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. Author manuscript; available in PMC: 2021 Jun 8.
Published in final edited form as: Afr J Reprod Health. 2021 Feb;25(1):101–113. doi: 10.29063/ajrh2021/v25i1.12

Factors associated with age of first sex among women screened for an observational contraceptive vaginal ring study in Kisumu, Kenya, 2014

Ken Ondenge 1,*, Roman Gvetadze 2, George Otieno 1, Deborah A Gust 2, Eleanor McLellan-Lemal 2
PMCID: PMC8186808  NIHMSID: NIHMS1683717  PMID: 34077116

Abstract

Sex at an early age can have later life negative health outcomes. Insights on early sexual activity may help in the development of future health-promotion products and interventions related to pregnancy and sexually transmitted infections (STIs) prevention. Among Kenyan women participating in a contraceptive vaginal ring study, we determined: (1) the proportion with first sex at ≤15 years (early sex) and (2) factors associated with early sex. Baseline data collection and testing for pregnancy, STIs, and HIV were undertaken. A log-binomial or a modified Poisson regression was used to estimate univariable prevalence ratios and multivariable adjusted prevalence ratios (aPRs). Among 332 women aged 18–34 years, the median age of first sex was 16 years, with 40.1% experiencing early sex. Overall, 29.8% reported an older first sex partner (≥5 years); 83.9% indicated lack of readiness or intentions at first sex; and 56.2% received money, gifts, or favors as part of first sex. Early sex was more prevalent among inherited widows (a Luo cultural practice, aPR 1.49), gift recipients (aPR 1.38), women with a forced/unwanted sex history (aPR 1.42), or those with a partner of unknown or positive HIV status in the past 3 months (aPR 1.45). Sex before or at the age 15 may be associated with higher sexual risk behaviors. Complex power and gender relations may additionally influence exposure to sexual risk in our research setting.

Keywords: Kenya, women, age of first sex, risk factors

Introduction

In sub-Saharan Africa (SSA), females tend to experience first sex at earlier ages than males1. Studies conducted in SSA define early sex at age 15 or younger1. Early age of first sex among adolescent girls and young women in SSA has been associated with a lack of or inconsistent contraception, including condom use2, having risky sexual partners, age-disparate sex, multiple partners, unintended pregnancy, unsafe abortions, and increased risk of HIV and other sexually transmitted infections (STIs)3. Early sex is also more likely to be non-consensual, even when reported as consensual, given that the decision to engage in intercourse is not made autonomously4. In situations where early sex is coerced or forced, psychological as well as physiological trauma can affect subsequent sexual risk behavior5. Structural factors linked to early age of first sex include economic and gender inequality, lack of education6, as well as cultural and social factors, including family instability7 and early marriage expectations8.

In Kenya, the median age of first sex among women aged 20–49 years is reported as 18 years, with women in rural areas experiencing it at an earlier age compared to those in urban areas9. In the Nyanza region of Kenya (the location of our study), the median age of first sex (16.4 years) is younger compared to the overall country9. The HIV rates in this geographical region are also among the highest in the country10. Nationally, an estimated 5% of adolescent girls (15–19 years of age) and 14% of young women (20–24 years of age) are living with HIV10. While there is a large amount of literature regarding adolescent sexual and reproductive health in developing countries5, it is important to continue to evaluate early sex among women given the potential relationship between early sex and future HIV risk behaviors and poorer health outcomes3. Insights on early sexual activity may also help in the development of health-promotion products and activities, such as those related to contraception and STI prevention.

As mentioned previously, absent or inconsistent contraceptive use among women is associated with early sex2. Additional insights on factors associated with early sex may be gleaned by focusing on young adult women who are contraceptive users (i.e., already on their own accord taking part in a health promoting behavior). We conducted an observational study in Kisumu, Kenya, among current hormonal contraceptive users to assess acceptability and adherence to a contraceptive cervical vaginal ring (CVR). From baseline data collected we 1) determined the proportion of women who experienced early sex (at ≤15 years) and 2) identified factors associated with experiencing early sex.

Methods

Study design

We conducted a single-arm observational study, from which baseline data are reported here. Details regarding the study design and methods have been published elsewhere11. In brief, the study involved a pre-CVR-use phase whereby women terminated existing oral or injectable contraceptive use before switching over to CVR use. CVR use occurred for six months before ending with an up to 3-month post-product phase during which women returned to oral or injectable contraceptives before exiting the study. Given that the CVR does not protect against HIV and other STIs, women were provided condoms and received risk reduction counseling at all study visits.

Participant selection

We undertook study screening from April 2014 to November 2014. We targeted women who were 18–34 years of age and had engaged in more than one episode of vaginal intercourse on different days within the past 30 days, were not currently pregnant and not intending to get pregnant for the next 12 months, lived in the Kisumu catchment area (≈150 kilometers from Kisumu), were within 30 days of their last oral contraceptive cycle or within 3 months of receipt of their last depot medroxy-progesterone acetate (DMPA) injection, had never been diagnosed with HIV, and were willing to undergo monthly pregnancy testing, periodic pelvic examination, and HIV testing at screening, 3 months and 6 months11. In addition, women had to be able to: i) understand and read English, Dholuo, or Swahili, ii) comprehend study procedures, and iii) provide written informed consent.

Data collection

After completing a brief pre-screening medical history by staff-administered computer-assisted personal interview (CAPI), all women who met eligibility criteria consented to complete additional behavioral and medical screening procedures. Specifically, women screened completed a self-administered audio computer-assisted interview (ACASI), provided a medical history via CAPI, and underwent laboratory testing as well as physical examination that included a pelvic exam. Pregnancy, STI, and HIV testing procedures were conducted according to the Kenya National Guidelines.

Measures and statistical analysis

Women screened must have reported that they had sex within the past 3 months and provided age of first sex to be included in our analysis sample. We collected demographics (age, marital status, education, employment status, etc.), psychosocial information (psychological distress in the past 30 days and history of depression), self-reported CAPI medical history and laboratory results for pregnancy, STI, and HIV. We also inquired about the contextual information related to first sex (age of partner, sexual readiness, gifts or material goods received, etc.) and behaviors occurred over a woman’s lifetime and in the past 12 months (collectively denoted as historical behaviors) as well as recent behaviors occurred 3–6 months before the screening interview.

