Clinical Review

• New routes, new regimens • Array of options for emergency contraception clip-and-save chart • The IUD makes a comeback

OBG Manag. 2004 August;16(8):45-53

References

1. Sulak PJ, Kuehl TJ, Ortiz M, Shull BL. Acceptance of altering the standard 21-day/7-day oral contraceptive regimen to delay menses and reduce hormone withdrawal symptoms. Am J Obstet Gynecol. 2002;186:1142-1149.

2. Anderson FD, Hait H. A multicenter, randomized study of an extended cycle oral contraceptive. Contraception. 2003;68:89-96.

3. Timmer CJ, Mulders TM. Pharmacokinetics of etonogestrel and ethinyl estradiol released from a combined contraceptive vaginal ring. Clin Pharmacokinetics. 2000;39:233-242.

4. Sullivan H, Furniss H, Spona J, Elstein M. Effect of 21 day and 24 day oral contraceptive regimens containing gestodene (60 μg) and ethinyl estradiol (15 μg) on ovarian activity. Fertil Steril. 1999;72:115-120.

5. Croxatto HB, Urbancsek J, Massai R, Coelingh BH, van Beek A. A multicentre efficacy and safety study of the single contraceptive implant Implanon. Implanon Study Group. Hum Reprod. 1999;14:976-981.

6. 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.

7. Jain J, Dutton C, Nicosia A, Wajszczuk C, Dode FR, Mishell DR. Pharmacokinetics, ovulation suppression and return to ovulation following a lower dose subcutaneous formulation of Depo-Provera. Contraception. 2004;70:11-18.

8. Trussell J, Ellertson C, Stewart F, Raymond EG, Shochet T. The role of emergency contraception. Am J Obstet Gynecol. 2004;190:S30-S38.

9. Andersson K, Odlind V, Rybo G. Levonorgestrel-releasing and copper-releasing (Nova T) IUDs during five years of use: a randomized comparative trial. Contraception. 1994;49:56-72.

10. Peterson HB, Xia Z, Hughes JM, Wilcox LS, Tylor LR, Trussell J. The risk of pregnancy after tubal sterilization: findings from the U.S. Collaborative Review of Sterilization [see comment]. Am J Obstet Gynecol. 1996;174:1161-1168.

11. Andersson K, Batar I, Rybo G. Return to fertility after removal of a levonorgestrelreleasing intrauterine device and Nova-T. Contraception. 1992;46:575-584.

12. World Health Organization. Improving Access to Quality Care in Family Planning: Medical Eligibility Criteria for Contraceptive Use. Geneva: WHO; 2000.

13. Milsom I, Andersson K, Andersch B, Rybo G. A comparison of flurbiprofen, tranexamic acid, and a levonorgestrel-releasing intrauterine contraceptive device in the treatment of idiopathic menorrhagia. Am J Obstet Gynecol. 1991;164:879-883.

14. Crosignani PG, Vercellini P, Mosconi P, Oldani S, Cortesi I, De Giorgi O. Levonorgestrel-releasing intrauterine device versus hysteroscopic endometrial resection in the treatment of dysfunctional uterine bleeding. Obstet Gynecol. 1997;90:257-263.

15. Lahteenmaki P, Haukkamaa M, Puolakka J, et al. Open randomised study of use of levonorgestrel releasing intrauterine system as alternative to hysterectomy [see comment]. BMJ. 1998;316:1122-1126.

16. Ness RB, Grisso JA, Vergona R, et al. Oral contraceptives, other methods of contraception, and risk reduction for ovarian cancer [see comment]. Epidemiology. 2001;12:307-312.

17. Zieman M, Guillebaud J, Weisberg E, Shangold GA, Fisher AC, Creasy GW. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril. 2002;77:S13-S18.

18. Holt VL, Cushing-Haugen KL, Daling JR. Body weight and risk of oral contraceptive failure. Obstet Gynecol. 2002;99:820-827.

Plan B Consists of 0.75 mg levonorgestrel taken within 72 hours of intercourse, followed by a second dose 12 hours later. This regimen has fewer side effects than the Yuzpe plan and may be slightly more effective. Unfortunately, the US Food and Drug Administration failed to approve over-the-counter status for this drug, so a prescription is still necessary.

IUDs. Insertion of a copper IUD (Paraguard)—but not a levonorgestrel-containing device (Mirena)—within 72 hours after intercourse is almost completely effective in preventing pregnancy. It also provides continuing contraception. Its mechanism of action is preventing implantation of a fertilized egg. Mirena has no efficacy in this regard.

“Every Woman, Every Visit,” the American College of Obstetricians and Gynecologists’ public education campaign, urges Ob/Gyns to provide advance prescriptions for emergency contraception at every office visit.

The IUD makes a comeback

After many years of declining choices in the realm of intrauterine devices (IUDs), the Mirena levonorgestrel-containing system was released in the US market in 2000. Like the Paraguard copper IUD, the Mirena prevents pregnancy at a rate equivalent to tubal ligation. These devices last for 5 and 10 years, respectively.^9,10

In the United States, interest in IUDs declined after they were associated with salpingitis and tubo-ovarian abscess. More recent epidemiological evidence indicates that IUDs do not increase the risk of infection over the general population, but the rate is higher than with other forms of contraception, which offer some protection against salpingitis. Antibiotic prophylaxis is not necessary.

The removal rate for pelvic inflammatory disease is much lower for Mirena than for the copper IUD and may be related to the low levels of levonorgestrel, which thicken cervical mucus and prevent sperm transport.⁹

Ectopic pregnancy rates with the Mirena are about 1/8 to 1/10 those observed in the general population. Once the Mirena device is removed, fertility returns rapidly^9-11

Recommended for the chronically ill. According to the World Health Organization, IUDs are the safest form of contraception for medically complicated patients.¹² Certainly, they are underutilized in this circumstance.

Noncontraceptive benefits. Slow release of low doses of levonorgestrel by Mirena reduces endometrial thickness and menstrual blood loss.¹³ In fact, several studies have found the Mirena to be equivalent to endometrial ablation.¹⁴ In a randomized study, two thirds of the women scheduled for hysterectomy for abnormal uterine bleeding cancelled surgery due to satisfaction with Mirena’s bleeding profile.¹⁵

Ovarian cancer also is reduced.¹⁶

Does obesity limit contraceptive efficacy?

Decreased efficacy of the contraceptive patch, observed in overweight women,¹⁷ especially those heavier than 198 lb, prompted reevaluation of other forms. In a retrospective analysis, Holt and colleagues¹⁸ found a higher pregnancy rate in women heavier than 155 lb as the estrogen dose decreased. In contrast, no pregnancies occurred in women weighing more than 198 lb in a randomized trial² of 30 μg ethinyl estradiol/150 μg levonorgestrel (Seasonale). It is unclear why Holt failed to analyze progestin content, since it is the progestin that inhibits ovulation and prevents pregnancy.

Unfortunately, few clinical trials involve obese women. For example, the contraceptive ring was not evaluated in obese women.

Despite this shortcoming, I have not changed my prescribing of contraceptives in obese women, but await better, more convincing data. Until then, it seems wise to include a broad range of body weights in future trials.

The author serves on the Speakers Bureau for Barr, Berlex, and Wyeth-Ayerst.