This analysis adds support to prior studies suggesting that women using highly effective birth control methods other than OCs may be less likely to seek the added protection of condoms.
16–19 Thus, in conjunction with prior research, our analysis suggests that advocating the use of contraceptive methods that have low typical-use failure rates requires simultaneous emphasis on the importance and benefits of combining these methods with condoms. By using a nationally representative sample and controlling for demographic variables, we move beyond prior analyses in identifying populations for which this message might be particularly important. Indeed, depending on the measure implemented to assess contraceptive use patterns, our analysis suggests that among NH-black women and women without a high school diploma, condom use may be especially low for those relying on user-independent methods as compared with OCs.
Our findings also illustrate that numerous women are placing themselves at risk for STIs and unplanned pregnancies that could be avoided. Although condom use odds by partner status were highest for women with multiple partners, the proportion of these women at risk for STIs who used a condom in conjunction with their highly effective method was quite low (16.5% to 36.2%). In addition, based on current contraceptive use patterns, we estimated that each year, approximately 982,000 U.S. women using a highly effective method can expect an unplanned pregnancy. Nearly 190,000 of these women may choose to have an abortion. If anywhere from half to all of the women using highly effective methods alone also used condoms, unplanned pregnancies and abortions among these women potentially could be reduced by about 40% to 80%.
The large reduction in unplanned pregnancies and abortions also provides a rationale that may be much easier for women to use than STI avoidance when negotiating condom use. Women having difficulty negotiating condom use within relationships that may not be mutually monogamous should therefore be counseled to emphasize the contraceptive benefits of dual-method use, while also taking advantage of the benefits of STI protection. Additionally, women in mutually monogamous relationships who are switching to OCs or injectibles should be counseled that they can maximize protection against unplanned pregnancy by continuing their use of condoms.
Despite the benefits of combining condoms with a second method, this is not the optimal solution for all women. Very few women (0.5%) can expect to become pregnant during a 12-month period using IUDs or implants. This percentage is even lower than for the combined use of condoms with OCs or injectibles (1.3% to 1.7%). Thus, for women in a mutually monogamous relationship, the use of an IUD or implant alone may be preferable. On the other hand, women who perceive substantial barriers to actively planning their pregnancies may wish to use condoms alone. Women who perceive such barriers often choose less-effective methods, and may report that a pregnancy resulting from contraceptive failure was in fact intended, or at least welcomed.
31 Nonetheless, in other cases, the use of less effective methods is not a means to avoid active planning. For instance, compared with mainstream Protestant women, Catholic women are more likely to use coital avoidance methods,
32 but they also have comparatively high abortion rates.
33 Given the numerous documented advantages of planned pregnancies, we must improve our understanding of the processes women use to make family planning decisions and when the selection of a less effective method might be most appropriate.
While using condoms for dual protection may not be optimal for all women, promoting this practice among women for whom it is appropriate has the potential to result in substantial cost savings. Adding condoms to a more highly effective method does require additional spending for a second method. However, in contrast with implants and IUDs, which often are not provided because of high upfront costs, male condoms, OCs, and injectibles are comparatively inexpensive and are provided by virtually all publicly funded family planning clinics.
34,35 Thus, combining condoms with OCs and injectibles has the potential to prevent many unplanned pregnancies while imposing small additional costs. Given estimates that every dollar invested in helping women avoid unwanted pregnancies saves $4.02 in Medicaid expenditures that otherwise would have been needed for pregnancy-related care,
34 a simple intervention such as this could result in enormous cost savings.
Given the potential benefits of dual-method use with condoms, more research is needed to better understand how we can most effectively promote the use of condoms with a second, more highly effective contraceptive method. Promoting dual-method use will require that we overcome unique barriers, including: the desire to not worry about contraception at each act of intercourse that may motivate women to switch to another method; inconsistent condom use or abandonment of condoms with the adoption of a second, more highly effective contraceptive method;
36 the need to simultaneously address two unrelated decision processes for women with committed and casual partners;
36–38 and the negative association of condoms as a method for preventing STIs that acknowledges the potential for infidelity and distrust within a relationship.
7–9 One suggestion for promoting dual-method use has been to implement targeted interventions that assess individual perceptions of unplanned pregnancy and STI risks within the contexts in which women are making contraceptive decisions.
36,39 However, while this type of intervention has promoted faster self-reported initiation of dual-method use, it has yet to have an effect on unplanned pregnancy rates or the acquisition of STIs.
40 Interventions focusing on men also need to be explored, given that having a male partner with a positive attitude about condoms is one of the strongest predictors of dual-method use.
21,41Limitations
While our study illustrates the importance of advocating dual-method use with condoms and identifies groups in which the need for monitoring and intervention is greatest, our analysis had several limitations. Foremost, both of our outcome measures had certain weaknesses. One advantage of using the methods that women relied upon at their last intercourse is that the probability that a woman would have been classified as a condom user would have been proportional to the consistency of her condom use. Nonetheless, this measure reflects a single act of intercourse and indicates nothing about the diversity of contraceptive use patterns that women may have with different partners. In particular, women with multiple partners may be more likely to use condoms in secondary or casual relationships, but condom use in this context would have been missed for women who last had intercourse with their primary, committed partner. On the other hand, while enumerating the methods used during the interview month provides a more comprehensive measure of contraceptive choice, our analysis based on this measure provides no indication of the consistency of condom use. Moreover, because the information necessary to exclude women who had not had intercourse in the past month had been removed from the public use dataset, we had to rely on a recoded variable to exclude women who had not been sexually active for a full three months. Consequently, we misclassified a certain number of women as single-method users simply because they had not had the opportunity to use a condom in the past month.
In addition to the weaknesses of our outcome measures, the small number of women who relied on user-independent methods limited the conclusions we could draw from our analysis. The limited number of data points in some strata undoubtedly led to significant interaction terms and differences between our outcome measures that we might not have seen with a larger sample size. Moreover, even though there may be important differences in condom use patterns among women using IUDs/Norplant and injectibles, the small number of women using these methods forced us to combine them into a single category. In particular, although we classified injectibles as a user-independent method, this form of contraception differs from IUDs and implantable contraceptives in that women must still return to their health-care provider every three months for their injections. Consequently, women using injectibles must make a greater effort to ensure the effectiveness of their method, but they also have more frequent opportunities for counseling.
21A final limitation of our analysis was that we were unable to include women aged 15–19 years in our adjusted models. Given the prevalence of STIs among teenagers
42 and their high rate of unplanned pregnancy,
3 monitoring condom use in this group is important. However, given the declines in teenage pregnancy rates and increases in their condom use that were not paralleled in adult women during the decade leading up to the last NSFG,
12,13,43,44 detailed analyses focusing on this age group alone
13,14,43 likely are of greater value than a combined analysis.
This article has been 
