Clinical Review

UPDATE: CONTRACEPTION

OBG Manag. 2009 August;21(8):15-26

References

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2. Lei ZW, Wu SC, Garceau RJ, et al. Effect of pretreatment counseling on discontinuation rates in Chinese women given depo-medroxyprogesterone acetate for contraception. Contraception. 1996;53:357-361.

3. Rodriguez G, Faundes-Latham A, Atkinson LE. An approach to the analysis of menstrual patterns in the critical evaluation of contraceptives. Stud Fam Plann. 1976;7(2):42-51.

4. Belsey EM, Machin D, d’Arcangues C. The analysis of vaginal bleeding patterns induced by fertility regulating methods. World Health Organization Special Programme of Research, Development and Research Training in Human Reproduction. Contraception. 1986;34:253-260.

5. Hatcher RA, Trussell J, Nelson AL, Cates W, Jr, Stewart F, Kowal D. Contraceptive Technology. 19th ed. New York: Thomson Reuters; 2008.

6. Affandi B. An integrated analysis of vaginal bleeding patterns in clinical trials of Implanon. Contraception. 1998;58(6 Suppl):99S-107S.

7. Funk S, Miller MM, Mishell DR, Jr, et al. Implanon US Study Group. Safety and efficacy of Implanon, a single-rod implantable contraceptive containing etonogestrel. Contraception. 2005;71:319-326.

8. Zheng SR, Zheng HM, Qian SZ, Sang GW, Kaper RF. A randomized multicenter study comparing the efficacy and bleeding pattern of a single-rod (Implanon) and a six-capsule (Norplant) hormonal contraceptive implant. Contraception. 1999;60:1-8.

9. Croxatto HB. Clinical profile of Implanon: a single-rod etonogestrel contraceptive implant. Eur J Contracept Reprod Health Care. 2000;5 Suppl 2:21-28.

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11. Belsey EM. Vaginal bleeding patterns among women using one natural and eight hormonal methods of contraception. Contraception. 1988;38:181-206.

12. Haider S, Darney PD. Injectable contraception. Clin Obstet Gynecol. 2007;50:898-906.

13. Jain J, Jakimiuk AJ, Bode FR, Ross D, Kaunitz AM. Contraceptive efficacy and safety of DMPA-SC. Contraception. 2004;70:269-275.

14. Polaneczky M, Liblanc M. Long-term depot medroxyprogesterone acetate (Depo-Provera) use in inner-city adolescents. J Adolesc Health. 1998;23(2):81-88.

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19. Backman T, Huhtala S, Blom T, Luoto R, Rauramo I, Koskenvuo M. Length of use and symptoms associated with premature removal of the levonorgestrel intrauterine system: a nation-wide study of 17,360 users. BJOG. 2000;107:335-339.

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Intrauterine contraception

The main mechanism of contraceptive action in the levonorgestrel intrauterine system (LNG-IUS) (Mirena) is significant thickening of cervical mucus, resulting in a physical barrier to sperm penetration; ovulation inhibition may also contribute. In a study of women who had been using the LNG-IUS for 4 years, 88% (15/17 cycles) were still ovulatory according to progesterone levels, but only 47% (8/17 cycles) showed normal follicular growth and rupture by ultrasonography.¹⁸ The efficacy of the LNG-IUS is 99.8%.⁶

Advantages of the LNG-IUS include its high effectiveness; long-term action; increased rate of menstrual cycles that are shorter, lighter, and marked by less cramping as use continues; and a high likelihood of amenorrhea as duration of use lengthens.

As with other progestin-only contraceptives, the major disadvantage of the LNG-IUS is associated irregular bleeding that, as is the case with DMPA, appears to decrease with duration of use for most women.

What are the expected changes in bleeding patterns with LNG-IUS? Local effects of the LNG-IUS on the endometrial lining include stromal pseudodecidualization, glandular atrophy, and increased infiltration of leukocytes in the endometrium. These effects, combined with partial inhibition of ovulatory function, commonly result in irregular bleeding.

The number of days of bleeding-spotting is pronounced in the first 3 to 6 months after insertion. Approximately 18% of women reported bleeding-spotting in the first 3 months; 6% to 25%, at 6 months; and only 1% of women, approximately, at 12 months (TABLE 2).

In a survey of Finnish women who used the LNG-IUS, 45.2% reported irregular bleeding, and 18.1% reported spotting, at some point during use.¹⁹ Importantly, the prevalence of bleeding-spotting does decrease with duration of use. Nevertheless, as many as 10% of women still report irregular bleeding-spotting at 2 years (TABLE 2).

As with other progestin-only contraceptives, amenorrhea rates for the LNG-IUS vary (TABLE 4). In a Brazilian study of 256 women, 44% reported amenorrhea at 6 months; 50%, at 12 and 24 months.²⁰ In a larger study of 1,821 Finnish women, however, only 17% of women reported amenorrhea at 12 months.²¹ A survey study of approximately 16,000 Finnish women who used the LNG-IUS found that 75% reported that they “totally or occasionally missed menses” at any time during as long as 5 years of use.¹⁹

The discontinuation rate for the LNG-IUS is lower than for the ENG implant or DMPA. Still, changes in bleeding patterns are the most common reason for discontinuation. At 1 year of use, approximately 10% of women discontinue the LNG-IUS because of changes in the bleeding pattern (TABLE 5).

In the most comprehensive study of early removal of the LNG-IUS, the total discontinuation rate—for all reasons—increased to 13% at 2 years, 19% at 3 years, 25% at 4 years, and 35% at 5 years.¹⁹ Women who reported excessive bleeding were almost three times more likely to discontinue the LNG-IUS early than women who did not report such a problem (RR, 2.77; 95% CI: 2.5, 3.07). Women who experience spotting are almost twice as likely to discontinue early (RR, 1.89; 95% CI: 1.75, 2.05). Others have reported the cumulative discontinuation rate to be as low as 14.4% at 5 years (when measuring discontinuation because of changes in menstrual bleeding) and as high as 35% at 5 years (when considering the total discontinuation rate for all reasons).²¹

Amenorrhea lowers the discontinuation rate. In one analysis, women who reported that they “totally or occasionally missed periods” were half as likely to discontinue the LNG-IUS as those who didn’t make such a report (RR, 0.46; 95% CI: 0.43, 0.50).¹⁹

PERSPECTIVE AND GUIDANCE FOR YOUR PRACTICE

Irregular bleeding is common with the LNG-IUS in the first 3 to 6 months of use, but overall discontinuation is relatively low—probably because of the high likelihood that bleeding patterns improve over time. Still, irregular bleeding remains the most common reason for discontinuation. Realistic expectations about bleeding patterns and the lower likelihood for amenorrhea, in comparison with DMPA, are important variables to discuss with women who are considering the LNG-IUS.

Progestin-only pills

Progestin-only pills (POPs) have a failure rate that ranges from 1.1 to 9.6 for every 100 users in the first year.²² A POP is used most often by women in whom estrogen is contraindicated, including those who are breastfeeding.²³

Disadvantages. POPs require precise adherence and make irregular vaginal bleeding likely. Although 40% to 50% of women who take a POP have normal menstrual cycles, 40% have short, irregular cycles, and another 10% experience even more markedly irregular cycles—from spotting to amenorrhea.²²

Studies that precede the WHO Belsey system showed that 1) as many as 70% of women who use a POP reported “breakthrough bleeding-spotting” in one or more cycles and 2) 6% to 16% have “breakthrough bleeding or inter-menstrual spotting” in all cycles (TABLES 2 AND 3).^24,25