Unintended pregnancies and teen births are major public health concerns, and rates in the United States are among the highest in industrialized nations.1 Long-acting reversible contraception (LARC), comprising subdermal implants and intrauterine devices (IUDs), offers women the most effective protection against pregnancy coupled with high continuation rates and affordability,2,3 yet only 5% of sexually active adolescents using contraception have an IUD and fewer have a contraceptive implant.4
Health care provider misconceptions about the safety of IUDs, particularly for young nulliparous women, are prevalent and contribute to their low uptake.5 Experts including the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics endorse LARC methods as first-line contraceptive options for all women including adolescents.6 Nonetheless, attitudes are changing slowly; a 2010 survey showed health care provider misconceptions about the safety of IUDs for nulliparous women and adolescents remain a barrier with only 62% reporting they would consider an IUD for a nulliparous patient and 31% for a teenager.7
There is a paucity of information to support the expansion of LARC use in nulliparous adolescents.8 We previously reported that more than 80% of adolescents continue their LARC method at 12 months.9 Studies of LARC use in postpartum adolescents observed similarly high implant continuation rates but lower IUD continuation rates at 55%.10,11 The purpose of this study is to extend our previous analyses to assess the relationship between age–parity groups and LARC method continuation. We hypothesized that nulliparous participants aged 14–19 years would be most likely to discontinue their LARC method.
MATERIALS AND METHODS
We performed a secondary analysis of the Contraceptive CHOICE Project database, an observational cohort study of 9,256 participants. A detailed description of the Contraceptive CHOICE Project methods was reported previously.12 In the Contraceptive CHOICE Project, comprehensive contraceptive education was provided, and access and financial barriers to contraceptive methods were removed. This analysis focused on continuation of the IUD and implant in nulliparous participants aged 14–19 years compared with parous, older participants.
The primary goal of the Contraceptive CHOICE Project was to inform a large number of women in the St. Louis region regarding the superior effectiveness of the intrauterine device and subdermal implant compared with other contraceptive methods. The three LARC methods used in the Contraceptive CHOICE Project were the 52-mg levonorgestrel intrauterine system, copper IUD, and subdermal etonogestrel implant. Participants were permitted to choose any U.S. Food and Drug Administration-approved contraceptive method and switch methods at any time during their participation in the study (2–3 years). The Human Research Protection Office at Washington University School of Medicine approved the Contraceptive CHOICE Project protocol before participant recruitment began.
The Contraceptive CHOICE Project study population was a convenience sample of females in the St. Louis region recruited between August 2007 and September 2011 from word of mouth, referral from medical providers, newspaper advertisements, and study flyers. Recruitment sites included a university-affiliated clinic, two abortion facilities, and community clinics in our region. Those who met the following inclusion criteria were eligible: 1) age range: 14–45 years, 2) English- or Spanish-speaking, 3) heterosexual activity in the past 6 months or anticipated activity in the next 6 months, 4) desire to avoid conception in the next year, and 5) willing to try a new reversible contraceptive method (or not currently using a method). Only participants who chose IUD or implant at enrollment and initiated their chosen method within the first 3 months were included in this secondary analysis.
Participants underwent contraceptive counseling that included a script emphasizing the effectiveness of the implant and IUDs.13 Research assistants, clinic counselors, staff, or health care providers provided information about all Food and Drug Administration-approved reversible methods. After written informed consent was obtained, participants completed a structured survey and were screened for sexually transmitted infections (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis). Telephone interviews were conducted at 3 and 6 months and every 6 months for the duration of study participation; data collected included method use, satisfaction with method, complications, and possibility of pregnancy.
We considered a participant a “continuer” at 12 and 24 months if the participant reported using her baseline method at the 3-, 6-, and 12-month surveys and at the 18- and 24-month surveys, respectively, without a temporary stop of 30 days or longer. A participant was considered a “discontinuer” if she was no longer using her baseline method at any of the survey time points or reported stopping her method for 1 month or longer. We used additional data sources when participants missed a survey or completed the survey without answering the continuation question. We used our contraceptive method allocation and removal log to confirm LARC method use. If an expulsion of an IUD occurred, replacement was offered. If replaced within 1 month, the participant was considered a “continuer.” If an alternative method was chosen, the participant was considered a “discontinuer.” For those who used oral contraceptive pills, patch, ring, or depot medroxyprogesterone acetate, we used the method allocation log and pharmacy refill records to verify their method use. Participants who were lost to follow-up or who reported method discontinuation to attempt pregnancy were censored at their last completed survey date or time when they discontinued the method.
