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A New Form of Birth Control
What it is...
Depo-Provera is the injectable form of the synthetic hormone, depo- medroxyprogesterone (DMPA), that serves as a contraceptive. DMPA is similar to the hormone progesterone which is produced in the ovaries to help control the menstrual cycle (http://www.plannedparenthood.org/BIRTH-CONTROL/depoforyou.htm#what the shot is). Approved by the FDA in October of 1992, Depo-Provera is manufactured by Pharmacia and Upjohn Co. (http://www.centerwatch.com/patient/drugs/dru649.html). Women receive the injection of 150mg in their upper arms or buttocks every three months (http://www.pangea.ca/whc/depoapp.htm).
How it works...
Depo-Provera works by employing a few mechanisms to prevent or delay pregnancy. First, it stops ovulation, the process in which one of many unripe eggs found in the ovaries becomes ripe and enters the uterus to be fertilized, by prohibiting the ovaries to release an egg. It does so by blocking hormone signals called gonadotropins which are sent out by the hypothalamus and pituitary gland and are essential for ovulation. Ovulation usually takes place halfway between the starting points of two menstruation cycles. The injection is most effective when received five days after the start of the menstruation cycle because then it can stop ovulation before it can even start. This claim is clearly supported by a control study in which women in group 1 were given the injection on the 7th day of their menstrual cycle, while women in group 2 were given the injection on their 5th day. Development of follicles and continued ovarian activity were the factors that determined the effectiveness of the injection administration in each group. These factors were monitored by progesterone levels and vaginal ultrasounds. Essentially, the results of this study found that the women in group 1 (who received the injection on the 7th day) displayed both follicular growth and ovulation. Thus the scientists concluded that the injection is most useful when administered on the 5th day and no later because it can then put a stop to ovulation (Petta, Hays, Brache, Massai, Hua, Alvarez-Sanchez, Croxatto, d'Arcangues, Cook, Bahamondes, 2001).
Second, by thickening the excretions made by the vagina, it makes it difficult for sperm to fertilize an egg because they can not pass through as easily as they would be able to under natural circumstances. Thus it decreases sperm penetration (http://www.pangea.ca/whc/depoapp.htm).
Third, Depo-Provera reduces the density of the endometrium, the lining around the uterus, which causes a fertilized egg to die because it can not attach to a thin lining (http://www.centerwatch.com/patient/drugs/dru649.html). However, the thinning of this vaginal layer may allow the area to be more susceptible to infection, as one study proposed. This study monitored a group of women before and after receiving DMPA in terms of vaginal signs through vaginal biopsies. The results found that the thickness of the epithelial layer surrounding the uterus decreased by an average of about 11% in the 38 participants (Miller, Patton, Meier, Thwin, Hooton, Eschenbach, 2000).
Although it uses ovulation prevention as its main weapon, Depo-Provera also affects the onset of pregnancy by thickening the vaginal excretions and thinning the endometrium. These three mechanisms for birth control are supported by studies whose results are compiled in the National Library of Medicine database.
This injectable contraceptive is considered to be 99.7% effective in preventing pregnancy for at least up to one year. This figure can be compared to the birth control pill which is only 95% effective. The manufacturer of the product supports the claim of Depo-Provera’s effectiveness for obvious commercial reasons (to enhance the success of the product economically) and perhaps for the validity of the claims (http://www.depoprovera.com/about/effectiveness.htm).
Due to the international market which this
drug has created, there have been various studies conducted across nations.
One such study, at the Zhejiang Academy of Medical
Sciences in China, followed every 3 months for 1 year 1985 Depo-Provera users,
of whom only 3 (less than .2%) became pregnant, a result that testifies to its
high rate of effectiveness (Shao, Jiang, Fu, 1999).
The main reason for its effectiveness is the hindering of ovulation for an average of three months. The absence of ovulation makes it impossible for a woman to become pregnant. Many times, after it stops ovulation, it also creates an irregular menstrual cycle. In a majority of cases, women that take the injection completely stop having their periods. This happens because Depo-Provera causes the ovaries to stop sending out eggs. Once the period stops, the eggs can not be released, and therefore there can be no egg to be fertilized. After the initial injection, periods usually assume a normal cycle after about twelve months (http://www.depoprovera.com/about/side_fx.htm).
The American Academy of Family Physicians (AAFP) does not conclude that the injection is 99.7% effective, but it does proclaim that it is far more effective than the pill or other contraceptives (http://familydoctor.org/handouts/043.html). A study (described in more detail under “Disadvantages...”) found that even though most Depo-Provera users experienced changes in menstrual cycles and weight, this injectable contraceptive is very effective for women who are at a “high risk for rapid repeat pregnancy” (Hellerstedt and Story, 1996, page 450).
