Sexual Timetables for Oral-Genital, Vaginal, and Anal Intercourse: Sociodemographic Comparisons in a Nationally Representative Sample of Adolescents

Abstract

Objectives. We documented the prevalence and relative timing of oral-genital, vaginal, and anal intercourse during adolescence and examined whether these timetables varied by sociodemographic factors.

Methods. We used data from almost 14 000 Wave IV respondents to the National Longitudinal Study of Adolescent Health to generate prevalence estimates for adolescents who reached age 18 years by 2001 and logistic and ordinary least squares regression to examine sociodemographic correlates of sexual patterns.

Results. One in 5 adolescents did not engage in any of these sexual behaviors by age 18 years. More than two thirds reported vaginal or oral-genital sexual activity, but only about half experienced both. One in 10 reported anal intercourse experience. A third initiated 2 or more behaviors within a 1-year period. In longer timetables, vaginal intercourse was more often initiated first. Most sociodemographic characteristics examined were uniquely associated with prevalence and sexual timing.

Conclusions. Diversity in patterns of sexual initiation occurring in the 1990s underscores the ongoing need for comprehensive and nuanced examinations of adolescent sexual trajectories and their implications for sexual health in more recent cohorts.

Sexual behavior patterns have evolved significantly since the “first sexual revolution” of the 1920s.¹ Fewer than 10% of individuals born early in the 20th century had sex by age 18 years, compared with more than 50% of persons born between 1968 and 1973.² Of individuals 15 to 44 years old in 2002, 75% had had premarital vaginal intercourse by age 20 years³; almost 90% of individuals 18 to 27 years old in 2001 had had premarital vaginal intercourse.⁴

Most adolescent sexuality research focuses exclusively on vaginal intercourse. Two cross-sectional US national surveys routinely measure vaginal intercourse in adolescent samples. Estimates from the Centers for Disease Control and Prevention’s 2009 Youth Risk Behavior Survey indicate that approximately 60% of male and 65% of female high-school seniors have had vaginal intercourse.⁵ Similarly, in the 2006 to 2008 National Survey of Family Growth (NSFG), 66% of men and 62% of women aged 18 and 19 years had had vaginal intercourse.⁶

By contrast, estimates of adolescent oral-genital and anal intercourse experience vary widely, probably because most, except NSFG figures, are based on smaller community samples.^7–10 During the 1980s and 1990s, estimates of adolescent oral-genital sexual activity ranged from 35% to 66%. In the 2006 to 2008 NSFG, 70% of men and 63% of women aged 18 to 19 reported oral-genital sexual activity.⁶ Community sample prevalence estimates of adolescent anal intercourse range from 20% to 32%.¹⁰ Recent NSFG data indicate that almost 17% of men and 15% of women aged 18 to 19 years have ever had anal intercourse.⁶ The Youth Risk Behavior Survey does not ask about oral-genital or anal intercourse.

The order of initiating oral-genital and vaginal intercourse is of interest because initiating oral-genital sexual activity first, which carries lower risk of sexually transmitted diseases (STDs) than does vaginal or anal intercourse, could substitute for vaginal and anal intercourse, postpone their onset, or hasten the transition to coital or anal experience. Community sample estimates of initiating oral-genital intercourse first range from 14% to 50%.^7–9,11,12 Some analyses indicate that “vaginal virgins” are less likely to have had oral-genital intercourse than are “vaginal nonvirgins,” implying that vaginal intercourse typically occurs first.^10,13,14 However, about half of male and female respondents aged 15 to 24 reported that they had oral-genital before vaginal intercourse in the 2006 to 2008 NSFG data.⁶ The NSFG does not measure the amount of time separating oral-genital and vaginal initiation. There has been less investigation of anal intercourse, but given its low prevalence (10% of respondents aged 15–19 years in the 2006–2008 NSFG),⁶ if anal intercourse is initiated during adolescence, it will typically occur last.

Timing of first sexual experience may have implications for the sexual sequence and pace that follow.¹⁴ There has been extensive research on the timing of first vaginal intercourse in particular. In the United States, the average age at first vaginal intercourse is about 17 years.¹⁵ Mean ages at initiation of oral-genital and anal intercourse have not been reported for current national data.

