CONTRACEPTION (STRATEGIESFOR BIRTH CONTROL)
There are many methods of contraception available, each with its own advantages and disadvantages. When selecting a contraceptive, the convenience, as well as the failure rate (chances of becoming preg-nant), have to be taken into account.
If a more permanent type of contraception is desired, sterilization can be performed. This is a surgicalprocedure in which the continuity of the reproduc-tive passage of sperm and ova is disrupted, prevent-ing fertilization. In males, the vas deferens on each side is cut, tied, and blocked as it ascends close to the scrotum as part of the spermatic cord before it enters the abdominal cavity. This procedure, known as va-sectomy, is simple and can be performed in minutesin a physician’s office. In females, the fallopian tubes are blocked by a procedure known as tubal ligation. This involves opening the abdominopelvic cavity, lo-cating the tubes, and producing discontinuity of the passage. This procedure is more complicated than vasectomy. The failure rate for these two procedures ranges from 0.02% to 0.45%.
Other contraceptive methods can be used on a less permanent basis. Oral contraceptives are pills that contain varying quantities of the hormones proges-terone and/or estrogen. The hormones are adjusted to prevent ovulation. The pills are taken 5 days after the start of menstruation and continued for 3 weeks. Fol-lowing this, the pills taken are placebos or contain small quantities of hormones. Thus, despite the pre-vention of ovulation, regular menstrual cycles are achieved. More than 20 brands of oral contraceptives are available, each with a different dosage of estrogen and progesterone. The brand most suitable for each individual has to be determined by a physician. Re-cently, skin implants, containing progesterone and progesterone injections, are available that provide birth control for a more prolonged period. The fail-ure rate for oral contraceptives ranges from 0.32% to 1.2%.
Intrauterine devices (IUDs) are in the form of asmall, plastic/copper loop, T or 7 (shapes) that can be inserted into the uterine cavity. The exact mechanism of action is still uncertain, but it is believed that the uterine secretions/atmosphere is altered to prevent the implantation of the fertilized ovum. Not com-monly used in the United States, it is a popular form of contraception in other countries. The failure rate ranges from 5% to 6%.
Some methods work as barriers between the ova and the testis. The condom (rubber) is used as a sheath over the penis at the time of intercourse. This prevents the spermatozoa from reaching the female reproductive tract. As it can also prevent the trans-mission of sexually transmitted diseases, including AIDS, its use has increased tremendously. The failure rate has been estimated as between 6% to 17%.
In the female, similar barriers like the diaphragm and cervical cap can be used. The diaphragm is in-serted deep in the vagina, covering the superior por-tion of the vagina and the cervix. The cervical cap is smaller and covers only the cervix. Often, these barri-ers are combined with creams that are spermicidal. The failure rate ranges from 5% to 8%. The failure rate is less if the barrier and spermicide are used together.
Another method, although its failure rate is as high as 25%, is the rhythm method. With this method, the person abstains from intercourse during the days ovulation may occur. The various indicators of ovula-tion already described (e.g., changes in basal body temperature, consistency of the cervical mucus, cal-culation of day of ovulation if periods are regular) are used to estimate time and duration of abstinence.