National Partnership for Women & Families

Monthly Women's Health Research Review

Study assesses LARC initiative, continuation in military health care system

Summary of "Initiation and continuation of long-acting reversible contraception in the United States military healthcare system," Chiles et al., American Journal of Obstetrics & Gynecology, March 14, 2016.

"The extent to which members of the U.S. military, military retirees, and their family members initiate and continue [long-acting reversible contraception (LARC)] is largely unknown," according to Daniel Chiles of the San Antonio Military Medical Center's Department of Pediatrics and colleagues.

The researchers noted that about "350,000 women of reproductive age currently serve in the U.S. military's active duty or selected reserve force, and one million others have a parent or spouse currently serving in one of these capacities." The researchers wrote that while "[t]hese women have access to universal healthcare, including no-cost contraception with unlimited method switching, ... over 7 unintended pregnancies a year occur for every 100 active duty service women, and over half of all pregnancies among active duty service women are unintended." According to the researchers, "These unintended pregnancies have a physical and emotional impact on both the mother and infant, and degrade military readiness." Citing the "high efficacy and reliability" of LARC methods, the researchers wrote, "Efforts to increase LARC initiation may improve health outcomes for this population, and mitigate the profound consequences on readiness and cost to the military."

In this study, the researchers aimed to "determine initiation and long-term continuation rates of LARC in a large, diverse population with universal health care" and "understand LARC usage patterns in the United States military healthcare system."


For the study, the researchers examined "a retrospective cohort of over 1.7 million women, ages 14-40 years, enrolled in the military healthcare insurance program, TRICARE Prime, between October 1, 2009 and Sept 30, 2014." According to the researchers, "TRICARE Prime covers medical care provided at military treatment facilities or contracted through civilian providers for all active duty service members, military retirees under the age of 65, and members of the national guard and reserve who have been called up to active duty." The program also insures the family members of covered individuals, "including spouses and dependent children under the age of 26," the researchers wrote.

The researchers "used the Military Health System Management Analysis and Reporting Tool (M2) to review medical and pharmacy billing records of enrolled women during the study time period." According to the researchers, "The primary outcome of interest was time from insertion to discontinuation of individual LARC methods," which included the copper IUD (Cu-IUD), the 52-mg levonorgestrel IUD (LNG-IUS) and the implant.

The researchers followed participants until they "reach[ed] one of three end points: method discontinuation, disenrollment from TRICARE Prime, or the end of the study period." According to the researchers, "Continuation rates were calculated over the first 36 months for all methods and over the first 60 months for intrauterine contraceptives [IUD], and were further characterized by examination of demographic characteristics at the time of insertion including: age, military duty status, type of clinic where method was inserted, and method type." The researchers noted that the "36-month and 60-month analyses represents the Federal Drug Administration's approved duration of use for the implant and the 52-mg LNG-IUS, respectively," and "allow[ed] for comparisons to previously established benchmarks for method continuation."


Overall, the sample included "188,533 initiators of LARC, including 140,553 who initiated intrauterine contraceptives and 47,980 who initiated a subdermal implant," the researchers wrote. They followed study participants "for an average of 14.7 … months after LARC insertion before achieving one of the study end points." The researchers noted, "At the time of LARC initiation, the average age of women in our sample was 25.9 … years, 75.8% were family members, and 31.8% had the insertion at a civilian network clini[c]."

According to the study, 74.6 percent of women initiating LARC opted for an IUD. Among women presenting for IUD insertion at military clinics, 56.1 percent opted for the LNG-IUS and 6.5 percent selected the Cu-IUD. The researchers noted that they "were generally unable to categorize the intrauterine contraceptive type among individuals receiving insertions in network clinics." The researchers found that 25.4 percent of women selected the implant.

Overall, the researchers found that:

  • Women opting for IUDs "were significantly older than implant users (26.9 years old … versus 23.0)";
  • "Family members of military service members were more likely than servicewomen on active duty to select intrauterine contraceptives"; and
  • "[W]omen seen for LARC placement in civilian network clinics were more likely than those seen in military clinics to select intrauterine contraceptives."

According to the researchers, the IUD insertion rate "remained relatively stable during the study interval with a range of 41.7-50.1 insertions/1,000 enrolled women per year. However, the implant insertion rate "increased from 6.1 insertions/1,000 women per year in 2010 to 23.0 insertions/1,000 women per year in 2014."

