Teenage pregnancy accounts for more than 750,000 pregnancies each year, of which 82% are unintended.1 A large percentage of unplanned pregnancies (64%) also occur among women aged 20–24 years.1 Despite the growing acceptance of long-acting reversible contraceptive (LARC) methods, the most common forms of contraception used by teenagers are the male condom, withdrawal, and the oral contraceptive pill (OCP).2 Previous research indicates that teenagers are more likely to experience method failure with OCPs than women older than 30 years of age, and they also are less likely to adhere to a daily pill regimen.3–5
Because of high rates of unintended pregnancy and low use of the most effective methods of contraception, teenagers and young women represent an important group who may benefit from LARC methods. The intrauterine device (IUD) and subdermal etonogestrel implant have been shown to be extremely effective in preventing unwanted pregnancy, with pregnancy rates of 0.05–0.8% during the first year of use.6 The typical-use and perfect-use failure rates are almost identical for LARC methods in comparison with OCPs and the male condom.6 Despite their high level of effectiveness, LARC methods are used by only a small percentage of women in the United States, and by an even smaller percentage of teenagers and young adults. One study found that only 1.7% of females aged 15–24 years had ever used an IUD7; another reported that 4.5% of females aged 15–19 and 8.3% of women aged 20–24 years currently use LARC methods.8
Many experts recommend that LARC methods should be first-line contraceptive options for all women, including teenagers.9–11 Multiple studies have shown LARC methods to be acceptable and safe in young women,10–16 but there are no large-scale studies examining the effect of age on continuation rates. The purpose of this analysis was to examine the effect of age on contraceptive continuation rates in teenagers and young women enrolled in the Contraceptive CHOICE Project. Our hypothesis was that continuation rates among LARC users would not be affected by age, whereas young age would be associated with higher discontinuation in those using non-LARC methods (ie, OCP, patch, ring, and depot medroxyprogesterone acetate [DMPA]).
MATERIALS AND METHODS
The Contraceptive CHOICE Project is a prospective cohort study of 9,256 female participants in the St. Louis region. A more detailed description of the methodology of the CHOICE Project has been previously described.17 Before initiation of recruitment, the CHOICE protocol was approved by the Washington University in St. Louis School of Medicine Human Research Protection Office. We briefly describe the project and analyses relevant to the present study.
The primary objectives of CHOICE are to: remove all financial barriers to contraceptive methods; promote the use of the most effective methods of contraception (IUDs and implants); and reduce unintended pregnancies in the St. Louis region. The study sample is a convenience sample of participants recruited from university-affiliated clinics, facilities providing abortion services, community clinics, and through word of mouth. Inclusion criteria for CHOICE are: age 14–45 years; no desire for pregnancy in the next year; willing to switch or initiate a new contraceptive method; sexually active with a male partner in the past 6 months or anticipate sexual activity in the next 6 months; and reside in St. Louis city or county or seek clinical services in designated recruitment sites in the St. Louis region. To be included in this analysis, participants had to initiate their baseline chosen contraceptive method within 3 months of enrollment and reach the time point for their 12-month follow-up survey. Only the participant’s initial contraceptive method was included in this analysis.
All participants were read a script that emphasized that IUDs and implants are the most effective reversible contraceptive methods at the time of screening for study eligibility.17 Participants then underwent contraceptive counseling that included information about all Food and Drug Administration--approved reversible methods. The majority of this counseling was performed by research assistants who were trained contraceptive counselors at the university-based recruitment site. The remainder was performed by clinic staff or health care providers or both at the clinical facility providing the counseling.17,18 Each participant was offered no-cost reversible contraception for 2–3 years (depending on the date of enrollment). Sexually transmitted infection (STI) testing was performed after a face-to-face, standardized baseline survey. All participants were counseled about the risk of STIs and encouraged to use condoms if they were at risk. Participants were then followed-up with telephone interviews at 3 and 6 months, and every 6 months for the duration of follow-up.
