Health Related Behavior Study 2018 – General Sexual Health and Sexual Behavior of the Reservists

The Health Behavior and Behavior Survey (HRBS) is the US Department of Defense's (DoD) primary survey of the health, health behaviors and well-being of military personnel. The HRBS, which has been conducted regularly for more than 30 years, covers areas that may affect military readiness or the ability to meet the demands of military life.

The Department of Defense commissioned the RAND Corporation to review and implement the 2018 HRBS for active and reserve military personnel. This report examines the results for the Reserve. This summary examines sexual behavior and health outcomes.

Some results are also compared to the U.S. Department of Health and Human Services' Health Promotion 2020 (HP2020) goals for the U.S. population. Because the armed forces are significantly different from the population (for example, members of the armed forces are more likely to be young and male than the population), these comparisons are presented for comparative purposes only.

Risky Sexual Behaviors and Outcomes

Among all HRBS respondents, 15.9% (confidence interval [CI]: 14.9-16.8) reported having had more than one sexual partner in the past 12 months. In addition, 33.2% (confidence interval [CI]: 32.0-34.3) reported having sex with a new partner in the past 12 months without using a condom.

The HRBS defined military personnel at high risk for human immunodeficiency virus (HIV) infection as men who had had sex with one or more men in the past 12 months, military personnel who had engaged in vaginal or anal intercourse with more than one partner in the past 12 months, and military personnel who had had a sexually transmitted infection (STI) in the past 12 months. The study found that 17.7% (CI 16.7-18.7) were at high risk of HIV infection.

Of all respondents, 2.5 percent (CI 2.0-2.9) reported having caused or had an unintended pregnancy in the past year. Women (3.2%, CI 2.5-3.9) reported this more often than men (2.3%, CI 1.8-2.7). This difference is probably due to the lack of data on unintended pregnancies in men. The proportion of reservists reporting unintended pregnancy was lower than that of US women of childbearing age (4.5%, CI 4.1-4.9).

Use of Contraceptives

In 2016, the Department of Defense issued a memorandum (DHA-IPM 16-003) establishing comprehensive standards of care for contraceptive methods and counseling. These standards adopt the Centers for Disease Control and Prevention (CDC) recommendations as guidelines for military clinical practice.

This section examines military personnel's use of contraceptives in the past 12 months, their most recent vaginal birth, and the time they experienced or caused an unintended pregnancy. The most common methods used by HRBS respondents were condoms and contraceptive pills.

Long-acting contraceptives, such as intrauterine contraception, were associated with significantly lower rates of unintended pregnancy. Long-acting methods are more effective partly because they do not require the user to remember or use them correctly, as other methods do. The most commonly used long-acting method is the intrauterine device.

Table 1: Contraceptive method used during the last vaginal intercourse in the last 12 months

Contraceptive method Percentage used
Highly effective methods
  • Male sterilisation (vasectomy) 8.5 (CI: 8.0-8.9)
    IUD 9.6 (CI: 9.0-10.3)
  • Female sterilisation (e.g. tubal ligation, hysterectomy) 6.3 (CI 5.8-6.7).
  • Implanted contraception (e.g. Implanon) 3.4 (CI 2.9-3.8).

Other methods
  • Condom 23.6 (CI 22.5-24.6)
  • Contraceptive pills 17.8 (CI 16.9-18.8)
  • Contraceptive injections, patch, ring or diaphragm 4.7 (CI 4.1-5.2).
  • Other method 4.8 (CI 4.3-5.3)

No contraceptive method or not applicable
  • No contraceptive method used 19.1 (CI 18.2-20.0)
  • No vaginal contraception in the past 12 months 15.0 (CI 14.1-15.9).
  • I/ my partner tried to get pregnant 6.1 (CI 5.6-6.6)
  • I/ my partner was already pregnant 2.9 (CI 2.5-3.3)

The HP2020 target is that 91.6% of women aged 15-44 at risk of unintended pregnancy would use contraception (or whose partners used contraception) at last sexual intercourse. The latest available civilian population estimate, based on 2015-2017 National Household Survey data, is 79.6% (CI: 76.7-82.2).

The HRBS survey found that among serving women aged 17-44 years who were at risk of unintended pregnancy, 73.8 percent (CI: 71.4-76.1) used contraception during their last vaginal intercourse (CI: 71.4-76.1).

The HP2020 initiative aims to achieve 69.3% of women aged 20-44 years using a more effective or reasonably effective method of contraception (sterilisation or the use of a contraceptive implant, IUD, contraceptive pill, injection, patch, ring or film).

Data from the National Household Survey show that between 2015 and 2017, 60.2% (CI: 57.4-63.0) of all US women aged 20-44 who were not already pregnant and were not trying to conceive used an effective or moderately effective method of contraception. The HRBS study found that 60.3% (CI 58.1-62.6) of women aged 20-44 years used such a method during their last vaginal intercourse in the past 12 months.

Unintended pregnancies related to deployment, contraceptive availability and contraceptive counselling

Unintended pregnancies during deployment cause problems and functional difficulties for servicewomen that can jeopardize soldiers' ability to function and troop readiness. The 2016 National Defense Authorization Act required that military women receive comprehensive counseling on all contraceptive methods prior to deployment and at deployment health screenings.