Just as with any prescription drug, there are certain restrictions for using this contraceptive. It is not to be used on women who are pregnant, have irregular bleeding, liver disease, breast cancer, or who are allergic to any of the ingredients in Depo-Provera. Women with other conditions, such as depression, heart disease, diabetes, hypertension, and migraines, put themselves at risk of worsening their conditions if they use this contraceptive (http://www.pplm.org/dp.html). A prospective study compared the depressive symptoms of 189 Depo-Provera users to those of 274 non-users, with all participants ranging in age from 18-39. The results of the study found that Depo-Provera users were 40% more likely than non-users to exhibit depressive symptoms. Interestingly, the findings also showed that users who discontinued use were 60% more like than non-users to exhibit depressive symptoms. Possible reasons given for these symptoms include a physiological effect the drug has and social factors of the user (i.e. stressful lifestyle which might have caused users to turn to this form in the first place due to its reliability and long-lasting effects) (Civic, Scholes, Ichikawa, LaCroix, Yoshida, Ott, Barlow, 2000). These precautions are provided by the manufacturer’s web site and several other sites as well.
Depo-Provera has a number of advantages. It only has to be injected once every three months, as opposed to once a day or prior to sexual intercourse. It delays pregnancy for a full three months as opposed to a week or a month. It is very convenient for a woman who has a tendency of forgetting to take her oral contraceptives and is also beneficial to one who may not want her partner or family members to know that she is using birth control for whatever reason(s) (http://www.pangea.ca/whc/depoapp.htm). Additionally, DMPA does not contain any estrogen, decreases the prevalence of cramps, and protects against endometrial cancer. A woman can use it six weeks after giving birth to a child, so that she can delay or prevent any future pregnancies. (http://www.plannedparenthood.org/BIRTH-CONTROL/depoforyou.htm#Advantages to the shot).
Many of these advantages are obvious from the product descriptions, but others are common to several web sites of organizations that have an interest in selling the product as well as those that feel obliged to inform the public.
While it has a few unique advantages, Depo-Provera also has many disadvantages that should be considered before using. Because the shot has to be administered four times a year, it is not as advantageous as receiving no shot, which could only result from abstinence. But because that (the practice of abstinence) is improbable and impractical in today’s society, four trips to the doctor is not a considerable disadvantage. However, this injection does not allow a woman to become pregnant for up to eighteen months if she chooses to stop taking the injection and wishes to become pregnant. Also, the injection does not in any way protect against sexually transmitted diseases. A Depo-Provera user therefore should ideally use a condom or another form of protection from such diseases (http://www.pplm.org/dp.html).
The injection not only has physiological shortcomings but also psychological ones. For instance, women receiving the injection have an excuse to be less aware of their sexual behavior than women on a contraceptive that requires more responsibility, such as the pill (http://www.pangea.ca/whc/depoapp.htm).
This contraceptive has many adverse side effects that are not usually associated with the more common contraceptives (http://www.plannedparenthood.org/BIRTH-CONTROL/depoforyou.htm#Disadvantages to the shot). The less harmful of these include nausea, headache, fatigue, dizziness, nervousness, and abdominal pain.
Two of the most common side effects from this injection are irregular menstrual cycles (many times no menstrual cycle at all) and an increase in appetite which results in weight gain (http://www.depo-users.com/interview.htm). According to the Journal of Adolescent Health, a study followed 35 people who had discontinued use of Depo-Provera to determine reasons for their discontinuation and their experiences after the. The participants were female adolescents with an average age of 16.5 who were checked up on every three months and were given physical examinations during follow-up sessions throughout a period of 12 months. The results of the study showed the dominance of complaints about irregular bleeding (defined as bleeding flow for more than seven days and/or an interval between periods of either less than 21 days or more than 35 days) and weight gain (according to increase in Body Mass Index) (Harel, Biro, Kollar, Rauh, 1996). Another study found in the same journal used 22 adolescent mothers to determine possible factors that could lead to discontinued use of Depo-Provera, as well as other contraceptives. Nineteen of the participants used the injection and showed irregularities in menstrual patterns and weight gain. Even though the focus of this study was to determine factors that led to participants’ views about various contraceptives, the findings are nonetheless informative about Depo-Provera and its side effects (Hellerstedt and Story, 1998).