Women with a history of marriage were asked whether they had ever been inherited. Among the Luo of western Kenya, widowed women may engage in a cultural inheritance practice, which is intended to ensure that a widow and her children have needed social and economic support12. A widow is considered a “wife of the grave” in that she remains married to her deceased spouse12. Even if a widow remarries or cohabits with her inheritor or another partner, her marriage to her deceased spouse is not dissolved13. Traditionally, a widow was inherited by, and became a wife to, a male relative of her deceased husband (levirate union); however, in more modern times, a non-in-law or professional inheritor enables a widow to comply with this cultural practice14. Inheritance compliance is exempt for women who are unable to bear children due to infertility or who have reached menopause. Of note, our question on inheritance did not ask women to specify whether it was based on a traditional levirate union or a modern variant. To establish consistency with other SSA studies, we define early sex as self-report of first sex at 15 years of age or younger. All the potential demographic, behavioral, psychosocial, and contextual factors, medical history, and laboratory results were coded as categorical variables with 2–4 categories and are listed in Tables 1–3. The goal of this analysis was to estimate the prevalence of women who had experienced early sex and compare it across the independent variable categories using prevalence ratios. We summarized the categorical variables using frequency counts and percentages, and characterized continuous variables using median and interquartile range (IQR). Within the generalized linear regression framework, we used a binomial regression with a log link15 or a modified Poisson approach16 to estimate univariable prevalence ratios (PRs) and multivariable adjusted prevalence ratios (aPRs).

Table 1:

Age of first sex, by demographic and health characteristics (N=332)a, Kisumu contraceptive vaginal ring study, Kisumu, Kenya, 2014

Variable Total
(N=332)
n (col %)		 First sex at ≤15 yrs. (N=133)
n (col %)		 First sex at >15 yrs.
(N=199)
n (col %)		 Prevalence of first sex at ≤15 yrs.
(row %)		 PR ≤15 vs. >15 yrs. (CI) p-value
Age at screening 0.678
18–24 163 (49.1) 69 (51.9) 94 (47.2) 42.3 1.07 (0.73, 1.56) 0.731
25–29 116 (34.9) 43 (32.3) 73 (36.7) 37.1 0.94 (0.62, 1.41) 0.749
30–34 53 (16.0) 21 (15.8) 32 (16.1) 39.6 Ref.
Ethnic group
Luo 295 (89.1) 120 (90.2) 175 (88.4) 40.7 1.13 (0.71, 1.78) 0.609
Non-Luo 36 (10.9) 13 (9.8) 23 (11.6) 36.1 Ref.
Marital status 0.414
Single 58 (17.8) 19 (14.5) 39 (20.1) 32.8 0.84 (0.51, 1.41) 0.517
Married 218 (67.1) 93 (71.0) 125 (64.4) 42.7 1.10 (0.75, 1.62) 0.626
Widowed/Divorced/Separated/Other 49 (15.1) 19 (14.5) 30 (15.5) 38.8 Ref.
Ever been inheritedb,c
Yes 82 (25.1) 45 (33.8) 37 (19.1) 54.9 1.53 (1.18, 1.98) 0.001
No 245 (74.9) 88 (66.2) 157 (80.9) 35.9 Ref.
Religion 0.216
Roman Catholic 149 (45.0) 57 (42.9) 92 (46.5) 38.3 0.77 (0.55, 1.07) 0.114
Other Christian 126 (38.1) 48 (36.1) 78 (39.4) 38.1 0.76 (0.54, 1.07) 0.121
Non-Christian 56 (16.9) 28 (21.1) 28 (14.1) 50.0 Ref.
Highest level of educationc
Primary or less 211 (63.9) 99 (74.4) 112 (56.9) 46.9 1.64 (1.19, 2.26) 0.002
Secondary or more 119 (36.1) 34 (25.6) 85 (43.1) 28.6 Ref.
Employment status
Employed 203 (61.5) 81 (60.9) 122 (61.9) 39.9 0.97 (0.74, 1.27) 0.851
Unemployed 127 (38.5) 52 (39.1) 75 (38.1) 40.9 Ref.
Main source of income 0.329
None 12 (3.6) 4 (3.0) 8 (4.0) 33.3 0.74 (0.33, 1.68) 0.473
Salary-based 188 (56.8) 70 (52.6) 118 (59.6) 37.2 0.83 (0.63, 1.08) 0.159
Not salary-based 131 (39.6) 59 (44.4) 72 (36.4) 45.0 Ref.
Psychological distress in past 30 days 0.134
Low (score 0–4) 71 (21.4) 23 (17.3) 48 (24.1) 32.4 Ref.
Medium (score 5–12) 198 (59.6) 79 (59.4) 119 (59.8) 39.9 1.23 (0.84, 1.80) 0.279
High (score 13–24) 63 (19.0) 31 (23.3) 32 (16.1) 49.2 1.52 (1.00, 2.31) 0.051
Self-reported history of depression
Yes 62 (18.8) 26 (19.5) 36 (18.3) 41.9 1.05 (0.76, 1.46) 0.769
No 268 (81.2) 107 (80.5) 161 (81.7) 39.9 Ref.
Perceived overall health statusc
Poor 42 (12.8) 22 (16.5) 20 (10.2) 52.4 1.35 (0.98, 1.87) 0.066
Good/Excellent 287 (87.2) 111 (83.5) 176 (89.8) 38.7 Ref.
Abnormal vaginal bleeding in past 12 monthsc
Yes 71 (21.4) 40 (30.1) 31 (15.6) 56.3 1.58 (1.22, 2.05) 0.001
No 261 (78.6) 93 (69.9) 168 (84.4) 35.6 Ref.
Self-reported history of sexually transmitted infection (STI)
Yes 75 (22.6) 35 (26.3) 40 (20.1) 46.7 1.22 (0.92, 1.63) 0.169
No 257 (77.4) 98 (73.7) 159 (79.9) 38.1 Ref.
STI/BVd test result (any)
Positive 228 (69.1) 93 (69.9) 135 (68.5) 40.8 1.04 (0.78, 1.39) 0.789
Negative 102 (30.9) 40 (30.1) 62 (31.5) 39.2 Ref.
History of HIV
Yes 9 (2.7) 4 (3.0) 5 (2.5) 44.4 1.11 (0.53, 2.34) 0.778
No 323 (97.3) 129 (97.0) 194 (97.5) 39.9 Ref.
HIV test result
Positive 47 (14.2) 18 (13.5) 29 (14.6) 38.3 0.95 (0.64, 1.40) 0.779
Negative 284 (85.8) 115 (86.5) 169 (85.4) 40.5 Ref.
Pregnancy test result
Positive 2 (0.6) 1 (0.8) 1 (0.5) 50.0 1.25 (0.31, 5.01) 0.757
Negative 329 (99.4) 132 (99.2) 197 (99.5) 40.1 Ref.
Open in a new tab

yrs. = years; CI = 95% confidence interval (CI); PR = prevalence ratio

a

Analysis sample was restricted to women screened who reported that they had sex within the past 3 months and provided age of first sex. Sample sizes fluctuate slightly for some variables due to missing data.