Documenting variation and typicality in the order and timing of life experiences—including sexual experience—across cohorts is important because they may differentially affect physical and emotional health within and across historical time.¹⁶ For example, initiating intimate behaviors (e.g., vaginal intercourse) before less intimate ones (e.g., kissing) has been linked to inconsistent use of contraception.¹⁷ Findings suggest differential psychosocial implications of oral-genital and vaginal intercourse,^18,19 which may make order of initiation important. Compared with adolescents with vaginal intercourse experience (with or without oral-genital sexual experience), adolescents who have had only oral-genital intercourse are less likely to feel guilty or used or to get into trouble with parents because of sexual activity. However, they are also less likely to experience sexual pleasure or to report feeling good about themselves.¹⁸ Early coitus is also linked to higher likelihood of sexual risk taking, including inconsistent condom use, more sexual partners, and, at least during adolescence, a higher likelihood of STDs.^20–23 Heterosexual anal intercourse is also a marker for sexual risk taking.²⁴

In summary, despite potential implications for sexual health and general well-being, few studies have documented the typicality of sexual timetables for multiple behaviors, and much of the available information is based on relatively small and geographically limited samples. To date, only NSFG data from 2002 forward allow estimates of adolescent oral-genital and anal intercourse for a nationally representative sample. Although a valuable resource, NSFG data do not include ages at initiation of noncoital behavior, limiting opportunities to evaluate implications of sexual timing.

The current study provided unique information about the timing (age at initiation) of oral-genital, vaginal, and anal intercourse and order of initiation for adolescents in grades 7 through 12 in the 1994 to 1995 school year. Documenting sexual timetables during adolescence provides a foundation for examining developmental implications of patterns and offers a point of reference to examine historical changes. We used data from the National Longitudinal Study of Adolescent Health (Add Health) to examine the

• prevalence of vaginal, oral-genital, and anal sexual experience during adolescence and whether prevalence varies by age cohort, biological sex, pubertal timing, race/ethnicity, family structure, and parent education;

• typicality of the earliest behavior (i.e., which is initiated first) across groups defined earlier;

• average timing (age) at initiation of oral-genital, vaginal, and anal intercourse and whether timing varies by groups defined earlier; and

• overlap in experience of oral-genital, vaginal, and anal intercourse during adolescence and whether overlap varies by biological sex.

METHODS

Add Health is a nationally representative, prospective cohort study of approximately 20 000 adolescents in grades 7 to 12 in the 1994 to 1995 school year. Four waves of in-home interviews followed up Add Health respondents from adolescence into adulthood. At Wave I (1994–1995), 20 745 respondents were selected from school rosters to complete an in-home interview. Wave IV interviews were conducted in 2008 with 15 701 original respondents, aged 24 to 32 years (80.3% of eligible respondents). More details are available elsewhere.²⁵ Add Health protocols were approved by the institutional review board at the University of North Carolina, Chapel Hill. Current analyses were deemed exempt.

We used data from Waves I and IV and excluded respondents missing valid Wave IV sample weights (n = 901); data on history of oral-genital, vaginal, or anal intercourse or the ages at which these behaviors first occurred (n = 575); or sociodemographic information (n = 424), yielding an analytic sample of 13 835.

Sexual Experience

At Wave IV, respondents used computer-assisted self-interviewing to report whether they had ever engaged in vaginal [“Have you ever had vaginal intercourse? (Vaginal intercourse is when a man inserts his penis into a woman’s vagina.)”], oral-genital [“Have you ever had oral sex? That is, has a partner ever put his or her mouth on your sexual organs, or have you put your mouth on his or her sexual organs?”], or anal sex [“Have you ever had anal intercourse? (By anal intercourse, we mean when a man inserts his penis into his partner’s anus or butt hole.)”]. For each endorsed behavior, respondents indicated their age (in years) at first experience. We created dichotomous variables indicating initiation of each behavior by age 18 years (1 = yes; 0 = no). For respondents reporting a year or more between initiation of first and second behaviors, we created dummy variables indicating the first behavior (e.g., vaginal intercourse first; 1 = yes; 0 = no). We also created variables indicating that none of the 3 behaviors was initiated by age 18 years (1 = yes; 0 = no) and whether the 2 (or 3) behaviors were initiated at the same age.