The 2017 National Defense Authorization Act mandated data on service members' experiences with access to family planning services and counseling. The Defense Department requires contraceptive counseling to be provided at the annual physical exam and at pre-deployment and deployment medical visits.

The HRBS showed that 0.02% (CI: 0.00-0.05) of service members had had an unintended pregnancy during deployment in the past year. Overall, 33.4% (CI: 29.3-37.5) of women and 15.2% (CI: 13.1-17.3) of men reported having received contraceptive counselling before deployment.

Before deployment, 82.3% (CI: 77.1-87.6) of women and 12.2% (CI: 7.2-17.1) of men reported being able to obtain or substitute their preferred method of contraception. At coverage, 73.7% (CI: 66.5 to 80.9%) of women and 14.0% (CI: 8.2 to 19.8%) of men reported being able to obtain or substitute their preferred method of contraception.

HIV Tests

The CDC recommends that people at risk be tested for HIV annually, and recommends that men who have sex with men consider testing every three to six months. The Department of Defense requires HIV testing at least every two years. To be eligible for deployment, a service member must have received an HIV test result within the past 24 months.

According to the HRBS, 71.4% (CI: 70.2-72.5) of service members reported having been tested for HIV in the past 12 months and 38.5% (CI: 37.3-39.6) reported having been tested in the past six months. Among those at high risk of HIV infection, 79.1 percent (CI 76.3-81.9) had been tested in the past 12 months.

Among men who reported having sex with men, 84.2% (CI 77.8-90.6) reported being tested for HIV in the past 12 months and 67.3% (CI 59.4-75.3) reported being tested in the past six months. The HP2020 target is for at least 68.4% of men who have sex with men to be tested for HIV annually.

Differences to the active component

To compare the HRBS results for active and reservists, RAND researchers developed regression models that took into account the demographic characteristics of respondents. Significant differences between reservists and active duty members included the following.

  • Less likely to have multiple sexual partners, had sex with a new partner in the past year without a condom, had a sexually transmitted disease, and were at high risk of HIV infection.
  • Less likely to have used a highly effective method of contraception during their most recent vaginal intercourse.
    less likely to have been tested for HIV in the last 12 months.

Conclusions and Impact on Policy

A significant proportion of military personnel engage in a range of sexual risk behaviours, including intercourse with multiple partners and, most importantly, intercourse with a new partner without a condom. The Ministry of Defence, the Armed Forces and the Coast Guard should ensure that conscripts have easy and free or reduced access to condoms wherever they are and consider regular STI testing.

The Ministry of Defence, Navy and Coast Guard should consider extending contraceptive counselling to men. According to the National Family Planning Survey, 60% of men could benefit from planning services, with the greatest need among men aged 20-29, but only 10% of them receive contraceptive counseling [2].2] These strategies include counseling men on condom use and how to help their partners use other methods.

The Department of Defense, the services and the Coast Guard should work to increase the consistent and effective use of contraception. New contraceptive guidelines adopted by the MoD state that the use of IUDs and implants should be considered as the primary method of contraception.

However, more training and education on the benefits of more effective contraceptive methods may be needed for providers and service personnel, as these methods may not be suitable for all women. The Department of Defense, the Services, and the Coast Guard could increase annual HIV screening of at-risk individuals by improving screening as part of the annual personal health examination.

Although the current personal health check form asks relevant questions, it is not clear whether information on different risk factors is combined to identify those in the highest risk category, or whether more frequent (annual or biennial) HIV screening should be routinely conducted for certain risks (e.g. men who have sex with men) or combinations of risks.


RAND conducted the 2018 HRBS survey among active duty and reserve military personnel in the U.S. from October 2018 to March 2019. Five reserve components – Air Force, Army, Navy, Marine Corps, and Coast Guard – and two National Guard components – Air National Guard and Army National Guard – participated in the Reserve Component Survey.

The 2018 HRBS was a confidential online survey that allowed researchers to target reminders to non-respondents and reduce survey burden by linking responses to administrative data. The sample was selected using a random sampling method stratified by grade level, grade and gender. The overall weighted response rate to the survey was 9.4%, so the final analytical sample consisted of 16,475 responses for the reserve.

To address missing data, RAND researchers used imputation, a statistical procedure that uses available data to estimate missing values. To represent the reserve population, responses were weighted to avoid underrepresenting service members in certain strata. Point estimates and 95% CIs are presented in this survey report.

RAND researchers tested whether there were differences in each outcome at key factor levels or subgroups – service area, salary level, gender, race/ethnicity, and age group – using a two-step procedure based on the Rao-Scott chi-square test for overall differences in factor levels, and if the overall test was statistically significant, a two-sample t-test examining all possible pairwise comparisons between factor levels (e.g. men vs. women).

Readers interested in these differences should consult the full final report of the HRBS 2018 Reserve Component. This summary is one of eight in the Reserve Component; this summary and six of the other seven summaries correspond to different chapters in the full report, with the eighth summary providing an overview of all findings and policy implications. A similar series of eight reports analyses the results of the active component.


The response rate to the survey is considered low. While low response rates do not automatically mean that the survey data are biased, they do increase the possibility of bias. As with any self-report survey, social desirability bias is possible, especially for sensitive questions and topics. For some groups, representing a small percentage of the total military population, survey estimates may be inaccurate and should be interpreted with caution.

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