women 19
18
17
7
4 95 19
–9 90
19
–9
9
4
–8 85
19
–8
9 19
80
4
–7
19
75
9
–7
19
70
4
–6 65
19
–6 60
19
19
55
–5
9
4
9
–5
–4
50 19
45
42
19
–4
4
16
19
Heterosexually identified women reported a significantly older age at first vaginal intercourse than heterosexually identified men (HR: 0.96, P = 0.01). However, the ages at which homosexually identified and bisexually identified women first had vaginal intercourse were significantly younger than homosexually identified men (HR: 1.77, P = 0.001) and bisexually identified men (HR: 1.30, P = 0.05), respectively. The data in Fig. 1 show a decrease from the 1950s to the 1970s (i.e. when respondents were 17–19 years old) in the reported median age at which respondents first had vaginal intercourse, and has been mostly stable at age 17 years for both men and women since the mid 1980s. Among both men (P = 0.003) and women (P = 0.001), modelling showed that overall increasing age was associated with a decrease in age of first vaginal intercourse. Table 2 displays information about respondents’ first experiences of vaginal intercourse. There was a significant association between gender and the age difference between the respondent and his/her partner (P < 0.001). Men were less likely to report that they were younger than their partner. Men and women reported different patterns of relationships with their partners at first vaginal intercourse (P < 0.001). Men were more likely to report that they first had vaginal intercourse with a casual partner, whereas women were more likely to report that their partner was their husband, fiancé or steady partner. Only men reported that their first experience of vaginal intercourse was with a sex worker, although this was a very small proportion of men (1%). Men also reported that they had known their first vaginal-intercourse partner for a shorter time than had women (P < 0.001). Three-quarters of respondents reported that they used some form of protection against pregnancy or sexually transmissible infections (STIs) the first time they had vaginal intercourse. There was a significant gender difference in reports of protection used during the first experience of vaginal intercourse (P < 0.001). Women were less likely to report that no
Year of birth Fig. 1. Median age at first vaginal intercourse by year of birth and sex.
protection was used and more likely to report that other forms of contraception apart from a condom, such as the oral contraceptive pill, were used. Figure 2 shows that, over time, more people reported use of some form of protection on the first occasion of vaginal intercourse; from 13.6% of men and 17.2% of women who first had sex in the 1950s to 91.5% of men and 97.4% of women who first had sex in the 2010s. Furthermore, condom use during the first experience of vaginal intercourse has increased over time, and condom use has come to account for a larger proportion of contraceptive use during the first vaginal intercourse. For example, 81.9% of men and 80.2% of women who first had vaginal intercourse after 2010 used a condom. The data in Table 3 reveal the ages at which respondents first had oral sex with a partner of the other sex; no distinction was made between fellatio and cunnilingus. Experience of oral sex was reported by 85.8% of men and 80.1% of women, with men
410
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C. Rissel et al.
Table 2.
Context of the first experience of vaginal intercourse for men and women for the 94.4% of men and 94.2% of women who reported experience of vaginal intercourse Unless indicated otherwise, data show percentages for each category
Context
Men (n = 9962)
Women (n = 10 128)
OR (95% CI)A
4.1 20.6 45.2 24.9 0.9
10.3 56.0 25.2 3.7 0.2
0.92 (0.80–1.05) 1 0.21 (0.19–0.22) 0.05 (0.05–0.06) 0.06 (0.03–0.10)
5.2 1.4 0.5 51.8 39.3 1.0 0.2 0.6
8.2 3.4 1.0 66.1 19.2 0.0 0.1 1.1
1.23 (1.09–1.39) 1.92 (1.56–2.37) 1.50 (1.03–2.18) 1 0.38 (0.36–0.41) –B –B –B
7.5 4.1 9.8 37.1 40.4 0.0 1.0
1.9 1.9 5.4 39.6 49.9
Sexual Health, 2014, 11, 406–415 http://dx.doi.org/10.1071/SH14113
First vaginal intercourse and oral sex among a representative sample of Australian adults: the Second Australian Study of Health and Relationships Chris Rissel A,I, Wendy Heywood B, Richard O. de Visser C, Judy M. Simpson D, Andrew E. Grulich E, Paul B. Badcock B,F,G, Anthony M. A. Smith B,H and Juliet Richters E A
Sydney School of Public Health, Charles Perkins Centre (D17), University of Sydney, Sydney, NSW 2006, Australia. B Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia. C School of Psychology, Pevensey 1, University of Sussex, Falmer BN1 9QH, UK. D Sydney School of Public Health, Edward Ford Building (A27), University of Sydney, Sydney, NSW 2006, Australia. E The Kirby Institute, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia. F Centre for Youth Mental Health, University of Melbourne, Orygen Youth Research Centre, 35 Poplar Road, Parkville, Vic. 3052, Australia. G School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia. H Deceased. I Corresponding author. Email: [email protected]