b

A traditional Luo cultural practice whereby a widow is required to marry a male relative of her late husband (often his brother). In modern times, a non-in-law or professional inheritor enables a widow to comply with this cultural practice14.

c

Variables significant at 0.1 level were considered for multivariable analysis.

d

Sexually transmitted infection = STI/BV = bacterial vaginosis. Assessment of STIs included testing for herpes simplex virus type 2, gonorrhea, syphilis, and chlamydia. While BV is not classified as a sexually transmitted infection, it increases a woman’s risk for acquiring HIV and other sexually transmitted infections.

Table 3:

Age of first sex, by historical behaviors (N=332)a, Kisumu contraceptive vaginal ring study, Kisumu, Kenya, 2014

Variable Total (N=332)
n (col %)		 First sex at ≤15 yrs.
(N=133)
n (col %)		 First sex at >15 yrs.
(N=199)
n (col %)		 Prevalence of first sex at ≤15 yrs.
(row %)		 PR ≤15 vs. >15 yrs.
(CI)		 p-value
Ever ended up in trouble due to alcohol use
Yes 29 (8.8) 11 (8.3) 18 (9.1) 37.9 0.94 (0.58, 1.53) 0.804
No 300 (91.2) 121 (91.7) 179 (90.9) 40.3 Ref.
Ever engaged in illicit/recreational drug use
Yes 19 (5.7) 10 (7.5) 9 (4.5) 52.6 1.34 (0.86, 2.10) 0.201
No 313 (94.3) 123 (92.5) 190 (95.5) 39.3 Ref.
Number of lifetime sexual partners 0.331
One 52 (15.9) 17 (12.9) 35 (17.9) 32.7 Ref.
Two-three 171 (52.3) 68 (51.5) 103 (52.8) 39.8 1.22 (0.79, 1.87) 0.374
Four or more 104 (31.8) 47 (35.6) 57 (29.2) 45.2 1.38 (0.89, 2.15) 0.153
Ever experienced physically forced/unwanted sexb
Yes 109 (33.0) 58 (43.6) 51 (25.9) 53.2 1.57 (1.22, 2.02) 0.001
No 221 (67.0) 75 (56.4) 146 (74.1) 33.9 Ref.
Ever experienced non-sexual physical violence by sexual partnerb
Yes 78 (23.5) 39 (29.3) 39 (19.6) 50.0 1.35 (1.03, 1.78) 0.031
No 254 (76.5) 94 (70.7) 160 (80.4) 37.0 Ref.
Ever had sexual intercourse during mensesb
Yes 70 (21.6) 36 (27.7) 34 (17.5) 51.4 1.39 (1.05, 1.84) 0.021
No 254 (78.4) 94 (72.3) 160 (82.5) 37.0 Ref.
Ever received money from a sexual partner to take care of her menstrual period needsb
Yes 108 (32.6) 52 (39.1) 56 (28.3) 48.1 1.33 (1.02, 1.72) 0.035
No 223 (67.4) 81 (60.9) 142 (71.7) 36.3 Ref.
A sexual partner ever bought her sanitary pads to look after her menstrual period
Yes 265 (80.1) 102 (76.7) 163 (82.3) 38.5 0.82 (0.61, 1.10) 0.191
No 66 (19.9) 31 (23.3) 35 (17.7) 47.0 Ref.
Excluding first sex, ever used sex to get things she wanted/needed
Yes 116 (35.0) 52 (39.1) 64 (32.3) 44.8 1.19 (0.91, 1.55) 0.199
No 215 (65.0) 81 (60.9) 134 (67.7) 37.7 Ref.
Excluding first sex, ever used sex to get money for herself
Yes 59 (17.9) 25 (19.1) 34 (17.2) 42.4 1.08 (0.77, 1.51) 0.653
No 270 (82.1) 106 (80.9) 164 (82.8) 39.3 Ref.
Excluding first sex, ever used sex to get a place to stayb
Yes 30 (9.1) 16 (12.2) 14 (7.1) 53.3 1.39 (0.96, 2.00) 0.078
No 299 (90.9) 115 (87.8) 184 (92.9) 38.5 Ref.
Excluding first sex, ever used sex to get food
Yes 20 (6.1) 8 (6.1) 12 (6.1) 40.0 1.00 (0.58, 1.75) 0.986
No 309 (93.9) 123 (93.9) 186 (93.9) 39.8 Ref.
Excluding first sex, ever used sex to get gifts
Yes 14 (4.3) 6 (4.6) 8 (4.0) 42.9 1.08 (0.58, 2.01) 0.808
No 315 (95.7) 125 (95.4) 190 (96.0) 39.7 Ref.
Excluding first sex, ever used sex to get money for someone else
Yes 6 (1.8) 3 (2.3) 3 (1.5) 50.0 1.26 (0.56, 2.84) 0.574
No 323 (98.2) 128 (97.7) 195 (98.5) 39.6 Ref.
Excluding first sex, ever used sex to get drug/alcohol
Yes 2 (0.6) 1 (0.8) 1 (0.5) 50.0 1.26 (0.31, 5.06) 0.747
No 327 (99.4) 130 (99.2) 197 (99.5) 39.8 Ref.
Excluding first sex, ever used sex to get something else
Yes 11 (3.3) 4 (3.1) 7 (3.5) 36.4 0.91 (0.41, 2.01) 0.817
No 318 (96.7) 127 (96.9) 191 (96.5) 39.9 Ref.
Open in a new tab

yrs. = years; CI = 95% confidence interval (CI); PR = prevalence ratio

a

Analysis sample was restricted to women screened who reported that they had sex within the past 3 months and provided age of first sex. Sample sizes fluctuate slightly for some variables due to missing data.

b

Variables significant at 0.1 level were considered for multivariable analysis.

