Past Pill Use:
Were earlier versions of the Pill safe?
There have been two major trends in Pill pharmacology: a reduction in the estrogen dose and a change in the progesterone formulation. The earliest oral contraceptives contained 150 micrograms of estrogen, which produced intolerable side effects. The dose was sequentially decreased to 100, 50, and now less than 50 micrograms, making it easier for women to stay on the medication. With the decrease in estrogen dose the risks of heart attack and stroke have apparently become smaller. Recent studies have shown that the lowest-dose Pills, when given to low-risk women, have little or no increased risk of stroke and heart attack. The risk of serious clotting events has likely decreased as well. Importantly, physicians have increased the Pill's safety during this time by screening women at higher risk for serious side effects and by assisting Pill users with smoking cessation.
The newest, or "third generation" Pills contain newer types of progesterone that are also intended to decrease side effects. These progesterones have fewer testosterone-like side effects, and appear to have a better effect on cholesterol levels, acne and abnormal hair growth. From a safety perspective, there was concern in the 1980s that these pills had a higher risk of clotting events. This finding remains somewhat controversial, and the benefits of these pills still appear to outweigh the drawbacks, especially in low-risk women. On the other hand, these pills appear to have a smaller risk of heart attack than other, more testosterone-like formulas.
If a woman took the Pill in the 1960s, could it still have effects on her health?
The cancer benefits of the Pill, specifically the reduced risk of endometrial and ovarian cancer, may persist for 15 or more years after stopping the medication. Therefore, women who started the Pill in the 1960s and continued on it may still experience these health benefits.
In terms of health risks, it appears that adverse risks of taking the Pill will begin to decrease when a woman stops using the medication. Once a woman has been off of the Pill for ten years, her risk equals that of a woman who has never used the Pill. A European group has studied oral contraceptive users and non-users from 1968 until the 1990s, and found that this risk reduction applies to even the earliest users of the Pill.
Why did doctors dispense the early, high-dose Pill without informing women of its risks? How do researchers determine doses today?
Though the consequences of Pill use are potentially dangerous, serious effects have always been rare. Thus the contraceptive had to be given to tens of thousands of women before doctors could detect these outcomes and conduct studies to confirm them. Prior to this it was not known that hormonal contraception would cause these effects. Subsequent efforts have focused on lowering the dose of medication enough to avoid side effects while preserving the Pill's ability to prevent pregnancy. Furthermore, as the doses have been dropped lower and lower, such side effects as breakthrough bleeding have increased. While this is a relatively minor effect, it may be intolerable to some Pill users, thus making the medication unusable.
If a woman with past Pill use takes hormone replacements, is she at greater risk for cancer?
The Women's Health Initiative, a recent large study of hormone replacement therapy, confirmed an increase in breast cancer risk for women taking a specific form of this treatment. We do not yet know whether this risk was greater, less, or equivalent in women who had previously used birth control pills.
Some earlier studies suggested that women with a strong family history for breast cancer and women on early, high doses of the Pill had a small increase in their breast cancer risk. However, a recent large study of birth control pills and breast cancer showed that this risk in Pill users is the same as that of non-users. This study looked at more women on the lower Pill doses. They did not look for an interaction between Pill use and hormone replacement therapy.
Do synthetic hormones and natural hormones have different long-term effects?
All of the current FDA-approved hormone formulations are synthetic, with the exception of Premarin, which is used in some hormone replacement therapies. Unfortunately, the "natural hormones" found in some herbal and soy-based preparations have never been studied for their long-term effects. We do not know much about how these herbal and plant hormones act on the body. Long-term studies will need to be done before we can draw any conclusions about their health effects.
What is the current thinking on hormone replacement therapy?
As with oral contraceptives, hormone replacement therapy appears to increase the risk of a few serious conditions, such as heart disease, stroke, clotting events and breast cancer. As with the Pill, the absolute increased risk for these events is small. On the other hand it also has health benefits, including decreases in hot flashes, vaginal dryness, osteoporosis, and colon cancer. Every woman must weigh her own potential risks and benefits of using hormones and individualize her treatment.
Visit the U.S. National Library of Medicine and National Institute of Health's MEDLINE Plus Web site for more information on pregnancy, contraception, hormone replacement therapy, and other women's health topics.