Contraceptives are devices or methods for preventing pregnancy -- either by
preventing the fertilization of the female egg by the male sperm or by
preventing implantation of the fertilized egg. Contraceptive options for
American women include surgical sterilization (tubal ligation), hormonal
contraceptives (oral contraceptives, Norplant implants, Depo-Provera injections)
the intrauterine device (IUD), barrier devices with or without spermicides (the
diaphragm, the cervical cap, the female condom), and natural family planning
methods. Choosing an appropriate contraceptive is a very individual decision. A
1995 survey of several thousand U.S. women found that the most popular
contraceptives (female or male) were female surgical sterilization (28% usage)
and oral contraceptives (27%). None of the other female contraceptives had
secured the allegiance of more than 3% of users.
Hormones Used in Female Contraceptives
Hormonal contraceptives use either a combination of estrogen and progesterone
or progesterone alone.
Estrogen
Estrogen is the major female hormone and is responsible for female
characteristics. It also has widespread effects on other bodily functions,
including altered calcium content in bones, enhanced reactivity of the blood
vessels, improved cholesterol levels, and increased blood clotting. When used
throughout a menstrual cycle with progesterone, it suppresses the actions of
other reproductive hormones (luteinizing hormone, or LH, and follicle
stimulating hormone, or FSH) and prevents ovulation. Estrogen also changes the
cellular structure of the lining of the uterus (the endometrium) and prevents
implantation of a fertilized egg.
Progesterone
Progesterone alone can prevent pregnancy. It maintains a powerful barrier
against the entry of sperm into the uterus by keeping the cervical mucus thick
and sticky. It suppresses ovulation by inhibiting the hormone LH. It also
changes the lining of the uterus and prevents egg implantation. When used in
contraception, progesterone is referred to by one of several names: progesterone
is actually the name for the natural hormone; progestogen is a synthetic form;
and progestin is the term for any agent -- natural or synthetic -- that causes
progesterone effects. Various forms of progestin (desogestrel, gestodene, and
others) alone or with estrogen are used in oral contraceptives. In addition,
certain specific progestins are used in other contraceptives, such as
levonorgestrel in the Norplant system and depo-medroxyprogesterone acetate in
the injected Depo-Provera (see below for details on specific contraceptive
methods).
Determining Effectiveness
Scientific assessments of contraceptive effectiveness distinguish between
"typical use" and "perfect use." Typical use refers to use
under real-life conditions, in which mistakes (such as forgetting to take a
birth control pill at the right time) sometimes happen, whereas perfect use
assumes that a contraceptive will be used correctly each time intercourse
occurs. Research has shown that the four most effective female contraceptives
are surgical sterilization, the IUD, Norplant implants, and Depo-Provera
injections. They all have an estimated failure rate of less than 1% during the
first year of normal (typical) use. Vasectomy (male surgical sterilization) is,
as far as effectiveness is concerned, the only male contraceptive in the same
league. By comparison, the estimated failure rate of the male latex condom used
without spermicide is 14% with typical use and 3% with perfect use. To put these
rates into perspective, it is worth noting that a sexually active woman who does
not use contraception faces an 85% likelihood of becoming pregnant in the course
of a year.
Common Female Contraceptives
|
Contraceptive |
First Year Failure Rate (Typical) |
First Year Failure Rate (Perfect) |
Protection against Sexually Transmitted Diseases |
Approximate Cost |
|
Female Surgical Sterilization |
NA |
NA (failure less than 1%) |
None |
$1,000 to $2,500. May be covered by insurance. |
|
Oral Contraceptives-combined |
5% |
0.1% |
None |
$20 to $35 per month at pharmacy. Less at family planning clinic. Not
usually covered by insurance. |
|
Oral Contraceptives-progestin-only pill |
5% |
0.5% |
None |
|
|
IUD-Copper T |
NA |
NA (failure less than 1%) |
None -- Increases risk. |
$300 to $700 or more for insertion and tests. Lasts 10 years. Covered
by Medicaid. May be less at family planning clinics. |
|
IUD-Progesterone T |
NA |
NA (failure 2%) |
None -- Increases risk. |
$300 to $700 or more for insertion and tests. Needs annual
replacement. Covered by Medicaid. May be less at family planning
clinics. |
|
Levonorgestrel implants (Norplant) |
NA |
NA (failure less than 1%) |
None |
$500 to $600 for implant procedure and tests; $100 to $200 for
removal. May be covered by some insurers. Insertion -- but not removal
-- is covered by Medicaid. |
|
Injected Progestins (Depo-Provera, Noristerat) |
0.3% |
0.3% |
None |
Costs vary. $120 for first injection and $60 for each following
injection at some women's health centers and family planning clinics.
May be partly covered by insurance or Medicaid. |
|
Diaphragm |
20% (with spermicide) |
6% (with spermicide) |
Some protection for certain STDs (gonorrhea and Chlamydia); results
uncertain for HIV or cervical cancer. May increase risk for urinary
tract infections. |
$13 to $25 for the diaphragm; $50 to $120 for fitting. Needs
bi-annual replacement. $8 to $17 for spermicidal kit. |
|
Cervical cap |
20% (with spermicide; no previous births); 40% (with spermicide;
previous births) |
9% (with spermicide; no previous births); 26% (with spermicide;
previous births) |
Some protection |
Similar to costs for diaphragm. |
|
Female Condom |
12.4% to 22% |
5% |
Possibly protective against HIV and STDs. More research is needed. |
$2.50 per use |
|
Cycle-based fertility awareness method (Rhythm method and others) |
25% |
up to 9% |
None |
Virtually no cost, except for basal thermometer and possibly training
(although usually conducted free through a church). |
Well-Connected Board of Editors
Harvey Simon, M.D., Editor-in-Chief
Massachusetts Institute of Technology; Physician, Massachusetts General
Hospital
Masha J. Etkin, M.D., Gynecology
Harvard Medical School; Physician, Massachusetts General Hospital
John E. Godine, M.D., Ph.D., Metabolism
Harvard Medical School; Associate Physician, Massachusetts General
Hospital
Daniel Heller, M.D., Pediatrics
Harvard Medical School; Associate Pediatrician, Massachusetts General
Hospital; Active Staff, Children's Hospital
Irene Kuter, M.D., D. Phil., Oncology
Harvard Medical School; Assistant Physician, Massachusetts General Hospital
Paul C. Shellito, M.D., Surgery
Harvard Medical School; Associate Visiting Surgeon, Massachusetts General
Hospital
Theodore A. Stern, M.D., Psychiatry
Harvard Medical School; Psychiatrist and Chief, Psychiatric Consultation
Service, Massachusetts General Hospital
Carol Peckham, Editorial Director
Cynthia Chevins, Publisher