To minimize the effect of collinearity in the multivariable modeling, we included historical behavior variables or used variable combinations whenever similar recent and/or contemporary behavior variables were available. We used the chi-square test and 0.1 cut-off level to guide the variable selection into a multivariable model, checked for two-way interactions, and applied backward elimination. We also controlled for confounding factors by looking for a meaningful (>10%) change in the mean and standard error regression estimates. The analyses and report generation were performed using SAS System for Windows, version 9.4 (SAS Institute Inc., Cary, NC, USA).

Results

Out of 692 women pre-screened, 463 completed the in-depth behavior and medical screening, with 332 women meeting the criteria for inclusion in the analysis. Among those who did not meet the analysis sample inclusion criteria, 115 (87.8%) reported that they had not had sex in the past 3 months (despite indicating at pre-screening that they had engaged in vaginal sex on more than one episode on different days within the past 30 days), 3 (2.3%) did not provide response to the sex in the past 3 months question, and the remaining 13 (9.9%) women did not report or did not know their age of first sex. The median age was 25 years (IQR 21–28); women aged 18–24 years and 25–29 years accounted for about 50% and 35% of the analysis sample, respectively. The women were predominantly Luo ethnicity (89.1%) and not inherited (74.9%). Among those reporting widow inheritance (n=82), more than half (58.5%) were 25 years of age or younger (data not shown). Over half of the women had completed primary education or less (63.9%), were married (67.1%), or were employed (61.5%) (Table 1). The median age of first sex was 16 years (IQR 14–18), and 40.1% women reported early sex. Regardless of age of first sex, most participants (83.9%) reported that they did not want or were not ready for sex at the time of first sex (Table 2). Overall, an STI (herpes simplex virus type 2, gonorrhea, syphilis, or chlamydia) or bacterial vaginosis was diagnosed in more than half of the participants (69.1%) and 14.2% tested positive for HIV (Table 1).

Table 2:

Age of first sex, by first sex contextual factors (N=332)a, Kisumu contraceptive vaginal ring study, Kisumu, Kenya, 2014

Variable Total
(N=332)
n (col %)		 First sex at ≤15 yrs. (N=133)
n (col %)		 First sex at >15 yrs.
(N=199)
n (col %)		 Prevalence of first sex at ≤15 yrs.
(row %)		 PR ≤15 vs. >15 yrs.
(CI)		 p-value
Age of first partner 0.441
About same age as participant 207 (62.3) 79 (59.4) 128 (64.3) 38.2 Ref.
5 or more years younger 26 (7.8) 13 (9.8) 13 (6.5) 50.0 1.31 (0.86, 2.00) 0.209
5 or more years older 99 (29.8) 41 (30.8) 58 (29.1) 41.4 1.09 (0.81, 1.45) 0.583
Self-assessment of first sex readinessb
Did not want/was not ready 276 (83.9) 120 (90.2) 156 (79.6) 43.5 1.77 (1.08, 2.90) 0.022
Wanted/was ready 53 (16.1) 13 (9.8) 40 (20.4) 24.5 Ref.
Received gifts or favors as part of first sexb
Yes 185 (56.2) 85 (63.9) 100 (51.0) 45.9 1.38 (1.04, 1.82) 0.024
No 144 (43.8) 48 (36.1) 96 (49.0) 33.3 Ref.
Received food or non-alcoholic beverage as part of first sex
Yes 98 (29.9) 44 (33.3) 54 (27.6) 44.9 1.17 (0.89, 1.54) 0.252
No 230 (70.1) 88 (66.7) 142 (72.4) 38.3 Ref.
Received alcohol as part of first sex
Yes 6 (1.8) 3 (2.3) 3 (1.5) 50.0 1.24 (0.55, 2.80) 0.600
No 323 (98.2) 130 (97.7) 193 (98.5) 40.2 Ref.
Received clothing as part of first sexb
Yes 51 (15.5) 28 (21.1) 23 (11.7) 54.9 1.45 (1.09, 1.94) 0.012
No 278 (84.5) 105 (78.9) 173 (88.3) 37.8 Ref.
Received school items as part of first sex
Yes 64 (19.5) 31 (23.3) 33 (16.9) 48.4 1.25 (0.93, 1.68) 0.133
No 264 (80.5) 102 (76.7) 162 (83.1) 38.6 Ref.
Received money as part of first sex
Yes 133 (40.5) 58 (43.6) 75 (38.5) 43.6 1.13 (0.87, 1.47) 0.348
No 195 (59.5) 75 (56.4) 120 (61.5) 38.5 Ref.
Received beauty products as part of first sex
Yes 104 (31.7) 47 (35.6) 57 (29.1) 45.2 1.19 (0.91, 1.56) 0.204
No 224 (68.3) 85 (64.4) 139 (70.9) 37.9 Ref.
Received other gifts as part of first sexb
Yes 85 (25.9) 44 (33.1) 41 (21.0) 51.8 1.41 (1.09, 1.84) 0.010
No 243 (74.1) 89 (66.9) 154 (79.0) 36.6 Ref.
Open in a new tab

yrs. = years; CI = 95% confidence interval (CI); PR = prevalence ratio

a

Analysis sample was restricted to women screened who reported that they had sex within the past 3 months and provided age of first sex. Sample sizes fluctuate slightly for some variables due to missing data.

b

Variables significant at 0.1 level were considered for multivariable analysis.

Univariable analyses

As shown in Table 1, on univariable analysis early sex experience was observed at a greater proportion among women who completed primary education or less compared to those who had secondary education or higher (prevalence ratio, 1.64). Similarly, early sex experience was more common among women who had been inherited (1.53) or had abnormal or non-menstruation-related vaginal bleeding in the past 12 months (1.58). Early sex experience was prevalent among women who reported they did not want or were not ready for sex (1.77), as well as among those who responded that gifts or favors were received as part of their first sex experience (1.38) (Table 2). Of the gifts we specifically inquired about in the study questionnaire, univariable relationship with early sex experience was detected for clothing (1.45) and other type of unspecified gifts (1.41). The unspecified gifts response option excluded food, non-alcoholic beverages, alcohol, school items, money, and beauty products. We looked at these items collectively and individually, but we observed no association with early sex.

Early sex occurred predominantly among women who had ever been victims of physically forced/unwanted sex (1.57) and women who had faced non-sexual physical violence from a sexual partner (1.35) (Table 3). Occurrence of early sex was also more likely among women who experienced physically forced/unwanted sex within the past three months (1.61) (Table 4). As further shown in Table 4, early sex was more widespread among women who reported ever having sexual intercourse during menses (1.39), received money from a sexual partner to take care of their menstrual needs (1.33), or had partners of unknown or positive HIV status within the past 3 months (1.54).