Abstract. Background: Current information about the characteristics of Australian adults’ first vaginal intercourse and contraception or precautions used on that occasion is needed, as well as whether these characteristics have changed between 2001–02 and 2012–13. Methods: Computer-assisted telephone interviews were completed by a representative sample of 20 094 men and women aged 16–69 years. The overall participation rate among eligible people was 66.2%. Respondents indicated their age at first vaginal intercourse and first oral sex. Those who reported vaginal intercourse were asked the age of their partner, their relationship to their partner, the duration of this relationship, and what contraception or precautions (if any) were used. Results: There was a significant decline in the median age of first vaginal intercourse for both men and women among those born between the 1940s and the 1960s, but no further decline since. There has also been a significant increase in the use of protection at first vaginal intercourse, from less than 20% of men and women in the 1950s to over 90% in the 2000s. For men and women, first vaginal sex before age 16 years was significantly associated with a greater number of lifetime and recent sexual partners, and a greater likelihood of having had a sexually transmitted infection. Conclusion: Given the earlier age at first vaginal intercourse, sex education should begin earlier so that all young people have information about contraception and disease prevention before they begin their sexual careers. Received 15 June 2014, accepted 5 August 2014, published online 7 November 2014 Introduction National sexual health surveys have documented a fall in the median age at first sexual intercourse in the last 50 years, which has been more marked among women.1–3 In most countries, men report earlier ages at first intercourse than do women; the exceptions being some Scandinavian countries such as Denmark and Norway4 and some Asian countries.1 Traditionally, age at sexual initiation has been a public health concern because earlier initiation may be more likely to be non-consensual,5 less likely to be protected against unplanned pregnancy and infection, and associated with larger lifetime numbers of sexual partners and greater sexual Journal compilation CSIRO 2014
diversity.6–8 Sexual identity influences age of first vaginal sex.7 Understanding the generational timing of first vaginal intercourse can also contribute to planning for adolescent sexual health services. Generally, women report that their partner at first intercourse was older than they were at the time; and men are more likely to report that their partner was of the same age or younger than they were.9 First intercourse with a relatively older or younger partner can be associated with adverse circumstances such as condoms and other reliable contraception being less likely to be used.10 In the first Australian Study of Health and Relationships (ASHR1), the age of first vaginal sex was examined with respect www.publish.csiro.au/journals/sh
First vaginal intercourse and oral sex
to the decade in which people were born.7 Half the men born between 1941 and 1950 had had vaginal intercourse by age 18 years and this median age of first vaginal intercourse declined to 16 years for men born between 1981 and 1986. For women, the median age at first vaginal intercourse declined from 19 years for women born between 1941 and 1950 to 16 years for women born between 1981 and 1986. The age at first experience of oral sex decreased even more steeply, typically occurring around the time of first vaginal intercourse for those born in the 1980s rather than some years afterward. The age of first homosexual experience was older than the age of first heterosexual experience.11 Consistent with such findings, representative studies of Australian secondary students suggest that for the last decade or two, the majority (70%) of Year 10 (aged 15–16 years) and Year 12 (aged 17–18 years) students (88%) have been sexually active in some way. Of those surveyed (in 2008), over onequarter of Year 10 students and approximately half of Year 12 students had experienced vaginal intercourse and a further one-third of Year 10 students and over half of Year 12 students had only experienced oral sex.12,13 Results also suggested an increase in sexual activity among young people over time. For example, there was a significant increase in the proportion of students experiencing vaginal intercourse between 1992 and 2002 (35% vs 42%);14 and between 1997 and 2008, the proportion of sexually active students reporting sex with three or more people rose from 16% to 30%.14 There is conflicting information on whether there is a continued global decrease in the age of first sex. For example, the proportion of 16- to 24-year-olds in the British National Study of Sexual Attitudes and Lifestyles (Natsal-2 and -3) survey respondents who had had heterosexual vaginal sex before age 16 years increased slightly from 27% in 200115 to 29% in 2010–12.16 However, US data suggest that the percentage of youth aged 15–19 years who have had sexual intercourse has gone down since the mid 1990s.17 Contraceptive use at the time of first sex had increased in Australia from 1950 to 2001,7 and in the US, it has increased since 1988, from 67% among women to 78% in 2006–10, and from 71% to 85% among men. Condom use at the time of first sex also increased, from 50% in 1988 to 68% in 2006–10 among women, and from 55% in 1988 to 80% in 2006–10 among US men.17 The aim of this paper is to describe the characteristics associated with first vaginal intercourse, explore if the age of first vaginal intercourse has changed in Australia since 2002, and to determine if there has been a change in contraceptive use at this event. Methods The methodology used in the Second Australian Study of Health and Relationships (ASHR2) is described in detail elsewhere in this issue.18 Briefly, between October 2012 and November 2013, computer-assisted telephone interviews were completed by a representative sample of 20 094 Australian residents aged 16–69 years from all states and territories. Ethical approval was obtained from the researchers’ host universities. Respondents were selected using dual-frame modified random-digit dialling (RDD), combining directory-assisted, landline-based RDD with
