Contraception, With Statistical Analysis Contraception is the name for those medical strategies employed to prevent a woman from becoming pregnant after sexual intercourse. It can be broken down according to the strategy employed: these strategies are loosely called Barrier methods, Intrauterine devices, Hormonal methods, Surgical methods (also known more commonly as "sterilization") and finally Behavioral methods. I will give a quick survey of what these different strategies entail, noting the most common or popular methods within each category, as enumerated in Trussell's (1998) statistical survey of contraception. I will then discuss these individual methods in a little more detail, noting not merely the medical "safety" (measured in terms of risks or contraindications, and also measured according to the statistical analysis by Trussell which I have reproduced at the end of this work as Figure 1.)

Barrier methods are the simplest mechanical means of preventing a sperm cell from fertilizing an egg cell during coitus, the process which leads to the fertilized egg implanting itself on uterus, the rich loamy surface of the female womb where it can be nourished and grow into a fetus. Barrier methods prevent the fertilization of female egg by male sperm by presenting a barrier that separates sperm from egg, blocking the two from meeting and thereby blocking fertilization. The best-known barrier method is probably the latex condom: but other technologies including the cervical cap and the diaphragm also qualify as barrier methods, because they work in the same basic way that a condom works: by providing a technologically-designed barrier to conception.

Intrauterine devices are similarly technological to Barrier methods, however they operate by a slightly different means: they are implanted into the woman's cervix, and interfere with the ability of the fertilized egg to land itself on the rich loamy surface of the uterus and receive nourishment. The fertilized egg having failed to find a place to land -- due to interference caused by the implanted device -- it eventually passes out through the cervix and is therby expelled from the body without pregnancy occurring (despite fertilization having occurred).

Hormonal methods follow initial research done in the 1950s and 1960s by Dr. Carl Djerassi, a Stanford University medical researcher who faced such opposition on "moral" grounds for his research into reproductive technology (traditionally an area on which religion has strong moral teachings) and was forced to do much of his research and development in Mexico, where morally-inspired research regulations were more lax. Djerassi had noted the existence of special hormones which were only released by the female endocrine system in response to conception, designed to prevent further conception: he theorized that a certain cocktail of those hormones would persuade a woman's body that it was already pregnant, and developed the first contraceptive pill, based on manipulation of the female hormonal and endocrine system's own natural method of preventing conception. The first generation of pharmaceuticals had astonishingly high levels of hormonal content compared with today's pharmaceuticals, though -- it turned out that the body's ability to detect such hormones is far more sensitive than was originally theorized, and apparently a little bit administered pharmaceutically goes a long way. Also, over the past 50 years, new methods have been developed for administering the same hormonal cocktail but not doing so orally -- so other hormonal methods include injections and implants which differ in their system of delivery but which operate in the same way that Djerassi had originally theorized, by using natural hormonal methods of blocking conception to do the work of family planning.

Surgical contraceptive methods are slightly more drastic, because they imply sterilization of the patient. The two most common methods of surgical contraception are tubal ligation -- in which a woman's Fallopian tubes are "tied off" by a surgeon, to prevent further eggs from being released during ovulation -- and vasectomy -- in which a man's testicular vas deferens is severed or "tied off" surgically, thereby preventing active sperm from being released during ejaculation. (Other forms of total sterilization -- such as hysterectomy or orchiectomy, i.e., total castration -- are more radical procedures normally only performed in response to life-threatening illness, not simply to provide a method of contraception.) Tubal ligation and vasectomy are also noteworthy for being potentially reversible, surgically -- in other words, though the protection they aim to afford from unwanted pregnancy is almost total, there is at least a chance in most cases that the procedure can ultimately be reversed if pregnancy becomes a desirable state.

Finally, Behavioral methods are the last category, and these emphasize contraception by means of things like Abstinence -- which is not technically a form of contraception...