We stratified participants by age and parity (14–19, 20–25, and 26 years and older; nulliparous compared with parous) and by age–parity groups (younger than 20 years and nulliparous; younger than 20 years and parous; 20–25 years and nulliparous; 20–25 years and parous; older than 25 years and nulliparous; older than 25 years and parous [referent group]). Participants aged 14–19 years were considered adolescents. Continuation rates of LARC methods were assessed by age and parity and in a separate analysis by age–parity group. We described demographic characteristics of participants using frequencies, percentages, means, and standard deviations where appropriate. Baseline characteristics were compared using χ2 or Fisher's exact tests for categorical variables and Student's t test for normally distributed continuous variables. Kaplan-Meier survival curves were used to estimate continuation rates, the log-rank test was used to compare differences among age–parity groups overall and stratified by LARC method, and hazard ratios were estimated using Cox proportional hazard models. Effect modification was evaluated by including the interaction term in the model. The stratified analyses were conducted when significant effect modification was identified. To evaluate the risk factors for method discontinuation, the potential confounding factors were included in the Cox proportional hazard model to get the estimates of adjusted hazard ratios. STATA 11 was used for statistical analyses, and the significance level α was set at .05.
Of the 9,256 adolescents and women enrolled in the Contraceptive CHOICE Project, 6,106 participants chose an IUD or implant at enrollment and initiated their chosen method within the first 3 months. Of these 6,106 participants, 3,699 (61%) received the levonorgestrel intrauterine system, 1,433 (23%) the implant, and 974 (16%) the copper IUD (Table 1). Our study sample was a diverse representation of reproductive-aged females in many respects: 58% (3,519) were 25 years or younger, 42% (2,537) were nulliparous, 49% (2,997) were black, and 5% (328) were of Hispanic ethnicity. There were 863 (14%) participants aged 14–19 years in our analytic set. Of this group, 71% (614) were nulliparous, 49% (425) chose IUDs, and 51% (438) chose the implant. Among all nulliparous females (regardless of age), IUDs were preferred above implants, 73% (1,860) compared with 27% (677).
Table 1 also compares baseline characteristics of the analytic sample by LARC method group. Differences were observed in age, parity, race and socioeconomic parameters between users of individual LARC methods. Young age, nulliparity, black race, lower income, public insurance, and single marital status were associated with implant use.
Table 2 shows the specific 12- and 24-month continuation rates for each age–parity group overall and stratified by method. The median number of months to LARC discontinuation was either 23 or 24 months per age–parity status. Twelve-month continuation rates for LARCs were high and similar for each age–parity stratum: rates ranged from 82–86%. When further stratified by LARC method, continuation rates were 86% for both IUDs in parous women 20 years of age and older. The highest 12-month continuation rate 92% (95% confidence interval [CI] 85–96) was found among parous participants (14–19 years of age) using the implant and the lowest continuation rate 75% (95% CI 69–80) was observed in nulliparous implant users aged 20–25 years. We extended our analysis to 24 months and found the high rates of LARC continuation persisted. Sixty-six percent of nulliparous participants aged 14–19 years (95% CI 62–69) were using their method at 24 months, and continuation rates in parous women 26 years and older was highest at 76% (95% CI 74–78).
We evaluated the interaction between age and parity, interaction between method and age, and between method and parity. We found a significant interaction between method and parity only. Table 3 presents demographic and reproductive risk factors for LARC method discontinuation at 12 months. The sample was stratified by each LARC method and adjusted hazard ratios were calculated from multivariable analysis including the following covariates: age, parity, race, income, history of sexually transmitted infection, socioeconomic, insurance, and marital statuses. Multivariable modeling results were similar when age was treated as a continuous variable (hazard ratio [HR] 1.00, 95% CI 0.99–1.02) compared with a categorical variable.