Sociodemographics

We selected 5 sociodemographic indicators associated with timing of initiation of vaginal intercourse. Biological sex and race/ethnicity were self-reported; categories for the latter were Hispanic, any single race; non-Hispanic Black; non-Hispanic White; non-Hispanic Asian; non-Hispanic American Indian; and other. Family structure was coded as 2 biological parents, other 2 parents (e.g., stepfamily), single mother, single father, or other. As a proxy for socioeconomic status, we used highest educational attainment of resident parent(s), categorized as less than high school, high school diploma or general equivalency diploma, some college or vocational training, or college graduate and higher. Chronological age was calculated at Wave IV and categorized as 24 to 29 years or 30 years and older. Self-perceived pubertal timing (“early,” “typical,” “late”), which is correlated with sex-specific indicators of pubertal status,²⁶ reflects adolescent reports of looking older, about average, or younger than same-age, same-sex peers. Sociodemographics, except chronological age, were measured at Wave I.

Analyses

We used weighted percentages and means to describe sociodemographic differences in the prevalence of each sexual behavior and which behavior was initiated first and biological sex differences in experiential overlap. We regressed each sexual experience by age 18 years on sociodemographics in 3 multivariate logistic models and regressed age at first experience of each behavior on sociodemographics in 3 ordinary least squares models. We used SAS Version 9.1.3 (SAS Institute Inc, Cary, NC) and Stata 10.0 (StataCorp, College Station, Tex) and applied survey commands to adjust for design and sampling weights to yield national estimates.

RESULTS

Table 1 shows sociodemographic characteristics of our analytic sample; the prevalence of engaging in oral-genital, vaginal, or anal intercourse during adolescence (i.e., by age 18 years) for the total sample and by sociodemographic groups; and adjusted odds ratios for associations between each sociodemographic characteristic and behavior. Overall, about two thirds of the adolescents had oral-genital intercourse, and three quarters had vaginal intercourse. Anal intercourse was the least common, at about 11%.

TABLE 1—

Prevalence of Oral-Genital, Vaginal, and Anal Intercourse by Age 18 Years, by Sociodemographic Characteristics: National Longitudinal Study of Adolescent Health, 2008

		Oral-Genital Intercourse		Vaginal Intercourse		Anal Intercourse
Sociodemographic  Characteristics	% (No.)	%	AOR (95% CI)	%	AOR (95% CI)	%	AOR (95% CI)
Total	100.0 (13 835)	67.4	—	75.2	—	10.7	—
Biological sex
Male	50.7 (6504)	72.3	1.68 (1.52, 1.87)***	73.5	0.85** (0.77, 0.94)	12.2	1.42*** (1.22, 1.66)
Female (Ref)	49.3 (7331)	62.3	1.00	77.0	1.00	9.1	1.00
Race/ethnicity
Non-Hispanic White (Ref)	66.6 (7494)	73.2	1.00	74.9	1.00	11.2	1.00
Non-Hispanic Black	15.4 (2919)	50.3	0.36*** (0.29, 0.43)	81.3	1.20 (0.97, 1.49)	6.4	0.51*** (0.41, 0.65)
Hispanic	11.7 (2181)	59.7	0.61*** (0.51, 0.73)	73.5	0.88 (0.73, 1.08)	13.6	1.23 (0.98, 1.54)
Non-Hispanic Asian	3.3 (872)	52.0	0.45*** (0.33, 0.61)	57.8	0.54** (0.38, 0.77)	8.7	0.83 (0.49, 1.42)
Non-Hispanic American Indian	2.0 (249)	75.4	1.02 (0.71, 1.48)	76.7	0.93 (0.58, 1.51)	14.2	1.20 (0.67, 2.14)
Non-Hispanic other race	1.0 (120)	67.5	0.73 (0.44, 1.19)	74.7	0.99 (0.59, 1.67)	8.6	0.71 (0.29, 1.76)
Family structure
2 biological parents (Ref)	55.7 (7415)	66.1	1.00	69.6	1.00	10.1	1.00
Other 2 parent	16.9 (2524)	74.6	1.53*** (1.30, 1.81)	83.1	2.01*** (1.64, 2.47)	11.7	1.16 (0.95, 1.43)
Single mom	20.1 (2899)	64.1	1.20* (1.04, 1.37)	80.7	1.56*** (1.34, 1.81)	10.1	1.11 (0.87, 1.41)
Single dad	2.9 (396)	72.8	1.44* (1.04, 1.98)	81.2	1.83** (1.27, 2.64)	18.1	1.90** (1.27, 2.83)
Other	4.4 (601)	66.9	1.55*** (1.23, 1.95)	86.0	2.36*** (1.66, 3.36)	12.0	1.44 (0.99, 2.08)
Parent education
< high school	12.0 (1722)	56.1	0.79* (0.65, 0.96)	75.6	1.40** (1.12, 1.77)	11.6	1.17 (0.85, 1.60)
High-school diploma or general   equivalency diploma	27.2 (3483)	70.1	1.26** (1.09, 1.47)	81.8	2.00*** (1.71, 2.33)	12.4	1.32* (1.04, 1.67)
Some college	29.9 (4049)	70.2	1.18* (1.03, 1.35)	77.3	1.53*** (1.32, 1.77)	9.8	0.99 (0.80, 1.23)
≥ College graduate (Ref)	30.8 (4581)	66.7	1.00	67.2	1.00	9.8	1.00
Pubertal timing
Early	41.1 (5517)	72.8	1.38*** (1.23, 1.55)	79.2	1.34*** (1.18, 1.51)	12.9	1.37** (1.13, 1.66)
Typical (Ref)	38.6 (5418)	66.3	1.00	73.1	1.00	9.8	1.00
Late	20.3 (2900)	58.6	0.78** (0.68, 0.90)	71.2	0.88 (0.77, 1.01)	8.1	0.81 (0.62, 1.06)
Age, y
24–29	70.3 (9399)	69.2	1.31*** (1.17, 1.46)	76.1	1.19* (1.04, 1.37)	11.1	1.21 (1.00, 1.46)
≥ 30 (Ref)	30.0 (4436)	63.2	1.00	73.1	1.00	9.7	1.00

