Volume CXXXIII, Number 19 March 29, 2002 f

Emergency contraception
JEFF BENSON, M.D.

Dear Dr. Jeff: I've heard a lot of discussion recently about "Emergency Contraception". Is that the "Morning After Pill"? Is it available at the Health Center? S.G.

Dear S.G.: A variety of forms of "Emergency Contraception" ("EC") are currently available. Dedicated "Morning-After Pills" contain some combination of progesterone and estrogen. "Preven" contains both estrogen (ethinyl estradiol) and progesterone (levonorgestrel), the hormones found in most oral contraceptive pills. In Preven, they are formulated in considerably higher doses. Multiple doses of birth control pills (often "Ovral"), can also be taken in a similar manner with the same effects. "Plan B" contains only the progestin, levonorgestrel. It is more effective than Preven and Ovral, and has far fewer side effects. Plan B is the formulation we prescribe at the Health Center.

The exact mechanism of action of these hormonal preparations is complex. Human and animal studies have shown effects at several stages of the reproductive cycle: ovulation, fertilization, egg transport and hormonal support, and implantation. If the timing is right, like regular birth control pills, EC will suppress ovulation and cause changes in cervical mucus that make it impenetrable to sperm. It will also impede transport of a fertilized egg through the fallopian tubes to the uterus, as well as implantation of the egg in the endometrial lining of the uterus. None of these medications will harm an implanted embryo.

All forms of emergency contraception should be taken as soon as possible after unprotected intercourse. A second dose needs to be taken 12 hours after the initial dose.

If 100 women have completely unprotected intercourse during the second or third week of their cycles, studies have shown that eight will likely conceive. Preven and Ovral are about 75 percent effective, and will reduce this number to two women. Plan B is 89 percent effective, and so reduces this number to one.

The sooner EC is taken, the more effective it is. While this was always intuitively clear, recent studies have demonstrated that every 12-hour delay in starting the medication may decrease its effectiveness by as much as 50 percent.

Three million unintended pregnancies occur each year in this country. Half of all American women will have at least one unintended pregnancy. The majority of these women use a regular method of contraception, none of which, unfortunately, is 100 percent effective. Accidents happen: condoms break, diaphragms slip, birth control pills are sometimes forgotten.

Sometimes sex is unplanned - or unwanted. Very sadly, each year, thousands of American women are the victims of rape. Emergency contraception can at least help eliminate one associated trauma - the prospect of an unwanted pregnancy.

At the Health Center, we consider emergency contraception a safe, effective, back-up birth control method. By delaying or inhibiting ovulation or fertilization, or preventing transport or implantation of a fertilized egg in the uterus, EC prevents pregnancy. Emergency contraception does not interrupt a pregnancy. It will not work if a woman is already pregnant, and it will not harm a developing fetus.

Emergency contraceptive pills are available in the U.S. only by prescription. There has been much discussion about how to improve women's ease, speed and cost of access to EC. In three states now (California, Washington and Hawaii), women are able to obtain emergency contraception directly from pharmacists without having to visit a clinic or health care provider first.

Plan B has been available at the Health Center for some time. This year, we have been able to add it to our formulary, and dispense it to students free of charge. We would like all women to have some Plan B on hand, in their medicine cabinets, immediately available, "just in case". The sooner after unprotected intercourse Plan B is started, the more effective it is. Please come in to the Health Center to pick some up, and to learn more about how to use it safely and effectively.

Jeff Benson, M.D.
Dudley Coe Health Center