We found that nulliparous females, compared with parous females, were more likely to discontinue their LARC method among copper IUD and implant users (copper IUD: adjusted HR 1.76, 95% CI 1.13–2.73, implant: adjusted HR 1.89, 95% CI 1.35–2.64); however, this effect was not observed in levonorgestrel intrauterine system users, our largest LARC method subgroup (adjusted HR 1.16, 95% CI 0.92–1.46). Age younger than 20 years was not associated with early discontinuation (adjusted HR 0.95, 95% CI 0.74–1.22). Prior sexually transmitted infection, identifying as separated, divorced, or widowed, and being publically insured were associated with increased discontinuation.
Our study found that 12-month continuation rates for LARCs were high, greater than 82%, with similar rates for women of each age–parity status (range 82–86%). Extending our analysis to 24 months demonstrated continued high LARC use with rates varying from 66–76%. Nulliparity was associated with discontinuation in copper IUD and implant users; however, the high rates of continuation in these subgroups suggests that parity may not be a clinically important risk factor for discontinuation. More than three fourths of nulliparous females were still using their implant or copper IUD at 12 months. Our results add to the body of recent scientific literature showing high LARC continuation rates in adolescents3,14–17 and we provide additional evidence to dispel provider concerns about the use of LARC in nulliparous adolescents.
In 2011, Teal et al11 reported IUD continuation data in U.S. teenage mothers. In their cohort of 136 mothers aged 14–23 years, the continuation rate was 55% at 12 months. Comparatively, our parous adolescent and young women group aged 14–23 years had much higher IUD 12-month continuation rates of 84% (95% CI 81–86) and 81% (95% CI 72–88) for the levonorgestrel intrauterine system and copper IUD, respectively (Table 2). These variances could be attributable in part to differences in participant recruitment and sample sizes. Teal study participants were enrolled from an adolescent pregnancy–postpartum program, wherein expulsion and desire for pregnancy were common reasons for IUD discontinuation. In a demographically similar cohort of postpartum adolescents, much higher implant continuation rates of 86% were observed.10 They postulated the implant is a better choice for parous adolescents because a large proportion of IUD discontinuations were attributed to symptoms that would not be expected to occur with the implant. In contrast, we found excellent continuation rates for all three LARC methods and equally endorse their use in adolescents.
There is little consensus regarding the effect of nulliparity on LARC continuation, particularly in adolescents.15–19 Alton et al16 found higher rates of IUD discontinuation among nulliparous women. However, further analysis linked this to the young age of the patients rather than their nulliparous status. Contrary to this, we found that after controlling for age, nulliparous participants were more likely to discontinue their copper IUD or implant, but not the levonorgestrel intrauterine system. Although we hypothesized a disparity in continuation rates between young nulliparous females and older parous women, only small differences were found, and the overall effect of nulliparity was small. These findings provide evidence that nulliparous adolescents and young women are not a high-risk group for LARC discontinuation.
In a clinical setting that is committed to encouraging and facilitating LARC use, IUDs and implants were equally popular choices among adolescents and young women aged younger than 20 years (49% compared with 51%). In addition, adolescents and young women continued to use their LARC method, and continuation rates were similar to the general reproductive-aged population. These findings indicate that all LARC methods are acceptable to adolescents and young women, and this is an important consideration in our mission to reduce teenage pregnancy rates and dispel the common misperception that LARCs are unsuitable for teenagers and nulliparous women.
Strengths of our study include a large, diverse participant database that allowed us to effectively describe method continuation as well as other factors related to continuation. Participants were allowed to choose their preferred contraceptive method, which is more generalizable to clinical practice. Additional strengths of this study include the relatively long duration of follow-up compared with previous reports of 6- or 12-month continuation.
There are also several limitations to our study. There is potential for health care provider bias, because the superior contraceptive effectiveness of LARC was emphasized to our participants. However, a standard script was used for each patient, and information was provided about all reversible contraceptive methods. The Contraceptive CHOICE Project population was a convenience sample recruited from a single geographical area and may not be generalizable to other populations or the entire United States. Nonetheless, it does include a large, diverse group of young women at high risk of unintended pregnancy, including more than 800 participants aged 14–19 years.
We found high IUD and implant continuation rates in nulliparous adolescents. This is important information to allay health care provider concerns and reluctance to provide LARC methods to these women. Combined hormonal contraceptive methods are the most common reversible methods used in the U.S. However, the risk of unintended pregnancy is twice as high in adolescents and women younger than 21 years of age using these methods compared to older women.3 Thus, the expansion of LARC access among sexually active adolescents and young women, regardless of parity status, is imperative.
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