Table 4:

Age of first sex, by behaviors in past three months (N=332)a, Kisumu contraceptive vaginal ring study, Kisumu, Kenya, 2014

Variable Total
(N=332)
n (col %)		 First sex at ≤15 yrs.
(N=133)
n (col %)		 First sex at >15 yrs.
(N=199)
n (col %)		 Prevalence of first sex at ≤15
yrs.
(row %)		 PR ≤15 vs. >15 yrs.
(CI)		 p-value
Alcohol use in past 30 days
Yes 42 (12.7) 17 (12.8) 25 (12.6) 40.5 1.01 (0.68, 1.49) 0.967
No 289 (87.3) 116 (87.2) 173 (87.4) 40.1 Ref.
Intravaginal cleansing in past 3 months
Yes 210 (63.8) 83 (62.9) 127 (64.5) 39.5 0.96 (0.73, 1.26) 0.768
No 119 (36.2) 49 (37.1) 70 (35.5) 41.2 Ref.
Number of male sexual partners in past 3 months
One 264 (82.8) 103 (81.1) 161 (83.9) 39.0 0.89 (0.64, 1.25) 0.514
Two or more 55 (17.2) 24 (18.9) 31 (16.1) 43.6 Ref.
Exchange or transactional sex in past 3 months
Yes 47 (14.2) 22 (16.5) 25 (12.6) 46.8 1.20 (0.85, 1.68) 0.295
No 284 (85.8) 111 (83.5) 173 (87.4) 39.1 Ref.
Physically forced/unwanted sex in past 3 monthsb
Yes 31 (9.4) 19 (14.3) 12 (6.1) 61.3 1.61 (1.18, 2.21) 0.003
No 300 (90.6) 114 (85.7) 186 (93.9) 38.0 Ref.
Any partners of unknown or positive HIV status in past 3 monthsb
Yes 159 (47.9) 78 (58.6) 81 (40.7) 49.1 1.54 (1.18, 2.02) 0.002
No 173 (52.1) 55 (41.4) 118 (59.3) 31.8 Ref.
Last time had sexb
Within the last 7 days 132 (40.0) 61 (45.9) 71 (36.0) 46.2 1.27 (0.98, 1.65) 0.071
More than a week ago 198 (60.0) 72 (54.1) 126 (64.0) 36.4 Ref.
Open in a new tab

yrs. = years; CI = 95% confidence interval (CI); PR = prevalence ratio

a

Analysis sample was restricted to women screened who reported that they had sex within the past 3 months and provided age of first sex. Sample sizes fluctuate slightly for some variables due to missing data.

b

Variables significant at 0.1 level were considered for multivariable analysis.

Multivariable regression analysis

Our multivariable analysis is presented in Table 5. Early sex was independently associated with report of being inherited, receiving gifts or favors as part of first sex, having ever experienced physically forced/unwanted sex, and having partners of unknown or positive HIV status within the past 3 months. Specifically, the proportion of those who had early sex was 49% more prevalent among inherited women (1.49) compared to those who were not inherited and 38% more among women who received gifts or favors as part of first sex (1.38) compared to their counterparts who did not receive any reward at their first sexual encounter.

Table 5:

Age of first sex: adjusted prevalence ratios (N=292)a, Kisumu contraceptive vaginal ring study, Kisumu, Kenya, 2014

Variable aPR ≤15 vs. >15 yrs. (CI) p-value
Ever been inherited
Yes 1.49 (1.16, 1.92) 0.002
No Ref.
Received gifts or favors as part of first sex
Yes 1.38 (1.05, 1.82) 0.022
No Ref.
Type of contraceptive used in past 3 months
Depot medroxy-progesterone acetate (DMPA) injection 0.87 (0.61, 1.24) 0.437
Oral contraceptive pills Ref.
Ever experienced physically forced/unwanted sex
Yes 1.42 (1.11, 1.83) 0.006
No Ref.
Any partners of unknown or positive HIV status in past 3 months
Yes 1.45 (1.11, 1.90) 0.007
No Ref.
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yrs. = years; CI = 95% confidence interval (CI); aPR = adjusted prevalence ratio

a

Analysis sample was restricted to women screened who reported that they had sex within the past 3 months, provided age of first sex, and had no missing responses on the variables in multivariable regression.

Engagement in early sex was 1.42 times as prevalent among women who had ever experienced physically forced/unwanted sex compared to those without such an experience. Also, early sex experience was 45% greater among those who reported having partners of unknown or positive HIV status within the past 3 months (1.45). Early sex experience was not independently associated with any of the biologic outcomes (STI, bacterial vaginosis, HIV, or pregnancy) in multivariable regression analysis.

Discussion

Two out of five women in our study experienced sex at or before the age of 15 years. Our findings further showed four factors associated independently with experiencing early sex: being inherited, receiving gifts or favors as part of first sex, a history of physically forced/unwanted sex, and having had sex with a partner who had unknown or positive HIV status in the past 3 months.

Particular social and economic norms may foster gender inequality which then may cultivate permissions and support for sex at an early age among adolescent girls and young women3. Moreover, inequitable power in sexual relationship can make it challenging for adolescent girls and young women to broach sexual and reproductive topics with their partners much less negotiate condom use or contraception; question partner’s risk behaviors and HIV status; or seek assistance with partner anger, emotional abuse, or violent (physical or sexual) behavior. Financial circumstances may further restrict the degree to which young women can exert control in their sexual relationships17.

Despite delayed timing in age of first sex in African countries, data have shown an increase in premarital sex over the past twenty years18. Nationally, the median age of marriage among women 25–49 years of age in 2014 was 20.2 years; however, 15% had first sexual intercourse by age 15, 50% by age 18, and 71% percent by age 209. Onset of puberty at a younger age and increased delays in age of marriage are thought by some researchers to influence earlier age of first sex, as well as premarital sex among adolescent girls and young women in SSA. A study conducted in Kenya and Ghana showed that a lengthy period of premarital sex is related to the spread of HIV19. Moreover, incompatibilities between actual behavior and societal beliefs about the appropriate age for sexual initiation may create gaps in the delivery of sexual education. A 2011 Kenyan study found that, while 95% of parents were aware of the need to provide sex education to children, almost one-third were concerned that exposure to this educational information would result in children taking part in early sexual activity20. Parents with high receptivity toward parent-child communication on sex in the Families Matter Programme have shown increased HIV dialogue21. Additional research is needed to discern associations between age of first sex and parent-child communication about sex.

