Research has shown that providing contraception at no cost and educating adolescents and women about the most effective contraceptive methods can decrease unintended pregnancy rates and abortion.1,2 These important findings from the Contraceptive CHOICE Project in St. Louis, Missouri, were covered widely by the news media.3-5 Leaders in Congress and the White House have stated, “broadening access to birth control will help reduce the number of unintended pregnancies and abortions.”6
Although the medical community acknowledges the benefits of increased access to effective contraception,7-9 others in society are less enthusiastic. The Family Research Council, for example, has raised concerns that increased access to contraception may actually lead to an increase in the number of unintended pregnancies, presumably by increasing sexual activity.5 An article in the American Thinker states, “The results are in: contraception availability does not reduce unintended pregnancies. Studies have shown that contraception increases sexual activity—ie, that more contraception means more sex.”10
The question of whether increased access to contraception changes sexual behavior in unanticipated ways is an important one. Reliance on data rather than intuition is advisable. The purpose of this report is to estimate whether provision of no-cost contraception is associated with a change in the number of sexual partners and frequency of intercourse over time among participants enrolled in a large study of reversible contraception.
MATERIALS AND METHODS
This is a secondary analysis of data collected from participants enrolled in the Contraceptive CHOICE Project. CHOICE is a prospective cohort study of 9,256 reproductive-aged adolescents and women that provides all forms of reversible contraception at no cost in an effort to reduce unintended pregnancy. A detailed description of the study has been previously published.11 The cohort is a convenience sample recruited through provider referral, word of mouth, and study flyers.
Eligible participants were residents of St. Louis or sought clinical services at a study recruitment location; 14–45 years of age; willing to start a new method of reversible contraception or not currently using a contraceptive method; interested in avoiding pregnancy for at least 1 year; sexually active with a male partner in the past 6 months or planning to have sex within the next 6 months; and English-speaking or Spanish-speaking. Participants were excluded if they had a hysterectomy or sterilization procedure. Participants were provided with structured contraceptive counseling at enrollment by a trained counselor who reviewed each method and its effectiveness, benefits, risks, and side effects.12 Once approved by a clinician, participants were provided with their contraceptive method of choice. Participants were allowed to change methods during the study. During the baseline enrollment session, participants responded to a staff-administered questionnaire and completed sexually transmitted infection (STI) screening. The questionnaire collected demographic information and reproductive and sexual histories. Participants were followed-up for 2–3 years and completed telephone surveys at 3 and 6 months and every 6 months thereafter for the duration of their participation. The study was approved by the Washington University Human Research Protection Office and written informed consent was obtained from study participants before enrollment.
In this analysis we examined two measures of sexual risk related to pregnancy and STI among reproductive-aged women and adolescents: number of sexual partners and frequency of intercourse. Having multiple sexual partners, either concurrent or sequential during a specified period of time, is a known sexual risk behavior.13-15 Transmission of STIs is dependent on the number of sexual partners and sex acts per partner; increases in one or both enhance the likelihood of persistence of the infection in a community.16
We included participants who completed both 6-month and 12-month surveys. To compare the number of male sexual partners and coital frequency during a 30-day recall period assessed at baseline, 6 months, and 12 months, we used the following three questions: during the past 30 days, how many men have you had vaginal sex with?; during the past 30 days how many times did you have sex with your main (or steady) male partner?; and, among women who reported multiple partners during the past 30 days, how many times did you have sex with your other male partner(s)?
Means, standard deviations, frequencies, and percentages were used to describe the characteristics of participants in the analysis and excluded samples. For the comparison of the excluded and analytic samples in Table 1, we used a chi-square test for categorical data and Student t test or Wilcoxon Mann-Whitney test for continuous variables when appropriate. We present the distribution of male sexual partners during the past 30 days at baseline, 6 months, and 12 months. The change in number of partners during the past 30 days from baseline to 6 month and 12 months is shown as the percent of participants who reported a decrease, no change, or an increase in the number of male sexual partners. We focus on the difference between more than one sexual partner compared with zero or one sexual partner, because participants in the study were seeking contraception and therefore would be expected to be sexually active, and because of the additional sexual risk that comes with multiple partners. We also present the distribution of coital frequency during the past 30 days and the change from baseline to 6 months and 12 months as the percent of participants who reported a decrease, no change, or an increase. We stratified an increase in acts into two categories of one to seven acts or eight or more acts from baseline to each survey time point. We used the cut-off of seven acts based on the baseline mean number of acts during the past 30 days. Generalized estimating equations were used to test for the trend over time in the percent of participants who reported multiple partners. Because the number of partners and acts of intercourse were not normally distributed, the Wilcoxon signed-rank test was used to compare the change from baseline to 6-month and 12-month time points. The Stuart-Maxwell test was used to test whether the distribution of change at 6 months was equivalent to the change observed at 12 months. All analyses were performed using Stata 11. P<.05 was considered statistically significant.
