 Fig.
1. Contraceptive failure during first year of use. (Data from Burnhill
MSA: Contraceptive use: the U.S. perspective. Int J Gynecol Obstet
62 (Suppl 1):S17–S23, 1998; and Hatcher RA, Trussell J, Stewart F et al:
Contraceptive Technology. 17th rev. ed. New York: Ardent Media, 1998. |
As shown in Fig. 1,
contraceptive methods with high first-year failure rates during typical
use are periodic abstinence, withdrawal, male condoms, diaphragms, and
spermicides.11, 12
Highly effective methods with low first-year failure rates during
typical use include copper or progesterone-bearing IUDs, OCs, implants,
injectables, and sterilization.
The
results of a recent 60-week, US multicenter, controlled, nonrandomized,
parallel study in which 1103 women used either a monthly contraceptive
injection containing MPA and estradiol cypionate (E2)
(Lunelle, n = 782) or an OC-containing triphasic norethindrone (NET)
and ethinyl estradiol (Ortho-Novum 7/7/7, n = 321) demonstrate the high
effectiveness that can be achieved with reversible contraceptives.13
In this trial, one unintended pregnancy was reported at the third visit
in a patient receiving the OC and no pregnancies occurred during 13
cycles of 28 days in study subjects receiving monthly injections.
Pregnancy rate estimates using Pearl index and life-table methods were
0.0 and 0.0, respectively, with the monthly injection and 0.3 and 0.4,
respectively, with the OC. Thus, both the monthly injections and the OC
provided a high degree of contraceptive efficacy. Because this was a
clinical trial, participants were highly motivated (and monitored).
Accordingly, higher failure rates are observed in routine clinical
practice. Increased use of these and other highly effective methods of
contraception by US women would decrease rates of unintended pregnancy
and induced abortion.
Effective methods of contraception are also highly cost-effective (Fig. 2).14
In an analysis in the managed care payment model, 5-year costs
associated with reversible methods increase as the effectiveness of the
method decreases; nearly all cost with less effective methods is
related to unintended pregnancy rather than method acquisition.14
With the highest cost-effective reversible methods—copper-T IUD,
implants, and injectables—method acquisition accounts for most of the
cost. Costs of barrier methods are increased by unintended pregnancy.
Among permanent methods of contraception, female sterilization is less
cost effective than vasectomy as the result of the greater cost of
tubal sterilization, including operating room and anesthesia
requirements.
 Fig.
2. The 5-year costs associated with contraceptive methods in the
managed care payment model. (Adapted from Trussell J, Leveque JA,
Koenig JD et al: The economic value of contraception: A comparison of
15 methods. Am J Public Health 85:494–503, 1995.) |
Characteristics of highly effective, reversible contraceptive methods are compared in Table 2.
Several comments are warranted with regard to differences in benefits
and risks associated with these methods. In terms of major risks, OCs
are known to have procoagulant effects related to the estrogen
component. Such procoagulant changes increase users' risk of deep vein
thrombosis. Although procoagulant effects were most pronounced with
high estrogen-dose OC formulations, mild procoagulant effects within
the normal range have been reported with formulations containing 35 μg
or less of estrogen.15
Unlike OCs, DMPA does not increase globulin production in the liver and
is not associated with increases in procoagulant factors.16 No procoagulant changes are seen with either levonorgestrel implants or the copper IUD.16
Table 2. Comparison of highly effective, reversible contraceptive methods
| Parameter | OC | DMPA | Implants | Copper Ultrauterine Device |
| Efficacy | User dependent | High | High | High |
| Length of protection | Continuous if taken daily | 3 months | 5 years | 10 years |
| Rapid return of fertility | Yes | No | Yes | Yes |
| Regular cycles | Yes | No | Variable | Yes |
| Amenorrhea | Uncommon | Common | Variable | No |
| Appropriate in nursing mothers | Suboptimal | Yes | Yes | Yes |
| Procoagulant | Yes | No | No | No |
| Noncontraceptive benefits | Established | Established | Unknown | No |
| Provider required to initiate | Yes (Rx) | Yes | Yes | Yes |
| Provider required to discontinue | No | No | Yes | Yes |
| Privacy | Requires pill pack | Yes | Seen or felt by some users | Usually (string may be felt by partner) |
OC, oral contraceptives; DMPA, depot medroxyprogesterone acetate.
(Adapted from Kaunitz AM: Injectable contraception: New and existing options. Obstet Gynecol Clin North Am 27:741–780, 2000.)