In general, research that examines the association between early marriage, which is often used as proxy for age of first sex, and HIV or STIs is limited and findings are mixed; however, ecological data suggests that adolescent girls and young women in SSA who marry at a younger age are at increased risk for HIV infection22. This may appear to contradict the earlier statement that prolonged periods of premarital sex increase HIV sexual risk exposures. Alone or in combination with other behaviors or circumstances, prolonged premarital sex and early marriage may both contribute toward increased HIV risk for adolescent girls and young women. An early marriage spouse may be older by five or more years, infected with HIV or STIs, or may have a history of poor health or high-risk behaviors (e.g., high number of lifetime partners, concurrent partnerships, patronizing sex workers). These partner attributes may increase the chances that a young wife will become HIV infected or that she will become a widow at a relatively young age. While our study did not collect data on age of first marriage for women, especially those who reported that they were inherited, the association between early sex and widow inheritance observed in our study may be explained partially by a younger age of first marriage. Widowhood at a young age may have then led to a traditional or a modern variant of widow inheritance. To restore societal normalcy, a widow is required to undergo a cleansing ritual, following the burial of her husband. In the case of young widows, this is accomplished by obligatory sexual intercourse with a professional cleanser12. Widows who may have contracted HIV from their late husbands pose a risk to their inheriting relatives, while uninfected widows could be at increased risk of HIV from either cleansers or professional inheritors, or their sexual networks. Additional research is needed to better characterize younger widows in this setting. Although our study did not consider relationship stability, inheritance compliance among young widows with a history of early sex may be motivated by psychological and emotional factors not adequately covered in the traditional cultural intentions of widow inheritance and may warrant closer examination. Along with dealing with the emotional grief of losing a spouse, a young widow may not be prepared to handle the psychological stress associated with newfound uncertainty in her social status, identity, custody of children, economic situation, and relocation or new living arrangements. Consequently, a young widow may have limited opportunity, time, or skills to make adjustments of her choosing, especially given the possibility that she could be cast out of her matrimonial home or community without any entitlements to her deceased husband’s estates or held responsible for compromising the wellbeing of her offspring23.

Research findings on transactional sex are often mixed given the challenges with defining what it is and what it is not. Transactional sex has been best described as a type of relationship in which multiple overlapping risk behaviors may occur as opposed to a single risk factor24. Importantly, the provision of gifts and favors by a sexual partner and their acceptance by an adolescent girl or a young woman may be situated within a social exchange system that may outwardly have little to do with a health-risk-based definition of transactional sex. However, where the access to material goods and services is held by a sexual partner, increased dependency and reduced bargaining power are likely for adolescent girls and young women17. Receipt of gifts or favors for sex, not just at first sex, among adolescent girls and young women has been shown to be characteristic of low-income settings, such as Kisumu3. Explanations for participation in transactional sex by adolescent girls and young women in SSA have been centered around three paradigms: (1) sex for basic needs which emphasizes women as subject to exploitation and victims of transactional sex, (2) sex for improved social status which positions women as sexual agents, and (3) sex as a material expression of love which places men as providers in such relationships25. Monetary and non-monetary gifts provided within the context of transactional sex have been shown to range from essential daily needs (food, shelter, school fees, hygiene and menstrual management products, etc.) to luxury/lavish items (cellular phone, clothing, cosmetics, etc.)26. Among adolescent girls and young women in SSA, the prevalence of transactional sex ranges as low as 2%27 to as high as 52%28.

Notably, transactional sex may introduce, exacerbate, or emerge as a consequence of gender inequality, which may increase vulnerability for violence, including sexual violence, and discourage autonomy and empowerment of women regardless of age. Women concerned with losing material support from partners may be less likely to refuse sex, negotiate condoms, be in control of their own reproduction, or have fidelity expectations from such partners29. Adolescent girls and young women may be more inclined to engage in first sex at an earlier age given real or perceived prospects for gifts and other material goods available to them or their family. It is noteworthy that lowered HIV incidence among young African women has been observed with microfinance or cash transfer interventions potentially given their short-term nature and non-material benefits of transactional sexual relationships30.

The association between early sex and physically forced/unwanted sex observed in our study is consistent with findings from a number of other SSA studies31. In Kenya, 18% of women 15–19 years of age and 11% of those 20–24 years of age report forced or coercive first sex32. While a study in three African countries showed that adolescent and adult risky sexual behaviors, including early sex experiences, were linked to childhood sexual and physical abuse33, factors associated with early sex may be confounded or mediated by forced sex. CDC’s Technical Package for Preventing Child Abuse and Neglect provides the best evidence available currently to prevent and reduce child abuse and neglect. Additional research, however, is needed to better understand both feasibility and effectiveness of multimodal approaches to safety planning and harm reduction, especially in settings where economic, social, cultural, health, legal, and other structures may hamper inadvertently women’s safety and well-being.

Although a few US-based studies have examined the subsequent timing of sexual involvement, relationship quality, and other relationship dynamics34, to our knowledge, no SSA studies have looked at the association between early sex and later partner traits. Potential qualitative research could provide further insights on how partnering occurs and whether partner selection is influenced by attributes of the first sex partner.

Poor communication influenced by first sexual experience as well as gender roles and expectations may explain possible later-in-life reluctance to ask about a partner’s HIV status. In addition, early sex may subsequently influence a woman’s impulsivity and sensation-seeking behaviors35 as well as preferences for selecting riskier sexual partners given perceptions that such partners are more adventurous or desirable36. Limited research has been conducted on the relationship context (romantic vs. non-romantic) associated with adolescent early sexual experiences and whether or not it influences subsequent risky behaviors37.

Our findings suggest a lack of association between experiencing early sex and biological outcomes. Other studies have demonstrated that early sex may be neither a ‘risk’ nor a ‘protective’ factor38. Findings from a US-based study suggested that, while early sex and negative biological outcomes were not directly correlated, the relationship between them is likely confounded by other antecedent experiences39, including age of menarche40.