Note. AOR = adjusted odds ratio; CI = confidence interval. Percentages were weighted to yield national probability estimates. On the basis of χ² tests, all characteristics were significantly associated with each type of sexual behavior at P ≤ .05 except for age group and anal intercourse. Odds ratios (ORs) for each sociodemographic characteristic were adjusted for all other sociodemographic characteristics (e.g., ORs for the effect of age on each type of sexual behavior were adjusted for biological sex, race/ethnicity, family structure, parent education, and pubertal timing). The sample size was n = 13 835.

*P < .05; **P < .01; ***P < .001.

Higher percentages of females than males had vaginal intercourse during adolescence, but males were more likely to have had oral-genital and anal intercourse (Table 1). About three quarters of the non-Hispanic White and non-Hispanic American Indian adolescents had oral-genital intercourse by age 18 years; among other racial/ethnic groups, percentages ranged from 50% to 68%. Prevalence of vaginal intercourse also varied by race/ethnicity, although non-Hispanic Asian respondents were the only group with significantly lower odds of having vaginal intercourse compared with non-Hispanic White respondents. With the exception of non-Hispanic White and American Indian individuals, vaginal intercourse was more prevalent than oral-genital intercourse during adolescence. This difference was especially striking for non-Hispanic Black adolescents, with 81% reporting vaginal intercourse but only 50% reporting oral-genital intercourse. Differences between non-Hispanic Black and non-Hispanic White male and female respondents were similar in magnitude and direction for vaginal and anal intercourse but strikingly different for oral-genital intercourse. Three quarters of non-Hispanic White and 79% of non-Hispanic Black male respondents reported adolescent oral-genital sexual activity. However, 70% of White female respondents but only 38% of Black female respondents reported oral-genital intercourse (results not shown). Overall, non-Hispanic Black respondents were also the least likely to report adolescent anal intercourse (6%) and were the only group whose odds of having anal intercourse were significantly lower than for the non-Hispanic White group.

Respondents from family structures other than 2 biological parents were more likely to report oral-genital and vaginal intercourse, with higher percentages reporting vaginal than oral-genital intercourse. In contrast, similar percentages of respondents from households with 2 biological parents reported oral-genital and vaginal intercourse during adolescence. Percentages reporting anal intercourse were similar across family structure groups (10%–12%), with the exception of the single father family structure (18%).

Respondents with college-graduate parents were least likely to report vaginal sexual activity, but unlike in other groups, similar percentages reported oral-genital and vaginal intercourse (about 67% for each behavior). Higher percentages of respondents with less educated parents reported anal intercourse. Compared with respondents with typical pubertal timing, earlier-maturing adolescents had greater odds of reporting each type of experience. Later-maturing respondents had lower odds of oral-genital sexual activity. Younger respondents were more likely to report adolescent oral-genital and vaginal intercourse before age 18 years.