Another
concern with hormonal methods of contraception is their impact on bone
mineral density (BMD). Several studies of OCs, DMPA, and levonorgestrel
implants have examined changes in BMD. A history of OC use was found to
be protective against low BMD in a US cross-sectional study.17
In a large Swedish case-control study, OC use by women age 40 and older
was associated with a 25% reduction in postmenopausal hip fracture risk.18
Studies have found the OC use has a protective effect against
osteopenia in young, reproductive-age women with hypoestrogenic
conditions (e.g. hypothalamic amenorrhea or anorexia nervosa),
and helps maintain BMD in older reproductive-age women with declining
ovarian function.19 Available data suggest that use of levonorgestrel implants may have a neutral or beneficial effect on BMD.20
The impact of current or past use of DMPA on BMD has been addressed by 13 studies.16
Overall, current use of DMPA appears to be associated with a decrease
in BMD that is reversible following cessation of use and therefore
unlikely to have clinical importance. A New Zealand study found that
postmenopausal bone mineral density in former DMPA users was not
significantly different from that of never-users at any site.21
In this regard, the impact of DMPA on bone density resembles that of
lactation in that both lower ovarian production of estradiol, leading
to reversible declines in BMD.16
In
contrast to implants and the copper IUD, both OCs and DMPA have many
well-established noncontraceptive benefits. Both OCs and DMPA prevent
iron-deficiency anemia, ectopic pregnancy, pelvic inflammatory disease,
and endometrial cancer.22, 23
Additional noncontraceptive benefits of OCs include protection from
dysmenorrhea and menorrhagia, ovarian cysts, benign breast disease, and
ovarian cancers, emerging benefits such as the treatment of acne and
dysfunctional uterine bleeding, and the prevention of osteopenia and
osteoporotic fractures.18, 22, 24 An additional noncontraceptive benefit of DMPA is a reduced need for hysterectomy in women with uterine leiomyomata.23
Protection
against STDs represents a critical issue for reproductive-age women.
Because the trend toward initiating sexual activity at a younger age
and postponing marriage until an older age places women at increased
risk for both unintended pregnancy and STDs, clinicians should try to
encourage use of contraceptive options that achieve both goals.
However, as shown in Table 3,
the most effective reversible contraceptive methods (DMPA, implants,
IUDs, and OCs) do not protect users against STDs, whereas a method with
relatively low contraceptive efficacy—the male condom—provides the
greatest STD protection.25
Table 3. Protection against sexually transmitted diseases (STDs) with different contraceptive methods
| Contraceptive Method | Effects on Bacterial STDs | Effects on Viral STDs |
| Diaphragm, cervical cap, sponge | Some protection against cervical infection; increases organisms associated with bacterial vaginosis | No protection against vaginal infection or external genitalia transmission; prevention of HPV controversial |
| Female condom | In vivo protection against recurrent trichomonal infection suggests possible protection against other STDs | In vitro impermeability to cytomegalovirus, HIV |
| IUD | No protection | No protection |
| Latex male condom | Protection against most pathogens in genital fluids | Less protection against organisms such as HSV and HPV transmitted from external genitalia |
| Combination oral contraceptive | No protection against bacterial STDs | Data on HIV transmission risks conflicting; role regarding risk of HPV infection and cervical dysplasia unclear |
| DMPA implants | Assume no protection | May promote HIV transmission |
| Spermicide with nonoxynol-9 | Modest protection against cervical gonorrhea and chlamydia | Data conflicting on HIV transmission risks |
| Tubal ligation | No protection | No protection |
HPV, human papillomavirus; HIV, human immune deficiency virus; IUD, intrauterine device. HSV, herpes simplex virus; DMPA, depot medroxyprogesterone acetate.
(Adapted from Cates W Jr, Sulak PJ: Contraceptives and STDs: Alternative approaches to providing dual protection. Dialog Contracept 6:1–4, 9, 2000.)
Providing
the dual benefits of protection against pregnancy and STDs is a
particularly vexing challenge among adolescents. Clinicians have noted
that long-acting hormonal preparations such as DMPA or levonorgestrel
represent better options than OCs for pregnancy prevention in this
age-group because they remove need for daily compliance.26
However, a recent study in urban teens found that those using
levonorgestrel were less likely to report condom use at last sexual
contact or consistent condom use at follow-up 1 or 2 years later than
users of OCs or condoms.27
These findings suggest that both the sexual behavior and motivation to
use condoms in teens who use implants differ from those of teens who
use OCs and condoms. In addition, teens often fail to use OCs or
condoms in a fashion sufficiently consistent to prevent either
unintended pregnancy or STDs.
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