Plan B birth control pills have their limits
DEAR DOCTOR: My granddaughter’s college offers “morning-after” pills via vending machine. Using these pills without a doctor’s prescription and oversight can’t possibly be safe, can it?
DEAR READER: Between 2006 and 2010, one out of every nine women of reproductive age used some form of emergency contraception — often when other forms of contraceptives had failed. Although the subject raises both religious and ethical questions for some people, the reality is that so many women have already been safely treated with emergency contraception by doctors that some forms of the drugs are now available over-the-counter.
Oral emergency contraception works by delaying a woman’s ovulation, thus lowering the likelihood that sperm will fertilize an egg. Pregnancy rates among 20-something couples is 30 percent if intercourse occurs one to two days before ovulation. If intercourse occurs at any random point in a woman’s cycle, the overall chances of getting pregnant are only 4 to 6 percent. Studies of Plan B (levonorgestrel), the medication provided via
vending machines at some campuses, show an overall chance of pregnancy of 2.6 percent among women who’ve taken the drug.
If a woman is obese or overweight, the drug is even less effective. Plan B has other limitations as well. For maximum effectiveness, it must be used within 72 hours after intercourse, and it doesn’t work as well among women taking some seizure medications or St. John’s wort.
However, Plan B’s biggest downside is that it just doesn’t work very well. Plan B may give a false sense of security that a pregnancy won’t occur, so women should understand that they have other choices for emergency contraception.
The prescribed medication ulipristal acetate (Ella) has an efficacy rate of about 66.7 percent and can delay ovulation by five days.
The most effective form of emergency contraception is the insertion of a copper intrauterine device (IUD) by a doctor. This is 95 percent effective at preventing pregnancy.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.