Typicality of Earliest Behavior

Table 2 shows the percentages of respondents who initiated each of the 3 sexual behaviors first or who reported no oral-genital, vaginal, or anal intercourse by age 18 years. The last column includes percentages who reported initiation of 2 or 3 behaviors at the same age. Overall, similar percentages (33%) either had vaginal intercourse first or initiated 2 (typically oral-genital and vaginal) or 3 behaviors at the same age (i.e., within a 12-month period), whereas 15% reported initiating oral-genital intercourse first. Fewer than 1% reported anal intercourse as their first behavior. About 1 in 5 respondents reported no sexual experience as of age 18 years.

TABLE 2—

Weighted Percentages of Respondents Who Reported by Age 18 Years No Sexual Activity, 1 of the 3 Types of Sexual Intercourse First, or 2 or 3 Sexual Behaviors Initiated at the Same Age, by Sociodemographic Characteristics: National Longitudinal Study of Adolescent Health, 2008

Sociodemographic Characteristics	No Sexual Activity, % (No.)	Oral-Genital Intercourse First, % (No.)	Vaginal Intercourse First, % (No.)	Anal Intercourse First, % (No.)	First 2 or 3 Behaviors Reported at Same Age, % (No.)
Total	19.2 (2766)	14.7 (1829)	33.3 (4901)	0.3 (41)	32.6 (4298)
Biological sex
Male	19.3 (1300)	18.3 (1104)	23.6 (1643)	0.4 (23)	38.4 (2434)
Female	19.0 (1466)	11.0 (725)	43.3 (3258)	0.2 (18)	26.6 (1864)
Race/ethnicity
Non-Hispanic White	18.9 (1464)	17.7 (1279)	26.5 (2018)	0.2 (16)	36.7 (2717)
Non-Hispanic Black	14.5 (422)	6.8 (206)	61.7 (1780)	0.4 (13)	16.6 (498)
Hispanic	21.9 (483)	10.3 (217)	37.9 (805)	0.3 (—)	29.7 (667)
Non-Hispanic Asian	38.0 (335)	6.7 (74)	22.5 (166)	0.2 (—)	32.6 (294)
Non-Hispanic American Indian	17.9 (37)	16.5 (37)	33.1 (91)	0.0 (0)	32.6 (84)
Non-Hispanic other race	18.6 (25)	13.3 (16)	26.4 (41)	0.0 (0)	41.7 (38)
Family structure
2 biological parents	23.6 (1866)	16.7 (1073)	26.1 (2105)	0.1 (10)	33.5 (2361)
Other 2 parent	12.4 (323)	13.0 (332)	39.0 (993)	0.3 (10)	35.3 (866)
Single mom	15.1 (461)	12.6 (313)	43.5 (1326)	0.6 (18)	28.3 (781)
Single dad	15.5 (59)	11.9 (59)	36.6 (142)	0.0 (0)	36.0 (136)
Other	10.9 (57)	8.2 (52)	52.7 (335)	0.5 (—)	27.7 (154)
Parent education
< high school	20.4 (362)	8.8 (136)	43.8 (770)	0.3 (—)	26.7 (447)
High-school diploma or general equivalency diploma	13.9 (529)	11.8 (388)	40.1 (1441)	0.3 (13)	33.9 (1112)
Some college	18.1 (721)	13.9 (500)	33.5 (1472)	0.2 (—)	34.4 (1347)
≥ College graduate	24.5 (1154)	20.3 (805)	22.9 (1218)	0.3 (12)	32.0 (1392)
Pubertal timing
Early	15.1 (880)	14.6 (743)	35.0 (2028)	0.3 (13)	35.0 (1853)
Typical	20.9 (1195)	16.0 (760)	30.6 (1800)	0.3 (19)	32.2 (1644)
Late	24.1 (691)	12.3 (326)	34.9 (1073)	0.2 (—)	28.5 (801)
Age, y
24–29	18.0 (1785)	15.8 (1333)	33.4 (3315)	0.2 (26)	32.6 (2940)
≥ 30	22.0 (981)	12.1 (496)	33.1 (1586)	0.4 (15)	32.5 (1358)

Note. Dash indicates that cell size is too small to be displayed. Percentages reflect row percents. Bivariate tests and multivariate modeling were not conducted because of the small cell sizes for some combinations. The sample size was n = 13 835.