Sexual Health
407
RDD of mobile telephones. The overall participation rate among eligible people was 66.2%. To maximise the number of interviews with people who had engaged in less-common and/or more-risky behaviours, all respondents who had had no sexual partners in the previous year, who had had more than one partner in the previous year, and/or who reported homosexual experience completed a long form of the survey instrument, which collected detailed data on their sexual attitudes, relationships and behaviours. Of respondents who reported having had one partner in the previous year and no homosexual experience, 20% were randomly selected to complete the long-form interview and the other 80% completed a shortform interview. As a consequence, 8577 completed the longform interview, and 11 517 completed the short-form interview. Answers to questions that occurred only in the long-form interview are reported after weighting to reflect the sample as a whole. All respondents indicated their age at first vaginal intercourse. Those who reported vaginal intercourse were also asked the age of their partner, their relationship to their partner, the duration of the relationship before first vaginal intercourse, and what contraception (if any) was used. The detail collected about the type of contraception used was limited to condom, other method (e.g. the pill), withdrawal or ‘safe period’. Respondents also indicated their age when they first had oral sex (see Boxes 1, 2). Data for age at first vaginal intercourse were used to create a new dichotomous variable that identified men and women who first had vaginal intercourse before the age of 16 years. Correlates of the main outcomes examined in this paper included a range of demographic characteristics, which were recoded to facilitate analysis. Respondents’ ages were recoded into six groups: 16–19, 20–29, 30–39, 40–49, 50–59 and 60–69 years. Language spoken at home was recoded
Box 1. Ascertainment of first sexual experiences of men
The next questions are about your first sexual experiences. How old were you when you first had vaginal intercourse? (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.) How old was she? How long had you known her before you had sex for the first time? What was your relationship to her? What contraception or precautions did you or she use that first time, if any? How old were you when you first had oral sex with a female? That’s with your penis in her mouth, or your mouth on her vaginal area. (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.)
408
Sexual Health
Box 2.
Ascertainment of first sexual experiences of women
The next questions are about your first sexual experiences. How old were you when you first had vaginal intercourse? (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.) How old was he? How long had you known him before you had sex for the first time? Interviewer prompts with Known counts from when first met in person. What was your relationship to him? What contraception or precautions did you or he use that first time, if any? How old were you when you first had oral sex with a male? That’s with his penis in your mouth, or his mouth on your vaginal area. (If respondent asks re sexual contact with adults as a child, interviewer says: You don’t need to count anything that happened when you were very young.)
as English or a language other than English. Sexual identity (in answer to the question ‘Do you think of yourself as . . .’) was coded as heterosexual, homosexual, or bisexual; too few respondents stated that they were ‘queer’, ‘other’, or ‘undecided’ to allow analysis of these groups. Respondents’ reported highest completed level of education was recoded to distinguish between those who had not (yet) completed secondary school, those who had completed secondary school, and those who had completed post-secondary education. Respondents’ postcodes were used with the Accessibility/Remoteness Index of Australia (ARIA)19 to determine whether respondents lived in a major city, a regional area, or a remote area (i.e. areas with relatively unrestricted, restricted, and very restricted access to goods, services and opportunities for social interaction, respectively). To approximate the gross annual household income quintiles reported by the Australian Bureau of Statistics for 2009–10,20 respondents’ reported annual income was grouped into five categories: less than $28 000, $28 001–$52 000, $52 001– $83 000, $83 001–$125 000 and more than $125 000. Respondents’ reported occupations were coded into the nine major categories of the Australian Standard Classification of Occupations,21 and then recoded to distinguish between managerial/professional occupations, white-collar occupations and blue-collar occupations. Associations between early sexual debut and various sexual health outcomes were also examined, including number of lifetime partners and partners in the last 12 months, having ever had oral or anal sex, having ever had homosexual sexual experience, having ever had a sexually transmitted infection, and having received any sex education at school. Finally, the early sexual debut results were compared with those of ASHR1 to identify significant changes over time.