During each follow-up telephone survey the participant was asked, “are you still using the method?” If yes, then she was asked, “did you ever stop using the method?” A “continuer” was a participant who reported using her baseline method at the 3-, 6-, and 12-month surveys without a temporary stop of 1 month or longer. A “discontinuer” was a participant who was not using her baseline method at any of the survey time points or who reported stopping her method for 1 month or longer. When participants missed a survey or completed the survey without answering the method use question, we used additional data sources. Among LARC users, we used our contraceptive method allocation and removal log to confirm method use. Participants who were recorded saying they had their IUD or implant removed in the removal log were considered “discontinuers.” For participants who experienced an expulsion of an IUD, replacement was offered. If the IUD was replaced within 1 month, this was considered a continuer, whereas, if the participant elected an alternative form of contraception after expulsion, she was considered a discontinuer. For those who used DMPA, OCPs, patch, or the ring, we used the method allocation log and pharmacy refill records to verify their method use. Participants who were lost to follow-up were censored at their last completed survey date.
We stratified participants by age group (14-19, 20-25, and 26 years and older). Continuation rates were then assessed by age within each method group: LARC (IUD and implant) and non-LARC (OCPs, DMPA, patch, or ring) users. Demographic characteristics of the study participants were described using frequencies, percentages, means, and standard deviations when appropriate. We compared baseline characteristics using χ2 or Fisher exact tests when appropriate for categorical variables, and Student t test was used for normally distributed continuous variables. Normality was assessed by evaluating the histogram of continuous variables. We used Kaplan-Meier survival curves to estimate continuation rates, and hazard ratios of discontinuation were estimated using Cox proportional hazard models.
We also compared user satisfaction at 12 months. There were three levels of satisfaction: “very satisfied;” “somewhat satisfied;” and “not satisfied.” All discontinuers were considered not satisfied. We grouped very satisfied and somewhat satisfied participants together and compared them with not satisfied participants to determine satisfaction at 12 months. We also performed univariable and multivariable Poisson regression with robust error variance to assess factors associated with satisfaction. Poisson regression with robust error variance allows for a conservative estimate of the relative risk (RR) when the outcome of interest occurs more than 10% of the time, as was the case with user satisfaction.19 Confounding was defined as a more than 10% relative change in the association between continuation or satisfaction and age groups with or without the covariate of interest in the model. All the confounding factors were included in the adjusted multivariable model (education, gravidity, history of STI). Analyses were performed using STATA 11. The significance level alpha was set at 0.05.
Among 9,256 participants enrolled in CHOICE Project between August 2007 and September 2011, 7,472 met the inclusion criteria and are included in this analysis. Table 1 presents baseline characteristics of the analytic sample by age group. Participants who were 14–19 years old were more likely to be black and to report trouble paying for basic expenses, and were less likely to be uninsured than participants in the older groups. Participants in the youngest age group also were more likely to be nulliparous and less likely to have experienced an unintended pregnancy or an STI.
The 12-month LARC continuation rates were more than 75%, and were higher than non-LARC methods for all age groups as shown in Table 2. The LARC continuation ranged from 81% in 14- to 19-year-olds to 86% in women older than 25 years. The levonorgestrel intrauterine system had the highest 12-month continuation rate (86–87%) in both the 20- to 25-years age group and 26 years and older age group. Participants 26 years old and older reported LARC continuation rates more than 84% (levonorgestrel intrauterine system 86%, copper IUD 86%, and implant 84%). Non-LARC method continuation was 44% for 14- to 19-year-olds and 53% in the oldest group. Females (14–19 years) who used the ring reported the lowest 12-month continuation rate (31%), whereas women aged 20–25 years and 26 years and older reported the lowest continuation with the contraceptive patch (40% and 41%, respectively).
Table 3 provides satisfaction rates at 12 months by contraceptive method stratified by age. Loss to follow-up at 12 months was 6%. Satisfaction rates were higher for LARC users regardless of age (75% for age 14–19 years, 82% for age 20–25 years, and 83% for age 26 years and older) compared with non-LARC users (42% for age 14–19 years, 50% for age 20–25 years, and 51% for age 26 years and older). Females aged 14–19 years reported the highest rates of being not satisfied with the ring (69%), patch (65%), DMPA (57%), and OCPs (54%). Participants aged 14–19 years were less likely to be satisfied overall with non-LARC methods (adjusted RR 0.80, 95% confidence interval 0.65–98), but this difference was not seen with LARC methods (adjusted RR 0.94, 95% confidence interval CI 0.88–1.01). The differences observed in satisfaction were small and may not be clinically significant.
Among participants in the Contraceptive CHOICE Project, we found that females aged 14–19 years had lower continuation rates of non-LARC methods when compared with older women. We found little difference in the continuation rates of LARC methods by age group; more than 75% of participants of all ages were still using their LARC method at 12 months.
