Oral Contraception

September 20, 2011

Oral contraceptives (birth control pills) are either combined estrogen and progestin or progestin-only formulations that prevent conception. Estrogen is the female hormone secreted by the ovary in the first half of the menstrual cycle. Progesterone is the hormone produced by the ovary in the second half of the cycle. The pill’s estrogens and progestins (substances that behave like progesterone in the body) are synthetic imitators of the body’s natural hormones.

The most commonly used type of birth control pill is the combined oral contraceptive. These are formulations containing combinations of various types and dosages of estrogens and progestins. The combined pills are cycles of 3 weeks of active, hormone-containing pills and 1 week of inactive placebo pills. Combined oral contraceptives may be monophasic (contain the same dose of hormone for 3 weeks of active pills) or multiphasic (containing various doses of hormones in the active pills). Monophasic pills are one color for the three weeks of active pills and a different color on the inactive week. Multiphasic oral contraceptives are multicolored pills during the active pills specifying different dosages throughout the cycle as well as a separate color for the inactive week. There is no real advantage to either type of pill. Pills are taken daily at about the same time. Menses begins during the week of inactive pills. The primary action of combined oral contraceptives is suppression of ovulation, thus preventing conception. In addition, they also thicken the cervical mucus preventing sperm from ascending into the uterus and fallopian tubes and change the lining of the uterus making implantation less likely.

Birth control pills are sometimes prescribed “continuously.” In this case the patient does not take the placebo pills and rather goes directly to the next pack of active pills. This method is used to eliminate some or all menstrual periods.

A second type of oral contraceptive pill is the progestin-only or “minipill.” These formulations contain only a progestin. The pill pack contains 28 active hormonal pills that are the same color throughout. There is no week of inactive/placebo pills. The progestin-only oral contraceptives prevent ovulation in some women; however, the primary method of contraceptive action is to thicken cervical mucus, preventing sperm from ascending into the upper reproductive tract, thus inhibiting conception. The cervical mucus begins to thin within 23 hr so these pills must be taken very consistently every 24 hr. Because the progestin-only pills contain no estrogen, they can be used by women who may have conditions that preclude the use of combined oral contraceptives such as history of blood clotting disorders; smokers who are over 35; women who are lactating; those who experience severe nausea with estrogen intake; those who experience breast tenderness, severe headaches, or hypertension while taking combined pills.


The benefits of both types of pills include:

  1. Excellent contraception. Combined oral contraceptives have a perfect use failure rate of 0.1% (number of pregnancies per 100 couples using it for 1 year of use). Progestin-only pills have a perfect use failure rate of 0.5%. Typical use pregnancy rate for both types of oral contraceptives is 5%. Because of the effectiveness of the pill, it is estimated that for every 100,000 users, 117 ectopic pregnancies, 10,500 spontaneous abortions (miscarriages), and 10,407 term pregnancies requiring cesarean sections are prevented (Dickey, 2000).
  2. Reversibility. Fertility returns rapidly after stopping oral contraceptives. Pills have absolutely no effect on future fertility although it can take somewhat longer to become pregnant after stopping pill use. The median time from discontinuation to conception is 3 months for combined pills and less than 3 months for minipills.
  3. Not coitally related. Pills are taken daily, not just used at the time of intercourse. Therefore, women are protected consistently from unintended pregnancy. It is not necessary to interrupt the spontaneity of sexual activity to use this method.
  4. Safety. Pills are a very safe method of contraception throughout the reproductive years. No studies have demonstrated adverse effects of long-term use. Oral contraceptives are safe for use during the full span of reproductive years in healthy, nonsmoking women. It has been well demonstrated that hospitalizations for adverse health events prevented by oral contraceptives (unintended pregnancy, ovarian cysts, and invasive cancers of the ovary and endometrium) vastly outweigh hospitalizations for conditions related to pill use. There is also no reason to take a rest or holiday from taking the pill. This increases the risk of pregnancy and has no benefit whatsoever.
  5. May be used for emergency contraception. Within 72 hr of unprotected intercourse, larger doses of certain birth control pills may be used to prevent an unintended pregnancy. The failure rate with this method is between 1 and 3% depending on what method is used. Telephone hotline: 1-888-NOT-2-LATE (1-888-668-2528).
  6. Noncontraceptive benefits. Combined pills provide protection against osteoporosis, functional ovarian cysts, and benign breast disease. They also decrease the risk for ovarian cancer and endometrial cancer (cancer of the lining of the uterus) significantly. Longer use conveys greater protection. The pills improve acne and decrease hirsutism (unwanted facial and body hair resulting from excessive male hormones). Both combined and progestin-only pills decrease menstrual cramps and menstrual flow, reduce symptoms of endometriosis, decrease premenstrual syndrome, diminish anemia related to heavy periods, decrease the midcycle pain of ovulation, and lower the risk for pelvic inflammatory disease (infection of the uterus, tubes, and pelvic cavity that can be life threatening).