C. Rissel et al.
Data were weighted to adjust for the probability of each respondent being selected for a landline or mobile phone interview, a long-form interview and the probability of selection (for landline participants) given the number of eligible adults in the household. Data were then weighted to match the Australian population on the basis of age, gender, area of residence (i.e. state by ARIA category) and telephone ownership (i.e. mobile telephone only vs other), resulting in an adjusted sample of 10 056 men and 10 038 women (total 20 094). The data were thus weighted to account for the specifics of our sample design and the fact that particular types of people were slightly over- or under-represented. Therefore, the data presented describe the Australian population aged 16–69 years, subject to the biases noted elsewhere in this issue.18 Weighted data were analysed using the survey estimation commands in Stata Version 11.2 (StatCorp LP, College Station, TX, USA).22 Data were analysed using univariate logistic regression for dichotomous outcomes, including comparisons of ASHR1 and ASHR2. To account for censoring (i.e. that for some respondents, events had not yet occurred), analysis of age at first vaginal intercourse was conducted using Cox proportional hazards modelling, and median ages at first vaginal intercourse were obtained from a Kaplan–Meier life table. In these analyses, age was treated as a continuous variable. Percentages are presented in this article without standard errors or 95% confidence intervals. This decision was made to maximise both readability and brevity, and is in keeping with the style of other studies of a similar scope and intent.23–25 Further information about the precision of estimates is found elsewhere in this issue.18 Results Most respondents (96.7% of men and 96.9% of women) reported some heterosexual experience. First vaginal intercourse Nearly all respondents had engaged in vaginal intercourse, and a similar proportion of men and women had had vaginal intercourse (men, 94.1%; women, 94.2%; P = 0.71). Table 1 displays data relating to age at first vaginal intercourse. The ages at which respondents first had vaginal intercourse ranged from self-reported 1 to 51 years. Women (median 18 years) did not report significantly older ages at first vaginal intercourse than men [median 17 years, hazard ratio (HR): 0.99, P = 0.41]. The age at which respondents first had vaginal intercourse was significantly related to sexual identity. There was no difference in age at first vaginal sex for heterosexually identified men (median 17 years) and bisexually identified men (median 17 years, HR: 1.06, P = 0.62), but homosexually identified men reported significantly later ages at first vaginal intercourse (median not calculated due to high levels of censoring, HR: 0.20, P < 0.001). Women who identified as lesbian or homosexual reported significantly later ages at first vaginal intercourse (median 19 years, HR: 0.37, P < 0.001) than women who identified as heterosexual (median 18 years), but bisexual women reported significantly earlier ages at first vaginal intercourse (median 17 years, HR: 1.54, P < 0.001).
First vaginal intercourse and oral sex
Table 1.
409
Age at first vaginal intercourse with respect to current sexual identity among men and women Unless indicated otherwise, data show percentages for each category
Age at first vaginal intercourse (years)
Sexual identity (%) Heterosexual (n = 9725)
15 16 17 18 19 20 21 or older Never MeanB 95% CI Median Minimum Maximum
Sexual Health
17.6 16.1 18.2 15.7 7.8 5.4 15.2 2.3 17.9 17.8–18.0 17 1 50
Men Homosexual (n = 189) 16.9 11.5 14.0 6.0 10.4 8.5 21.3 10.9 18.4 17.7–19.2 18 12 30
Bisexual (n = 126)
TotalA (n = 9962)
Heterosexual (n = 9669)
27.6 13.1 19.5 11.3 6.2 2.2 11.6 7.5 17.0 16.3–17.8 17 7 35
17.7 16.0 18.1 15.6 7.8 5.4 15.2 2.4 17.9 17.8–18.0 17 1 50
13.8 17.2 17.6 16.3 8.9 5.7 15.3 2.8 18.0 18.0–18.1 18 1 51
Women Homosexual Bisexual (n = 122) (n = 224) 23.2 8.6 11.9 14.7 7.3 5.4 16.5 7.2 17.6 16.5–18.8 19 5 34
TotalA (n = 10 128)
25.4 22.9 19.4 13.7 2.3 1.8 5.9 2.9 16.4 16.0–16.9 17 12 31
14.2 17.3 17.6 16.3 8.7 5.6 15.1 2.8 18.0 17.9–18.1 18 1 51
Includes ‘Other’ and ‘Undecided’. For those who have had vaginal intercourse.