Striking differences were seen across sociodemographic groups. Almost 40% of the males reported initiating 2 or more behaviors within the same year, compared with only a quarter of the females. Among those who staggered initiation, female respondents were much more likely to have vaginal intercourse first, whereas similar percentages of male respondents initiated oral-genital and vaginal intercourse first. Across race/ethnicity, non-Hispanic Asian respondents had the largest (38%) representation in the no experience category. Non-Hispanic Black individuals were the least likely to have initiated more than 1 type of sexual behavior within the same year (17% vs 30%–42% in the other groups). Although a greater percentage of non-Hispanic White adolescents reported initiating vaginal intercourse first (26%) than initiating oral-genital intercourse first (18%), the difference was smaller than that for other racial/ethnic groups. The difference was especially striking among non-Hispanic Black respondents; only 7% had oral-genital intercourse first, and 62% had vaginal intercourse first.

Higher percentages of respondents from all family structures reported having vaginal before oral-genital intercourse, although differences were smaller for respondents from the households with 2 biological parents. The latter were the least likely to initiate adolescent vaginal intercourse and the most likely to report no sexual experience. Higher percentages of respondents with less educated parents had vaginal before oral-genital intercourse. Similar percentages of respondents with a college graduate parent reported initiating oral-genital and vaginal intercourse first. Initiating 2 or more behaviors within a year was relatively more common among those who matured earlier, whereas adolescents who matured later were more likely to report no experience.

Timing of Initiation

Overall, average age at first vaginal intercourse was slightly younger (weighted mean = 15.5 years; SE = 0.02) than age at first oral-genital intercourse (weighted mean = 15.8 years; SE = 0.02). The average age at first anal intercourse, among those who had had anal intercourse by age 18 years, was almost a year older (weighted mean = 16.4 years; SE = 0.06) and more variable (results not shown). Mean ages at initiation are listed by sociodemographic characteristics in Table 3; with few exceptions, sociodemographics were associated with ages at initiating oral-genital and vaginal intercourse in multivariate ordinary least squares regression models. Respondents who were male, were from a household structure other than 2 biological parents, or matured earlier were younger at first oral-genital sexual experience. Non-Hispanic Asian respondents were significantly older. For age at first vaginal intercourse, associations with family structure and pubertal timing were similar to those seen for oral-genital intercourse. However, non-Hispanic Black adolescents were younger than non-Hispanic White adolescents at first vaginal intercourse (vs a similar age at first oral-genital sexual experience), and any parent education less than a college degree was associated with a younger age at first vaginal intercourse. Being male was the only characteristic associated with age at first anal intercourse.

TABLE 3—

Mean Ages at Initiation, Regression Coefficients, and SE of First Oral-Genital, Vaginal, and Anal Intercourse Among Respondents Who Reported Initiation by Age 18, by Sociodemographic Characteristics: National Longitudinal Study of Adolescent Health, 2008

