Birth control pills can work in one of three ways:
- It can prevent ovulation (releasing an egg from the ovary)
- It can cause the mucus in the cervix to change so that if sperm reach the cervix, they are not allowed to enter, and
- It can make the lining of the uterus thinner to prevent fertilized eggs from implanting in the uterus (Birth Control).
Combination pills prevent a woman's ovaries from releasing eggs. Progesterone pills alone may prevent ovulation, this may not occur reliably every month. It also works by thickening the mucous around the cervix. This prevents sperm from joining with an egg. Combination pills also thicken cervical mucus, and both types of pill may also prevent fertilized eggs from implanting in the uterus.
The combination pill comes in either a 21-day pack or a 28-day pack. One hormone pill is taken each day at about the same time for 21 days. Depending on your pack, you will stop taking pills for 7 days or you will take a reminder pill (that contains no hormones) for 7 days. A woman has her when she stops taking the pills with hormones. Some women prefer the 28-day pack because it helps them stay in the habit of taking a pill every day.
The most common choice is the combination pill. It works with the menstrual cycle. On days 1-5, the pill uses the body’s negative feedback system to prevent ovulation and implantation of an embryo, in the same way the hormones provided by the placenta halt the female cycle during pregnancy. Synthetic estrogen and progesterone in the pills travel through the bloodstream to the hypothalamus and the pituitary gland. The estrogen suppresses production of FSH in the pituitary gland so follicle maturation does not happen. During days 6-10, the pituitary gland steps down production of FSH. Without FSH from the pituitary gland, no dominant follicle develops and there is no increase in estrogen. The uterine lining does not thicken. Days 11-13, the constant low levels of progesterone send a signal to the hypothalamus and pituitary gland to prevent the LH surge. From day 14-21, ovulation does not occur and no ovum is released without the LH. The constant level of progesterone makes the lining of the uterus unfriendly to an embryo. The cervical mucus remains thick. The continued delivery of estrogen and progesterone maintains the suppression of FSH and LH. The placebo pills without any hormone allows for the breakdown and release of the thin uterine lining (American Experience: the pill).
The Progesterone pill is taken every day - there are no reminder pills. On this pill there may be no period or may go several months without a period, which means ovulating is not happening. If there are regular periods, there is probably still ovulation and are at greater risk of getting pregnant.
Birth control pills help women in a number of ways besides prevention of unwanted pregnancy. They control menstrual cramps, make cycles regular, preserve fertility (by decreasing the incidence of ectopic pregnancies) and reduce pelvic inflammatory disease. The pill is used to treat conditions such as anemia, endometriosis, fibrocystic breasts, acne, excessive hair growth and uterine fibroids. They also have been shown to prevent uterine and ovarian cancers.
Over the course of one year about five out of 100 typical couples who rely on the Pill to prevent pregnancy will have an accidental pregnancy. Of course, this is an average figure and the chance of getting pregnant depends on whether you take your birth control pills every day. The Pill is an effective form of birth control, but even missing 1 day increases the chance of getting pregnant. In general, each type of birth control method works depends on a lot of things. These include whether a person has any health conditions or is taking any medications that might interfere with its use. It also depends on whether the method chosen is convenient - and whether the person remembers to use it correctly all the time (Birth Control Pill).
The chart below shows how well each type of birth control works. For every hundred couples using each type of birth control, the chart shows how many of these couples will get pregnant within a year (American College of Obstetricians and Gynecologists, 2003).
Some of the advantages of the pill are it
- does not interfere with sex
- usually makes a woman's period shorter, lighter and less painful
- can help with pre-menstrual symptoms
- protects against two types of cancer - cancer of the ovary and cancer of the womb
- protects against some pelvic infections
- reduces the risk of fibroids (tumors in the womb that are not cancer), ovarian cysts and breast disease that is not cancer
As with all drugs, there may be some undesirable side effects for some women taking the pill. Some side effects that usually clear up after two or three months of use include
- bleeding between periods
- weight gain or loss
- breast tenderness
- nausea — rarely, vomiting
- changes in mood
Nausea and vomiting often can be reduced or eliminated by taking the pill with the
evening meal or at bedtime. Irregular spotting and bleeding happen more frequently with
progestin-only pills than with combination pills.
Other possible side effects include:
- headache
- change in sexual desire
- depression
Serious problems do not occur very often. Birth control pill users have a slightly greater chance of certain major disorders than nonusers do. The most serious is the possibility of blood clots in the legs, lungs, heart, or brain. Women on the pill who undergo major surgery seem to have a greater chance of having blood clots. Blood clots in the legs occur with increased frequency for women who have one or both legs immobilized or are confined to their beds (Planned parenthood, 2003).
The birth control pill has got to be the single most important invention of the 20th century. The pill is over 99.7% effective in preventing pregnancy if used correctly. However, the choice of method is up to the couple. The age, health and lifestyle must be considered when making a contraceptive choice.