A B
20 Men
Median age (years)
Women 19
18
17
7
4 95 19
–9 90
19
–9
9
4
–8 85
19
–8
9 19
80
4
–7
19
75
9
–7
19
70
4
–6 65
19
–6 60
19
19
55
–5
9
4
9
–5
–4
50 19
45
42
19
–4
4
16
19
Heterosexually identified women reported a significantly older age at first vaginal intercourse than heterosexually identified men (HR: 0.96, P = 0.01). However, the ages at which homosexually identified and bisexually identified women first had vaginal intercourse were significantly younger than homosexually identified men (HR: 1.77, P = 0.001) and bisexually identified men (HR: 1.30, P = 0.05), respectively. The data in Fig. 1 show a decrease from the 1950s to the 1970s (i.e. when respondents were 17–19 years old) in the reported median age at which respondents first had vaginal intercourse, and has been mostly stable at age 17 years for both men and women since the mid 1980s. Among both men (P = 0.003) and women (P = 0.001), modelling showed that overall increasing age was associated with a decrease in age of first vaginal intercourse. Table 2 displays information about respondents’ first experiences of vaginal intercourse. There was a significant association between gender and the age difference between the respondent and his/her partner (P < 0.001). Men were less likely to report that they were younger than their partner. Men and women reported different patterns of relationships with their partners at first vaginal intercourse (P < 0.001). Men were more likely to report that they first had vaginal intercourse with a casual partner, whereas women were more likely to report that their partner was their husband, fiancé or steady partner. Only men reported that their first experience of vaginal intercourse was with a sex worker, although this was a very small proportion of men (1%). Men also reported that they had known their first vaginal-intercourse partner for a shorter time than had women (P < 0.001). Three-quarters of respondents reported that they used some form of protection against pregnancy or sexually transmissible infections (STIs) the first time they had vaginal intercourse. There was a significant gender difference in reports of protection used during the first experience of vaginal intercourse (P < 0.001). Women were less likely to report that no
Year of birth Fig. 1. Median age at first vaginal intercourse by year of birth and sex.
protection was used and more likely to report that other forms of contraception apart from a condom, such as the oral contraceptive pill, were used. Figure 2 shows that, over time, more people reported use of some form of protection on the first occasion of vaginal intercourse; from 13.6% of men and 17.2% of women who first had sex in the 1950s to 91.5% of men and 97.4% of women who first had sex in the 2010s. Furthermore, condom use during the first experience of vaginal intercourse has increased over time, and condom use has come to account for a larger proportion of contraceptive use during the first vaginal intercourse. For example, 81.9% of men and 80.2% of women who first had vaginal intercourse after 2010 used a condom. The data in Table 3 reveal the ages at which respondents first had oral sex with a partner of the other sex; no distinction was made between fellatio and cunnilingus. Experience of oral sex was reported by 85.8% of men and 80.1% of women, with men
410
Sexual Health
C. Rissel et al.
Table 2.
Context of the first experience of vaginal intercourse for men and women for the 94.4% of men and 94.2% of women who reported experience of vaginal intercourse Unless indicated otherwise, data show percentages for each category
Context
Men (n = 9962)
Women (n = 10 128)
OR (95% CI)A
4.1 20.6 45.2 24.9 0.9
10.3 56.0 25.2 3.7 0.2
0.92 (0.80–1.05) 1 0.21 (0.19–0.22) 0.05 (0.05–0.06) 0.06 (0.03–0.10)
5.2 1.4 0.5 51.8 39.3 1.0 0.2 0.6
8.2 3.4 1.0 66.1 19.2 0.0 0.1 1.1
1.23 (1.09–1.39) 1.92 (1.56–2.37) 1.50 (1.03–2.18) 1 0.38 (0.36–0.41) –B –B –B
7.5 4.1 9.8 37.1 40.4 0.0 1.0
1.9 1.9 5.4 39.6 49.9