	Oral-Genital Intercourse Before Age 18 (n = 8912)		Vaginal Intercourse Before Age 18 (n = 10 343)		Anal Intercourse Before Age 18 (n = 1368)
Sociodemographic  Characteristics	Mean Age at Initiation (SE)	b (SE)	Mean Age at Initiation (SE)	b (SE)	Mean Age at Initiation (SE)	b (SE)
Biological sex
Male	15.6 (0.03)	−0.43*** (0.06)	15.5 (0.03)	−0.06 (0.05)	16.3 (0.09)	−0.42* (0.17)
Female	16.0 (0.03)	1.00	15.5 (0.02)	1.00	16.7 (0.08)	1.00
Race/ethnicity
Non-Hispanic White	15.8 (0.03)	1.00	15.6 (0.02)	1.00	16.4 (0.08)	1.00
Non-Hispanic Black	15.8 (0.06)	0.16 (0.09)	15.1 (0.04)	−0.41*** (0.09)	16.4 (0.20)	0.25 (0.37)
Hispanic	15.7 (0.06)	−0.02 (0.13)	15.4 (0.06)	−0.14 (0.13)	16.4 (0.13)	0.20 (0.27)
Non-Hispanic Asian	16.3 (0.08)	0.37** (0.12)	16.0 (0.08)	0.24 (0.13)	16.8 (0.28)	0.50 (0.49)
Non-Hispanic American Indian	15.9 (0.13)	0.19 (0.18)	15.4 (0.15)	−0.12 (0.18)	16.8 (0.26)	0.49 (0.29)
Non-Hispanic other race	15.3 (0.33)	−0.44 (0.45)	15.4 (0.17)	−0.16 (0.24)	15.6 (0.59)	−0.67 (0.62)
Family structure
2 biological parents	16.0 (0.03)	1.00	15.8 (0.02)	1.00	16.7 (0.08)	1.00
Other 2 parent	15.7 (0.05)	−0.30*** (0.07)	15.3 (0.04)	−0.45*** (0.06)	16.4 (0.13)	−0.29 (0.18)
Single mom	15.5 (0.06)	−0.52*** (0.09)	15.2 (0.04)	−0.42*** (0.08)	16.1 (0.18)	−0.68 (0.35)
Single dad	15.4 (0.12)	−0.59** (0.19)	14.9 (0.12)	−0.79*** (0.18)	16.4 (0.21)	−0.21 (0.24)
Other	15.5 (0.12)	−0.55** (0.15)	14.9 (0.08)	−0.71*** (0.13)	15.5 (0.42)	−1.13 (0.59)
Parent education
< high school	15.6 (0.06)	−0.24 (0.13)	15.3 (0.06)	−0.42*** (0.11)	16.0 (0.20)	−0.44 (0.41)
High-school diploma or general   equivalency diploma	15.7 (0.04)	−0.19* (0.08)	15.3 (0.04)	−0.43*** (0.07)	16.5 (0.10)	0.03 (0.28)
Some college	15.9 (0.04)	0.03 (0.07)	15.5 (0.03)	−0.23** (0.06)	16.6 (0.11)	0.10 (0.32)
≥ College graduate	15.9 (0.03)	1.00	15.9 (0.03)	1.00	16.5 (0.13)	1.00
Pubertal timing
Early	15.6 (0.03)	−0.34*** (0.05)	15.2 (0.03)	−0.45*** (0.06)	16.4 (0.09)	0.07 (0.20)
Typical	16.0 (0.03)	1.00	15.7 (0.03)	—	16.4 (0.12)	—
Late	16.0 (0.05)	0.08 (0.09)	15.7 (0.05)	0.09 (0.08)	16.6 (0.14)	0.26 (0.23)
Age, y
24–29	15.8 (0.02)	−0.08 (0.08)	15.5 (0.02)	−0.04 (0.08)	16.5 (0.07)	0.22 (0.23)
≥ 30	15.8 (0.04)	1.00	15.5 (0.04)	1.00	16.2 (0.15)	1.00

Note. Means are weighted to reflect national population estimates.

*P < .05; **P < .01; ***P < .001.

Comparisons between patterns in Tables 1 and 3 indicate that behavior prevalence and timing of onset are not necessarily in tight synchrony. For example, non-Hispanic Black adolescents were one third as likely as non-Hispanic White adolescents to have had oral-genital sexual activity by age 18 (Table 1), but mean age was the same among those who did initiate oral-genital intercourse (Table 3). Similarly, adolescents whose parents had less than a high-school diploma had the lowest prevalence (within this characteristic) of engaging in oral-genital intercourse (Table 1), but their average age at initiation did not differ from that of teenagers with college educated parents (Table 3).

Overlap in Sexual Experiences During Adolescence

Figure 1 shows percentages of male and female respondents who initiated different combinations of oral-genital, vaginal, and anal intercourse by age 18 years. The most common combination was to have both vaginal and oral-genital sexual experience during adolescence (56% of males and 51% of females). However, for male respondents, the next most common pattern was experience with all 3 types (11%), followed by vaginal intercourse only (8%) and oral-genital experience only (6%). For female respondents, the most common pattern after the combination of oral-genital and vaginal intercourse was vaginal intercourse only (19%), followed by all 3 types (9%) and oral-genital experience only (4%). The remaining patterns were uncommon for male and female respondents.

FIGURE 1—

Venn diagram illustrating the overlap among initiation of vaginal, oral-genital, and anal intercourse, by biological sex, by age 18 years among male and female adolescents: National Longitudinal Study of Adolescent Health, 2008.

Denominator is all male and all female adolescents. Percentages do not sum to 100 because respondents with no sexual experience by age 18 years are not shown. Dash indicates that cell size is too small to be displayed.

^a1300 male adolescents reported no sexual experiences by age 18.

^b1466 female adolescents reported no sexual experiences by age 18.