Our study had several limitations. Convenience sampling was used to recruit participants and thus, the women in our study may not be representative of women residing in Kisumu County. We were not able to determine causality of factors associated with early sex experiences. Given that several of the factors we examined may have co-occurred with age of first sex (e.g., physical forced/unwanted sex, transactional sex) and ordering cannot be ascertained, caution is highly warranted in deducing temporal associations. Our data were obtained through inquiries about past experience which are subject to recall bias. Finally, some potentially important variables were not included in our analysis due to low numbers (condom use) or questionnaire omission (relationship solidity, age of marriage, inheritance particulars, sexual relationship with inheritor, age of first pregnancy, or age of menarche). Despite these limitations, this study furthers our understanding of factors known to be associated with early sex as well as important factors that could indirectly measure risky sexual behavior (e.g., unknown or positive HIV status of recent sexual partner).

Ethical Approval

The study was approved by the Scientific and Ethics Review Unit of the Kenya Medical Research Institute (KEMRI), an Institutional Review Board for the United States (US) Centers for Disease Control and Prevention (CDC), and the Kenya Pharmacy and Poisons Board. Women who completed the in-depth screening process received a bar of soap, 500 Kenya Shillings (approximately $5 USD) for transport, feminine sanitary pads, and a treated malaria bed net in accordance with the local research study guidance.

Conclusion

Our results suggest that sexual intercourse before or at age 15 may be associated with greater rates of particular higher sexual risk behaviors. Complex power and gender relations, including compliance with cultural traditions, may influence women’s exposure to sexual risk in our research setting. While our findings may suggest that programs targeted on delaying the onset of sexual activity and providing safe sex skills training and support for those who initiate early sex would be beneficial, additional research is needed. Optimally, initiatives, such as DREAMS (Determined, Resilient, Empowered, AIDS-free, Mentored and Safe)41, can examine and address early sex contextual factors that may be mediating negative health behaviors and may help inform early education and intervention programs needed by adolescent and young women in Kisumu. Additionally, longitudinal studies that evaluate the potential ongoing influence of early sex on behavior as women transition from adolescence to adulthood may be helpful.

Acknowledgements

Funding for this work was supported by the United States (US) Centers for Disease Control and Prevention (CDC) under PN1757, 2014–2015. The study is registered at ClinicalTrials.gov under the identifier NCT02529683. The STROBE guidelines were used to prepare cross-sectional findings and conclusion of this single-arm observational study. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the CDC or the US Department of Health and Human Services. Permission to publish this manuscript has been provided from the Kenya Medical Research Institute (KEMRI) Director. We are first and foremost very grateful to the young women who volunteered to participate in the study and to the Kisumu community health workers who mobilized them. Our sincere gratitude also goes to the KEMRI study staff for successfully implementing the study. Lastly, we thank Drs. Taraz Samandari, Victor Mudhune, and Siobhán O’Connor for their technical guidance and support.

