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Volume CXXXII, Number 22 |
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Five FAQs about B.C.
JEFF BENSON, M.D.
Do Birth Control Pills cause cancer? Epidemiologic studies have suggested that breast cancer is hormonally mediated, and the question of whether OCP's (Oral Contraceptive Pills) increase your risk of breast cancer has been answered with conflicting data. The most recent, and the strongest studies, have not shown any indication of increased risk, even in women with a family history of breast cancer.
There is little doubt about other gynecologic cancers. Because they suppress ovulation, and all of the cellular growth and stimulation associated with egg development, OCP's are actually protective against ovarian cancer. Similarly, because they greatly reduce hormonal stimulation of the endometrium (the lining of your uterus), OCP's also reduce risk for endometrial cancer. Finally, though for somewhat unclear reasons, OCP's have been recently shown to reduce risk for colo-rectal cancers.
Does long-term use of Birth Control Pills cause infertility? Actually, long-term use of OCP's may increase fertility. First, some of the more important non-contraceptive benefits of OCP's are reduced risk of endometriosis, pelvic inflammatory disease (PID), ovarian cysts and uterine fibroids, four conditions which together cause over 50 percent of infertility due to "female factors." Second, preventing pregnancies includes preventing tubal pregnancies, most of which cause irreparable damage to the affected fallopian tube or require its surgical removal. Finally, by suppressing ovulation, and thereby "preserving" eggs, OCP's may actually improve your chances of conceiving later on. British studies have shown, for instance, that 75 percent of women who had taken birth control pills for five years or more, conceived within six months of stopping their pills, compared to 70 percent of those who had never taken OCP's.
Do Birth Control Pills cause weight gain? Weight gain is often cited as an unfortunate and unavoidable side effect of OCP's. Until fairly recently, however, this assertion had not been scientifically evaluated. Now we have more information. One study from Penn State followed 66 women from adolescence through age 21. Roughly half took OCP's, and half didn't. The researchers found no significant differences in body weight, body shape, or percentage of body fat between the two groups. All of the women gained some weight, as part of the natural changes their bodies underwent as they aged.
Another study analyzed the daily weights of women during four cycles of OCP use, and found that almost all gained about a half-pound in the first two weeks of their cycle, but lost it again in the last days of the cycle. The researchers wondered whether this cyclic weight fluctuation played a part in the perception that OCP's cause weight gain.
One of the newest OCP's, Yasmin, has been marketed as a birth control pill that not only doesn't cause weight gain, but might even cause weight loss. The progestin component of Yasmin, drospirenone, has mild diuretic effects, and so lessens the fluid retention some women experience on other OCP's. Several studies have documented small initial weight losses on Yasmin (about a pound), but all of them also demonstrated eventual return to baseline weight after extended use.
Do OCP'S have to be started on a Sunday? Although many OCP's are packaged that way, there is in fact only one reason for a "Sunday-start." If you start your pills on a Sunday, you'll get your period on Monday or Tuesday of the fourth week. Drug manufacturers make the assumption that you're less likely to want to have sex during your period, and more likely to want to have sex on a weekend rather than a weekday!
Is it safe to go more than a month without a period? Many women have modified their OCP schedules to postpone bleeding for vacations or weddings. Many clinicians now recommend "continuous cycling." You take three weeks of a pill pack, and then start right in to the next pill pack, without pausing for a week of "sugar pills" and a pill period. Studies have shown that it's not just safe to cycle continuously, and have only three or four periods per year -- it's actually healthier.
If you think back historically, it's only very recently that women have not been pregnant or lactating, and hence not ovulating, through most months of their reproductive years. Remember that frequent ovulation, and all of the hormonal stimulation and cycles associated with it, are very definitely linked to higher cancer risks, whereas not ovulating, whether from pregnancy, lactation, or birth control pills, has proven protective effects.
Continuous cycling of OCP's also increases their contraceptive efficacy (presumably by suppressing your own hormonal cycle four out of four weeks, not just three).
It also turns out that there never was a compelling physiologic reason for OCP's to have a four-week cycle in the first place. John Rock, the Catholic obstetrician who pioneered the first contraceptive pill, hoped that his creation would seem sufficiently "natural" that it would somehow slip under the Vatican's radar. Rock knew that, on his Pill, "a cycle of any desired length could presumably be produced," and he very consciously engineered a 28-day cycle, promoting it as a natural variant of the approved rhythm method.
More questions about OCP's? Come on in to the Health Center! They're one of our favorite topics!
Jeff Benson, M.D.
Dudley Coe Health Center
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