DISCUSSION

We used nationally representative data for individuals who were adolescents between 1994 and 2001 (including understudied groups such as American Indians) to document the prevalence of oral-genital, vaginal, and anal intercourse during adolescence; the typicality of earliest sexual behaviors; and mean ages at initiation. One in 5 adolescents from these cohorts had engaged in none of these sexual behaviors by age 18 years. More than two thirds reported vaginal or oral-genital sexual activity, but only about half reported both. About 1 in 10 adolescents from these cohorts reported anal intercourse experience. About a third of the adolescents initiated oral-genital and vaginal intercourse within a 1-year period, and another third initiated vaginal intercourse first, suggesting that oral-genital intercourse did not postpone vaginal intercourse for most adolescents. This pattern is consistent with findings for more recent cohorts of community-based samples of high-school students.²⁷

Although we did not test for statistical significance, differences in the typicality of the earliest sexual behavior were evident for most sociodemographic characteristics. The similar prevalence of oral-genital and vaginal intercourse in adolescence for some groups but not others indicate complex patterns of differential acceptance of oral-genital intercourse during adolescence across multiple sociodemographic indicators. In multivariate models, we found that these characteristics were significantly and uniquely associated with timing of sexual initiation. Some patterns (e.g., earlier mean age at first vaginal intercourse among non-Hispanic Black adolescents; associations between early pubertal timing and early coital transition) have been previously reported,^28,29 but others are unique. For example, to our knowledge this is the first report of linkages between early pubertal timing and greater likelihood of oral-genital and anal intercourse experience during adolescence. Finally, our analyses indicate independence of demographic typicality of a sexual behavior and individual timing of initiation. Future research should examine whether different patterns (e.g., non-Hispanic Black adolescents who initiate oral-genital intercourse early in adolescence) have differential implications for individual sexual development and for population health.

Our overall estimates of vaginal intercourse experience during adolescence were higher than those from the most recent Youth Risk Behavior Survey and NSFG.^5,6 (Youth Risk Behavior Survey estimates for high-school seniors varied between 60.9% and 68.3% between 1993 and 2001.³⁰ NSFG estimates for 18- and 19-year-old men varied between 75% [1995] and 64% [2002]; for women, estimates varied between 68% [1995] and 69% [2002].³¹) However, our estimates of oral-genital intercourse were similar to the estimates in the 2006 to 2008 NSFG for both male and female repondents, and our estimates for anal intercourse were lower. We cannot isolate the sources of these differences (e.g., sampling, question wording, period of retrospection, cohorts), but they may partly represent differential changes over historical time in adolescent initiation of these behaviors. For vaginal intercourse, these differences are consistent with documented declines in adolescent initiation during the 1990s.⁵ Historical comparisons are more difficult for oral-genital and anal intercourse, but—to the extent that they represent historical variation rather than methodological differences—comparisons of Add Health patterns to those of the more recent NSFG indicate relatively little change in adolescent oral-genital sexual activity since the 1990s but perhaps increases in anal intercourse.

Limitations

Because respondents were 24 to 32 years old when they reported ages at first sexual experiences, the period of retrospection may be lengthy for some individuals and behaviors. Respondents reported ages at first experiences in whole years; therefore, we were unable to order behaviors initiated at the same age. Data limitations also prevented us from distinguishing whether first experiences of oral-genital and anal intercourse were in the context of same- or opposite-sex relationships. This limitation may contribute to differences in prevalence estimates and sociodemographic correlates between our findings and NSFG data reported here, which were limited to opposite-sex experiences. Our analyses of partnered sexual experiences did not distinguish between giving and receiving oral-genital or anal intercourse—experiences that have different implications for STD risk. Finally, our analyses did not identify the interpersonal contexts and psychosocial experiences associated with differential timing of sexual initiation. Understanding the developmental implications of differences in sexual timetables ultimately must be informed by the meaning of the sexual act at that time point for the adolescent.

Conclusions

This work is one of several ongoing efforts to develop a more comprehensive description of adolescent sexual experience and development in the United States. Current analyses represent a useful point of comparison, especially for noncoital activity, between adolescent experiences toward the end of the 20th century (i.e., during the 1990s) and experiences in the 21st century that are being documented in more recent cross-sectional samples such as the NSFG.

Few studies have examined the developmental implications of sexual timetables based on multiple behaviors. More longitudinal work is needed to understand the sources and meaning of sociodemographic differences documented here and their potential implications. For example, it is unclear whether departures from typicality of behavior and timing of behavior have different consequences for health and well-being or how sexual timetables relate to patterns of contraceptive use, partner accumulation, and sexual risk behaviors into adulthood. Better understanding of these patterns could inform future policy, education, and prevention efforts.