Of the 9,256 participants enrolled in CHOICE, 7,751 (84%) completed their 6-month and 12-month surveys and were included in this analysis. Eight percent at each time point did not complete their 6-month (n=777) or 12-month (n=728) surveys. Table 1 compares the baseline demographic and reproductive characteristics of the analysis sample to those of the participants not included in the analysis. Although there was no difference in the mean number of partners during the past 30 days (P=.11), participants in the excluded group were more likely to be younger than 20 years of age, to be black, to have reported less education, to receive public assistance or public insurance, to have a greater number of unintended pregnancies, fewer lifetime sexual partners, and to test positive for a STI at baseline.
We observed a statistically significant decrease over time in the percent of participants who reported multiple partners during the past 30 days. At baseline, 5.2% reported more than one male sexual partner compared with 3.5% and 3.3% at 6 months and 12 months, respectively (P<.01). Table 2 presents the change in number of male sexual partners during the past 30 days over time. The median number of sexual partners was identical at all three time points (median, 1). Most participants (70–71%) reported no change in the number of sexual partners at 6 months and 12 months, whereas 13–14% reported a decrease and 16% reported an increase (P<.01). Among the 16% of participants who reported an increase in the number of partners, more than 80% had an increase from no partners to one partner. The overall distribution of change in male partners during the past 30 days was similar at 6 months and 12 months (P=.11).
We observed an increase in the frequency of sexual intercourse during the past 30 days from baseline to 6 and 12-month time points (<0.01) (Table 2). The median frequency increased from four episodes at baseline to six episodes at 6 months and 12 months. Half of the study participants reported an increase in the frequency of sexual intercourse during the past 30 days from baseline to 6 months and 12 months, with the other half reporting either no change or a decrease. In addition, the distribution of change in the frequency of intercourse reported at 6 months was different than that reported at 12 months (P<.01). We compared the combined incidence rate of Chlamydia trachomatis and Neisseria gonorrhoeae infection at 12-month follow-up between participants who reported the same or fewer acts of intercourse to that of participants who reported an increase and found similar rates in both groups (3.6/100 woman-years compared with 4.2 per 100 woman-years respectively; P=.16).
The percentage of women who reported multiple partners during the past 30 days declined modestly from baseline to both 6 months and 12 months. The majority of participants who reported an increase in partners were those who reported no partners during the past 30 days at baseline and subsequently reported only one partner at 6 months or 12 months. This finding was not unexpected given that our study inclusion criteria required current sexual activity with a male partner or intention to be sexually active in the next 6 months. Of note, at enrollment 95% of participants who had zero partners during the past 30 days reported a history of sexual intercourse. Among the 96 participants who reported never having had intercourse at enrollment, 52% reported no partners at 6 months and 46% reported no partners at 12 months. Previous research among nationally representative samples reported that the majority of participants (69%) had one male sexual partner in the past year, whereas 8% reported two partners, 3% reported three partners, and 3% reported four or more partners.17 Adimora et al15 estimated that 8% of United States women reported concurrent sexual partners during the past 12 months and found concurrency was associated with several factors, including younger age, black race, and younger age at first intercourse. Teenagers (15–19 years) and younger women (20–24 years) are more likely to report more than one male sexual partner during the past 12 months compared with women aged 25 and older (19%, 24%, and 9%, respectively).17
We observed an increase of two episodes of sexual intercourse from baseline to 6-month and 12-month time points during the previous 30-day period. The clinical significance of this increase is unclear. However, we did not find a difference in the STI incidence rate at 12 months between participants who reported the same or fewer acts of intercourse to participants who reported an increase. In addition, the overall average coital frequency reported during the past month among participants enrolled in the CHOICE Project (8.6 acts) was comparable to that reported among a 2002 national probability sample of sexually experienced women aged 25–45 years (6.4 acts).18 The 2002 national sample has a higher mean age, and age is inversely related to sexual activity; thus, the higher mean coital frequency in our sample is expected.
A major strength of our study was the use of a large cohort of sexually active females of reproductive age, including more than 4,000 females aged 14–24 years who are at increased risk for STI and unintended pregnancy. We examined two measures of sexual risk at multiple points subsequent to access to no-cost contraception. Our study did not obtain detailed information on the start and end times of each relationship reported during the surveys; therefore, we are unable to examine the length of overlap or time between multiple partners. Such an analysis would be important to fully understand the risk of STI transmission.14 Our findings are susceptible to recall bias in the number of partners reported at 6 months and 12 months and hesitancy among participants to disclose multiple partners for fear of judgment, especially among young women and adolescents.19 Although the excluded group may be at higher risk for STIs and unintended pregnancy than the analytic sample, which may underestimate the behavior change found in our analysis sample, the remaining 84% of the total cohort included in the analysis were also at high risk. Furthermore, participants in our analytic sample were younger, more likely to be black, to be unmarried, to have a younger age of sexual debut, and to be more likely to have experienced an unintended pregnancy than females surveyed in the National Survey of Family Growth.17,18 Although the generalizability of our data may be a limitation, we believe our findings apply to females at greatest risk for STIs and unintended pregnancy.
We have shown previously in this cohort that provision of no-cost contraception results in greater use of the most effective contraceptive methods (intrauterine device and implant),2 which results in fewer unintended pregnancies, including births to teenagers, and abortions.1 Overall, we found little evidence to support concerns of increased sexual risk-taking behavior subsequent to greater access to no-cost, highly effective contraception.
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