We noted slightly lower continuation rates among adolescents using the copper IUD when compared with older women (76% compared with 86%). However, this difference was not statistically significant. We had limited power to detect differences by age group in copper IUD users because of the small number of participants aged 14–19 years using the copper IUD (n=55).
The youngest age group expressed slightly less satisfaction with all contraceptive methods compared with older women. Participants aged 14–19 years using OCPs, the patch, ring, or DMPA had the lowest satisfaction rates, with more than half being not satisfied. Dissatisfaction was especially true for the patch (65%) and the ring (69%). In 2008, Creinin et al20 performed a randomized controlled trial comparing 3-month continuation rates of the patch compared with the ring. They found that 3-month continuation of the ring was higher than the patch (95% compared with 88%; P=.03). However, when asked whether participants intended to continue use of their assigned method after study completion, only 71% and 26% reported intent to continue the ring and patch, respectively.
The finding that participants aged 14–19 years are less likely to continue non-LARC methods is consistent with previous studies. Raine et al21 conducted a 12-month longitudinal cohort study of 1,387 females aged 15–24 years using OCPs, patch, ring, and DMPA for contraception. Continuation was independently associated with method type and younger age (lower continuation in younger participants). Continuation was lowest for the patch and DMPA. LARC methods were not included in this report.
Little evidence is available regarding continuation and satisfaction with IUDs in teenagers and young women,11 and data are especially sparse with regard to the copper IUD. Rasheed et al22 conducted a prospective cohort study of 281 females 13–19 years of age and 571 older women (age 20–30 years) at a family planning clinic who underwent placement of the copper IUD. This study included only primiparous women who had an IUD placed 6–8 weeks after delivery and had a fairly high rate of loss to follow-up (21% completed follow-up at 6 months). At 1 month after insertion, they noted that females 13–19 years of age had higher rates of pain, bleeding, displacement, expulsion, and removal than older women. At 6 months, females 13–19 years of age had equivalent rates of removal compared with older women. Godfrey et al14 conducted a small pilot study randomizing females aged 14–18 years to the levonorgestrel intrauterine system or the copper IUD. They found 6-month continuation rates of 75% for the levonorgestrel intrauterine system and 45% for the copper IUD. This study was limited by its small sample size (n=23). Additional studies evaluating the copper IUD in young women are needed.
Overall, 12-month continuation rates for the etonogestrel implant range between 75% and 91%.23–25 A study comparing continuation and satisfaction between women using either the levonorgestrel intrauterine system or the etonogestrel implant found similar 6-month continuation rates at 89% and 83%, respectively.26 However, satisfaction was lower among implant users (74% and 58%, respectively; P=.002). This study did not stratify their population by age and did not specifically evaluate teenagers. In fact, there are few studies evaluating continuation of the etonogestrel subdermal implant in adolescents. A prospective observational study of 171 females aged 13–24 years who received immediate postpartum implants found that 86% were still using the implant at 12 months.27 Repeat pregnancy rates at 12 months were significantly lower among implant users at 3% compared with 19% among users of other contraceptive methods. The generalizability of these results is limited by the exclusively postpartum adolescent population. In a previous CHOICE analysis, we found that teenagers (age 14–17 years) were more likely to favor the implant over the IUD compared with women between 18 and 20 years of age.12 These findings suggest that adolescents may prefer the implant for long-acting and highly effective contraception.
The strengths of our study include its large sample size, prospective design, low rate of loss to follow-up at 12 months (6%), and evaluation of all forms of reversible contraception. Limitations of our study include our requirement that participants start a new contraceptive method, utilization of a convenience sample, and recruitment limited to the St. Louis region, which may limit the generalizability of our findings. Another potential limitation of our study is that continuation was self-reported and therefore subject to reporting bias. In addition, methods were provided at no cost, which could have resulted in higher continuation of refillable methods (OCPs, patch, ring) and DMPA. However, our 12-month continuation rates for these methods are comparable with other reports.21,28–31
Teenagers and young women represent a population at especially high risk for STIs. Barrier methods are the best way to prevent STIs, and clinicians should continue to encourage condom use for STI prevention. An ideal approach in counseling teenagers and young women should emphasize dual method use, utilizing reliable contraception for pregnancy prevention and condom use to prevent STIs.
Given the high rates of continuation and satisfaction of LARC methods among teenagers and young women, LARC should be offered to as first-line contraceptive options to adolescent girls and women of all ages to effectively prevent unintended pregnancies.32
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