Last but not least, two of the most harmful side effects are loss of bone density as the product of a decrease in calcium, which puts users at risk for osteoporosis, and a higher risk of breast cancer (http://www.pangea.ca/whc/depoapp.htm). Bone density loss among Depo-Provera users is supported by a study mentioned in Drug Safety, which came to the conclusion that the drug is most harmful in terms of bone density when administered for a period of more than five years and to those who are younger than 16 years of age (Comer, 1999). In contrast, many studies have been done to determine the relationship, if any, between DMPA use and breast cancer. However, most have come to the same conclusion that scientific evidence does not point to a dose-response relationship, or any other kind for that matter, between DMPA use and breast cancer risk.
While the manufacturer’s web site lists a few of these side effects, it does not go into detail about each one or how serious they can be. A site produced by the AAFP, as well as other sites showcasing findings from the AMA and JAMA, explain in depth most of these side effects and caution potential users because they, unlike the manufacturer, have a job to inform the consumer about a potentially-dangerous product, regardless of the effect that information might have on the commercial success of that product.
After meeting with failure and enduring many clinical trials, Depo-Provera was finally approved last year in the United States after it already had seen much success across the world. Due to its recent introduction into the market, it has not been possible to conduct extensive studies on the long-term effects of this product in women in the U.S. However, because Depo-Provera is spread internationally, studies on effectiveness have been conducted in other parts of the world. In Saudi Arabia, a retrospective study looked at women with an average age of 31 who had taken Depo-Provera as a contraceptive. Of the 165 women, 85% displayed a degree of differences in menstrual patterns, ranging from spotting to amenorrhea (period cessation). Only 4% chose to switch contraception methods. The findings from this study support the basic side effects that have been found to occur in women in the U.S. Additionally, the fact that only 4% of the participants chose to switch methods is a testament to the effectiveness of the drug and overall satisfaction which it provides. Even though they experienced these side effects, the majority of the women were pleased with its work, as are many current Depo-Provera users (Sobande, Al-Bar, Archibong, Sadek, 2000). The results from this study and others done across the globe can be used to draw conclusions on the effect that this injection might have on women in the United States since the physiological composition of humans is generally the same regardless of ethnicity. (http://www.pangea.ca/whc/depoapp.htm).
Although the manufacturing company claims the product to be 99.7% effective, other sources conclude that the injection is highly effective but that it also has the potential to cause very harmful long-term effects, which have not been related to other contraceptives. These other sources include organizations that have no commercial interest in the product (i.e. AMA, FDA); instead, they have a duty to warn potential consumers of possible harms and side effects of the product. Many of them present accurate information to the public because of their concern for the well being of society.
A number of studies have been performed to explain the mechanisms whereby Depo-Provera prevents pregnancy. The basic conclusion of these studies rests on the scientific basis that the hormone depomedroxyprogesterone, a gonadotropin inhibitor, prevents ovulation, and thus pregnancy. A number of studies have also shown how effective this product is by analyzing its effects on various types of subjects. The general conclusion from these studies is that among other side effects, irregular bleeding and weight gain are the most popular effects of Depo-Provera. The conclusions from these studies also indicate that this drug is highly effective in terms of doing what it is meant to do, especially when compared to other forms of contraceptives. But as we all know, the only 100% effective contraceptive is abstinence.
Civic, D., Scholes, D., Ichikawa, L., LaCroix, A., Yoshida, C., Ott, S.,
Barlow, W. (2000).
Depressive symptoms in users and non-users of depot
medroxyprogesterone acetate. Contraception, 61, 385-390.
Harel, Z., Biro, F., Kollar, L., Rauh, J. (1996). Adolescents' reasons for and experience after discontinuation of the long-acting contraceptives Depo-Provera and Norplant. Journal of Adolescent Health, 19, 118-123.
Miller, L., Patton, D., Meier, A., Thwin, S., Hooton, T., Eschenbach, D. (2000). Depomedroxyprogesterone-induced hypoestrogenism and changes in vaginal flora and epithelium. Obstetrics and Gynecology, 96, 431-439.
Petta, C., Hays, M., Brache, V., Massai, R., Hua, Y., Alvarez-Sanchez, F., Croxatto, H., d'Arcangues, C., Cook, L., Bahamondes, L. (2001). Delayed first injection of the once-a-month injectable contraceptive containing 25 mg of medroxyprogesterone acetate and 5 mg of E(2)-cypionate: effects on ovarian function. Fertil Steril, 75, 744-748.
Sobande, A., Al-Bar, H., Archibong, E., Sadek, A. (2000).
Efficacy and acceptability of depomedroxyprogesterone
acetate injection - As a method of contraception in
Saudi Medical Journal, 21, 348-351.
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