The researchers found that continuation rates for implants "were 76.8% at 12 months, 58.6% at 24 months, 45.8% at 33 months, and 32.0% at 36 months." In comparison, IUD "continuation rates were 83.5% at 12 months, 70.6% at 24 months, 61.2% at 36 months, 54.1% at 48 months, and 48.8% at 60 months." The researchers noted that IUD continuation rates "did not differ by device type." Overall, "the implant was more likely than intrauterine contraceptives to be discontinued prior to 36 months," according to the researchers.

In a separate analysis, the researchers found that "adolescents had the highest implant continuation rates over the first 36 months ... whereas 35-40 year old women had the highest intrauterine contraceptive continuation rates of any age group." The researchers in another analysis found that "the likelihood of early LARC discontinuation was highest among women who were 20-24 years old at the time of insertion, were seen in a military clinic rather than a network clinic for method insertion, and selected an implant for contraception rather than an intrauterine contraceptive."


The researchers found that LARC initiation in the military health system "is low but increasing," with continuation rates similar to those found in other studies and an overall increase in LARC use that is "consistent with national trends." According to the researchers, "Approximately half of women who selected the implant continued their method at least until 3 months prior to the recommended expiration date, and almost half of all women who selected intrauterine contraception continued their method until 60 months."

They wrote that while the study is consistent with research showing "LARC is typically continued by over 80 percent of users at 12 months," it also found that 13.8 percent of implant users -- including 16.9 percent of teenage users -- discontinued the method at 33-36 months. Roughly "half of implant users continued the method" at 33 months. "Perhaps the 33-month continuation rate of the implant is a better criterion for judging method continuation, because removals after 33 months likely indicate receipt of recommended care prior to method expiration," the researchers explained, citing data showing that "the implant and LNG-IUS may be effective for one year post recommended removal date."

The researchers also found that while prior research "found lower continuation among adolescents than among adults as a group," their study found that teenage users "had lower continuation rates than women in their late thirties, but higher continuation rates than women in their twenties at 36 months and women in their early twenties at 60 months." Further, according to the researchers, the study findings "suggest that adolescents have the highest implant continuation rates of any age group, approaching those of intrauterine contraceptives." The researchers wrote, "These higher continuation rates, compared to women in their twenties who represent the majority of LARC users, suggests that concerns about method continuation among adolescents should not be a barrier to LARC use in this age group." Furthermore, the higher continuation rates "support national recommendations for clinicians to recommend the most effective methods (i.e. LARC) before recommending less effective methods during contraceptive counseling to women of all ages."

The data "showing both increase in initiation and high continuation of LARC have military implications," the researchers wrote. According to the researchers, the findings show that "LARC may have the same potential to reduce rates of unintended or mistimed pregnancies and to increase cost-savings, as it has in the general U.S. population." This is particularly significant "for the military population, which tends to be young and at risk for pregnancy," the researchers explained, noting that unintended pregnancy rates are thought to be higher among military members than the general population. Moreover, according to the researchers, "LARC may reduce healthcare disparities, as rates of unintended pregnancy are higher among young women, minorities, and those with lower income," which is particularly significant given that "approximately one-third of active duty service members self-identify as members of minority groups."

In addition, the researchers noted that the "downstream effects of LARC could include an improvement in military readiness, as pregnancies among active duty service members and their family members directly affect operational readiness." The researchers point to studies showing that 10 percent of "women surveyed approximately one year into deployment ... reported having been unintentionally pregnant during that year" and 11 percent of servicewomen "were unable to complete a 15-month combat deployment due to a pregnancy." Moreover, the researchers noted that women in the military "report less frequent use of contraception during deployment than at home, despite benefits on contraception and menstrual regulation." In addition, according to the researchers, deployed servicewomen "also report difficulty with initiating and continuing contraception because of logistical and institutional barriers to obtaining reproductive health services in a deployed environment." The researchers wrote, "Use of highly effective, long-term contraceptive options that can be started before deployment and continued without need for medical support during deployment could make a valuable contribution to the health and welfare of these women."

The researchers concluded, "Overall, the high rate of LARC continuation found in this analysis supports LARC as first-line recommendations for women of all ages seeking contraception, including service members and their families, adolescents, and those with lower socioeconomic status."