Footnotes

Conflict of Interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References

  • 1.Amo-Adjei J and Tuoyire DA. Timing of sexual debut among unmarried youths aged 15–24 years in sub-Saharan Africa. J Biosoc Sci. 2018;50(2):161–77. [DOI] [PubMed] [Google Scholar]
  • 2.Kothari M, Wang S, Head S, and Abderrahim N. Trends in adolescent reproductive and sexual behavior: a comparative analysis. Calverton, Maryland: ICF International; 2012. Accessed June 11, 2018. Available from: https://www.dhsprogram.com/pubs/pdf/CR29/CR29.pdf. [Google Scholar]
  • 3.Stockl H, Kalra N, Jacobi J and Watts C. Is early sexual debut a risk factor for HIV infection among women in sub-Saharan Africa? A systematic review. Am J Reprod Immunol. 2013;69 Suppl 1:27–40. [DOI] [PubMed] [Google Scholar]
  • 4.Magnusson BM, Nield JA and Lapane KL. Age at first intercourse and subsequent sexual partnering among adult women in the United States, a cross-sectional study. BMC Public Health. 2015;15(1):98. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Lee RLT, Yuen Loke A, Hung TTM and Sobel, H. A systematic review on identifying risk factors associated with early sexual debut and coerced sex among adolescents and young people in communities. J Clin Nurs. 2018;27(3–4):478–501. [DOI] [PubMed] [Google Scholar]
  • 6.Pronyk PL. Policy and programme responses for addressing the structural determinants of HIV. Arlington, VA: USAID’s AIDS Support and Technical Assistance Resources, AIDSTAR-One, Task Order 1, and London: UKAID’s STRIVE research consortium; 2013. Accessed August 2018. Available from: https://aidsfree.usaid.gov/sites/default/files/policy_programme_responses.pdf. [Google Scholar]
  • 7.Goldberg RE. Family instability and early initiation of sexual activity in Western Kenya. Demogr. 2013;50(2):725–50. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Ramjee G and Daniels B. Women and HIV in sub-Saharan Africa. AIDS Research and Therapy. 2013;10(1):30. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 9.Kenya National Bureau of Statistics (KNBS), ICF Macro. Kenya demographic and survey 2014. Rockville: National AIDS Control Council/Kenya, Kenya Medical Research Institute, Population NCF, Development/Kenya; 2015. Accessed April 29, 2019. Available from: https://dhsprogram.com/pubs/pdf/FR308/FR308.pd. [Google Scholar]
  • 10.National AIDS and STI Control Programme. Kenya. Kenya AIDS indicator survey 2012: final report. Nairobi: NASCOP; 2014. Accessed September 23, 2018. Available from: http://nacc.or.ke/wpcontent/uploads/2015/10/KAIS-2012.pdf. [Google Scholar]
  • 11.McLellan-Lemal E, Gust DA, Gvetadze R, Furtado M, Otieno FO, Desai M, Zeh C, Samandari T, Nyagol B and Makanga EM. Characteristics of women screened for a contraceptive intravaginal ring study in Kisumu, Kenya, 2014. Res J Womens Health. 2016;3(1):1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Oluoch EA and Nyongesa WJ. Perception of the rural Luo community on widow inheritance and HIV/AIDS in Kenya: towards developing risk communication messages. Int J Bus Soc Sci. 2013;4(1). [Google Scholar]
  • 13.Nyarwath O The Luo care for widows (Lako) and contemporary challenges. Thought and Practice. 2012;4(1):91–110. [Google Scholar]
  • 14.Perry B, Oluoch L, Agot K, Taylor J, Onyango J, Ouma L, Otieno C, Wong C and Corneli A. Widow cleansing and inheritance among the Luo in Kenya: the need for additional women-centred HIV prevention options. J Int AIDS Soc. 2014;17(1):19010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15.McNutt LA, Wu C and Xue X. Estimating the relative risk in cohort studies and clinical trials of common outcomes. Am J Epidemiol. 2003;157(10):940–3. [DOI] [PubMed] [Google Scholar]
  • 16.Zou G A modified poisson regression approach to prospective studies with binary data. Am J Epidemiol. 2004;159(7):702–6. [DOI] [PubMed] [Google Scholar]
  • 17.Luke N and Kurz K. Cross-generational and transactional sexual relations in sub-Saharan Africa. Washington, DC; 2002. [Google Scholar]
  • 18.Ali MM and Cleland J. Long term trends in behaviour to protect against adverse reproductive and sexual health outcomes among young single African women. Reprod Health. 2018;15(1):136. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Bongaarts J Late marriage and the HIV epidemic in sub-Saharan Africa. Popul Stud (Camb). 2007;61(1): 7383. [DOI] [PubMed] [Google Scholar]
  • 20.Mwakelemu E Factors affecting parents in provision of sex education to adolescents: a survey of Embakasi, Nairobi: University of Nairobi, Kenya; 2011. [Google Scholar]
  • 21.Poulsen M, Miller K, Lin C, Fasula A, Vandenhoudt H, Wyckoff S, Ochura J, Obongo C and Forehand R. Factors associated with parent–child communication about HIV/AIDS in the United States and Kenya: a cross-cultural comparison. AIDS Behav. 2010;14(5):1083–94. [DOI] [PubMed] [Google Scholar]
  • 22.Raj A and Boehmer U. Girl child marriage and its association with national rates of HIV, maternal health, and infant mortality across 97 countries. Violence Against Women. 2013;19(4):536–51. [DOI] [PubMed] [Google Scholar]
  • 23.Gunga SOJT, Practice. The politics of widowhood and re-marriage among the Luo of Kenya. 2009;1(1):165–78. [Google Scholar]
  • 24.Joint United Nations Programme on HIV/AIDS and STRIVE. Transactional sex and HIV risk: from analysis to action. Geneva: UNAIDS; Accessed December 17, 2018. Available from: http://www.unaids.org/sites/default/files/media_asset/transactional-sex-and-hiv-risk_en.pdf. [Google Scholar]
  • 25.Stoebenau K, Heise L, Wamoyi J and Bobrova N. Revisiting the understanding of “transactional sex” in sub-Saharan Africa: A review and synthesis of the literature. Soc Sci Med. 2016;168:186–97. [DOI] [PubMed] [Google Scholar]
  • 26.Leclerc-Madlala S Transactional sex and the pursuit of modernity. Soc Dyn. 2003;29(2):213–33. [Google Scholar]
  • 27.Steffenson AE, Pettifor AE, Seage III GR, Rees HV and Cleary PD. Concurrent sexual partnerships and human immunodeficiency virus risk among South African youth. Sex Transm Dis 2011;38(6):459. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28.Juma M, Alaii J, Bartholomew LK, Askew I and Van den Borne B. Risky sexual behavior among orphan and non-orphan adolescents in Nyanza Province, Western Kenya. AIDS Behav. 2013;17(3):951–60. [DOI] [PubMed] [Google Scholar]
  • 29.Nkosana J and Rosenthal D. The dynamics of intergenerational sexual relationships: the experience of schoolgirls in Botswana. Sex Health. 2007;4(3):181–7. [DOI] [PubMed] [Google Scholar]
  • 30.Mojola SA and Wamoyi JJ. Contextual drivers of HIV risk among young African women. J Int AIDS Soc. 2019;22:e25302. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Shamu S, Munjanja S, Zarowsky C, Shamu P, Temmerman M and Abrahams N. Intimate partner violence, forced first sex and adverse pregnancy outcomes in a sample of Zimbabwean women accessing maternal and child health care. BMC Public Health. 2018;18(1):595. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Decker MR, Latimore AD, Yasutake S, Haviland M, Ahmed S, Blum RW, Sonenstein F and Astone NM. Gender-based violence against adolescent and young adult women in low-and middle-income countries. J Adolesc Health. 2015;56(2):188–96. [DOI] [PubMed] [Google Scholar]
  • 33.Richter L, Komarek A, Desmond C, Celentano D, Morin S, Sweat M, Chariyalertsak S, Chingono A, Gray G, Mbwambo J and Coates T. Reported physical and sexual abuse in childhood and adult HIV risk behaviour in three African countries: findings from Project Accept (HPTN-043). AIDS Behav. 2014;18(2):381–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.Sassler S, Addo FR and Lichter DT. The tempo of sexual activity and later relationship quality. J Marriage Fam. 2012;74(4):708–25. [Google Scholar]
  • 35.Kahn JA, Kaplowitz RA, Goodman E and Emans S J. The association between impulsiveness and sexual risk behaviors in adolescent and young adult women. J Adolesc Health. 2002;30(4):229–32. [DOI] [PubMed] [Google Scholar]
  • 36.Henderson VR, Hennessy M, Barrett DW, Curtis B, McCoy-Roth M, Trentacoste N and Fishbein M. When risky is attractive: sensation seeking and romantic partner selection. Pers Individ Differ. 2005;38(2):311–25. [Google Scholar]
  • 37.Harden KP and Mendle J. Adolescent sexual activity and the development of delinquent behavior: the role of relationship context. J Youth Adolesc. 2011;40(7):825–38. [DOI] [PubMed] [Google Scholar]
  • 38.Harden KP, Mendle J, Hill JE, Turkheimer E and Emery RE. Rethinking timing of first sex and delinquency. J Youth Adolesc. 2008;37(4):373–85. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 39.Epstein M, Bailey JA, Manhart LE, Hill KG and Hawkins JD. Sexual risk behavior in young adulthood: broadening the scope beyond early sexual initiation. J Sex Res. 2014;51(7):721–30. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Glynn JR, Kayuni N, Floyd S, Banda E, Francis-Chizororo M, Tanton C, Molesworth A, Hemmings J, Crampin AC and French N. Age at menarche, schooling, and sexual debut in northern Malawi. PLoS One. 2010;5(12):e15334. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Mathur S, Okal J, Pilgrim N, Matheka J, Jani N and Pulerwitz J. “DREAMS implementation science: phase 1 analysis data, Kenya. Harvard Dataverse, V1. 2018. Accessed December 12, 2019. Available from 10.7910/DVN/AHHXBI. [DOI] [Google Scholar]

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