Disadvantages of oral contraceptives include:

  1. Risk of cardiovascular diseases. Although the risk is very small, use of the pill can predispose women to the most serious risk attributable to combined oral contraceptives, diseases of the heart and circulatory system. Cardiovascular problems such as heart attack, stroke, and blood clots are due to: (1) an increase in coagulability (blood clotting) due to estrogen; (2) an unfavorable change in cholesterol and other fats in the blood due to male hormone activity of progestins; and/or (3) increased blood pressure in susceptible patients due to the estrogen and/or progestin components of the pill. The risk increases with age. Concomitant smoking is a major cause of these complications.
  2. Cost of method. Oral contraceptives can be expensive if they are not covered by insurance. Unfortunately, many insurance companies do not cover oral contraceptives for birth control purposes only. If they are used to treat a medical condition such as severe cramps or irregular periods, the cost may be covered. The cost of pills depends on the type and pharmacy, but they average between $30 and $35 a cycle. They can be obtained at health departments, birth control clinics, or, in some instances, pharmaceutical company programs at reduced cost.
  3. No protection against sexually transmitted diseases. While birth control pills thicken cervical mucus and may decrease the likelihood of pelvic inflammatory disease, they do not prevent gonorrhea, chlamydia, trichomoniasis, HIV, or genital warts and human papillomavirus (HPV) that can cause cervical dysplasia and cancer. Because of changes in the cervix called ectopy, a condition that causes vulnerable cells to be more exposed in the cervical opening, chlamydial infections may be acquired more easily on oral contraceptives. For this reason, it is recommended that latex condoms be used in addition to oral contraceptives for those who are at risk for sexually transmitted infections.
  4. The need to remember to take a pill each day is difficult for many patients. The vaginal ring method of hormonal contraception and the birth control patch may be excellent options for these patients.
  5. Adverse effects directly related to pill use. These include nausea and vomiting, menstrual changes including spotting, headaches (may increase or decrease on the pill), depression (may increase or decrease), decreased libido due to decreased levels of circulating free male hormone, and increased risk of gallstones. These effects can generally be ameliorated by adjustment of dosage or formulation of pills.
  6. Adverse effects that may be related to pill use. Certain types of benign liver tumors have also been associated. Since cervical cancer is related to HPV, pill users may be more susceptible, because they have more sexual partners. Studies that have attempted to control for confounding risk factors have found that the risk of cervical cancer still seems to be slightly higher in patients using the pill.

Birth control pills are safe, effective, and generally very well tolerated. The decision to use an oral contraceptive should be based on personal preference, medical history including conditions that may be exacerbated or improved by pills, the ability to take a pill each day, and economics. They require a prescription by a medical provider who should monitor the patient’s response to the pills and provide preventive screening for breast and cervical cancer as well as sexually transmitted diseases where the risk is great.

SEE ALSO: Acquired immunodeficiency syndrome, Birth control, Chlamydia, Condoms, Ovarian cancer, Ovarian cyst, Pelvic pain, Sexual organs, Uterine cancer

Suggested Reading

  • Dickey, R. (2000). Managing contraceptive pill patients (pp. 10—11). Dallas, TX: EMIS.
  • Hatcher, R., Trussel, J., Stewart, F., Cates, W., Stewart, G., Guest, F., et al. (1999). Contraceptive technology (pp. 405—509). New York: Ardent Media.


  • list of oral contraceptives


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