The "Rhythm Method" is famously mainly because it received the endorsement of the Vatican -- one of the world's most fierce opponents to the idea and the practice of contraception and family planning -- so as the one form of approved contraception available to the world's Catholic population, the "Rhythm Method" has a historically-enshrined status and surprisingly, Ecochard and Pinguet (1998) discovered rates of failure as low as 1% for the rhythm method, but this is due to a more strict regimen of watching the body's natural clues to ovulation than most women seeking contraceptive methods would be capable of adhering to. But otherwise this is a means of avoiding fertilization without actually employing any form of technological or chemical contraception. Indeed the whole point of the rhythm method seems to be that it avoids chemicals or barriers, but just seeks to avoid the likelihood of impregnation. The World Health Organization's "Family Planning: A Global Handbook for Providers" (2007) represents the current state of thinking on all methods of contraception, and includes Withdrawal (but not Abstinence).
It is at this point that I must introduce Trussell's data for the effectiveness of these contraceptive methods, which I reproduce here as Figure 1. Before looking at the data, it is important to note how Trussell defines his terms: he ranks each method by the percentage of pregnancies which occur in one year of "typical" use (which may include mistakes in use made by the patient, such as forgetting to take a pill one morning) versus "perfect" use:

FIGURE 1. STATISTICAL ANALYSIS TABLE OF CONTRACEPTIVE METHOD FAILURE, MEASURED BY PERCENTAGE OF WOMEN EXPERIENCING UNINTENDED PREGNANCY IN THE FIRST YEAR OF USE, ACCORDING TO "TYPICAL" AND "PERFECT" USE.

Source: Trussell, J. "Contraceptive efficacy." In Hatcher R.A., Trussell J., Nelson A.L, Cates W., Stewart F.H., Kowal D. Contraceptive Technology: Nineteenth Revised Edition. New York: Ardent Media, 2007.

% of women experiencing unintended pregnancy in first year, after

METHOD TYPICAL USE PERFECT USE

None 85

Withdrawal 27 4

"Rhythm Method" (Ovulation) 25 3

Diaphragm (with spermicide) 16 6

Condom, Female (no spermicide) 21 5

Condom, Male (no spermicide) 15 2

Pill 8 .3

Patch 8 .3

NuvaRing 8 .3

Depo-Provera 3 .3

Copper IUD .8 .6

Mirena IUD .2 .2

Implanon .05 .05

Tubal Ligation .5 .5

Vasectomy .15 .10

As we can see from Trussell's statistics, hormonally-based methods seem to be incredibly effective. -- although there are occasionally contraindications for patients who become ill from the additional hormonal interference caused by the medication. Hilgers and Stanford (1998) go a bit further in their analysis of the failure rates of the hormonal contraceptives: if used strictly as directed, the failure rates fall to less than 1%. In the following year, Howard and Stanford (1999) followed this up with an additional analysis which again suggests that the flaws lie in patient education rather than the reproductive technology itself. It is the inability of the user to adhere to the strictness of the rules which accounts for Trussell's (1998) statistics suggesting higher failure rates for these hormonally-based technologies: used correctly, the failure rate for the birth control pill (e.g.) is astonishingly low.

But the most telling statistic is that of 85% likelihood within a year of an unplanned pregnancy with no method employed at all. For most people withdrawal and the rhythm method have a one in four chance of pregnancy, these being the closest methods which do not employ medical technology. The World Health Organization's "Family Planning: A Global Handbook for Providers" (2007) represents the current state of thinking on all methods of contraception, and includes Withdrawal (but not Abstinence). Skouby (2004) in a survey of five European countries, recommends that health care professionals do not even suggest the withdrawal method as the failure rates are too high.

But the APA (2005) issued a statement saying that all research indicates that sex eductation which is not abstinence-based is more effective at stopping HIV. DiCenso and Guyatt (2002) indicated that abstinence-based education seems to increase the rate of pregnancy, largely by keeping sexually-active young adults ignorant of the medical facts of sexual intercourse. Santelli and Ott (2006) laid out the position paper of the Society for Adolescent Medicine, which rules heavily against abstinence-based sex…