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Oral contraceptives (OCs) are more than 99 percent effective in preventing pregnancy
when used consistently and correctly, and they are safe for nearly all women. More than 70
million women use the pill worldwide, but incorrect use is common, thus lowering its
annual typical effectiveness to about 92 percent.1
OCs are among the most widely studied of all drugs. The benefits of using them far
outweigh the potential risks for almost all women. However, oral contraceptives are not
recommended for women at high risk of cardiovascular disease or women over 35 years old
who are heavy smokers. Also, certain health problems may become worse with pill use.
"The pill is a very safe, highly effective product," says Dr. Laneta Dorflinger,
FHI director of clinical trials. "But we need to find ways to make sure it is used
more effectively and continuously. Since failure during typical use is quite high and
discontinuation rates are 50 percent or even higher in the first year of use, we have to
determine how to help women do better."
Side effects or health concerns are frequently mentioned as reasons for discontinuation,
she says. For example, surveys in some countries where discontinuation rates are greater
than 50 percent show about half of the discontinuations are due to side effects or health
concerns: 24 percent of all pill users in the Dominican Republic stopped using them within
the first year for these reasons, and 29 percent in Peru.2
Changes in menstrual patterns are a frequent complaint, as are headaches, nausea and, less
frequently, vomiting associated with pill use.
Allowing women to choose a contraceptive method from among a variety of good options is
one way to encourage women to continue using any method, Dr. Dorflinger says. Counseling
about potential side effects and providing good management of medical concerns can also
improve use. For example, the quality of counseling affects how well-prepared women will
be to take the pill correctly, in addition to preparing them to handle side effects. In
Zimbabwe, a survey among OC users who had missed their daily pill found only one woman in
three had taken the correct action after missing the pill, illustrating one area where
more thorough counseling may be able to improve effectiveness.3
Side effects and health
Because the hormones in the pill mimic pregnancy, the pill has some side effects that
are similar to those associated with pregnancy. Nausea or vomiting may occur in the first
few cycles of pill use, but are less common in subsequent cycles (taking the pill with
food can minimize nausea). Women may also experience headaches, decreased libido, and
depression or mood change. Other possible side effects include breast tenderness, acne,
and dizziness.
The pill regulates a woman's menstrual cycle, decreasing the amount of bleeding on the
average by about 60 percent because of the reduced thickness of the endometrium. This
effect may be beneficial for many women. For example, pill use can eliminate mid-cycle
pain, which some women experience, and decreases menstrual cramps. Because of the decrease
in bleeding, anemia may decrease.
A few women may experience amenorrhea, while others may have breakthrough bleeding between
periods. Breakthrough bleeding, which can range from spotting to bleeding episodes, is
generally not harmful to a woman's health but may have some cultural or religious
significance. Typically, side effects diminish within a few months after a woman begins OC
use.
Since the pill was first introduced more than 30 years ago, there have been hundreds of
major studies on risks and benefits. Long-term medical risks include the relationship of
the pill to cancers and to cardiovascular disease (see related article). Most women can
use the pill without safety concerns, according to medical eligibility criteria
established by the World Health Organization (WHO).4 It is
safe for nonpregnant women past menarche and up to 40 years old (and usually safe after
age 40), with or without children, of any weight including obese women. Postpartum women
who are not breastfeeding may begin using the pill three weeks after giving birth, and
breastfeeding women may do so after six months, although it is better to delay pill use
until breastfeeding ends. Women can use the pill immediately postabortion. Women can use
the pill if they have mild headaches, varicose veins, anemia, a history of diabetes during
pregnancy, painful or irregular menstrual periods, malaria, benign breast disease, or
thyroid disease, or if they carry viral hepatitis.
Some women should not use the pill under any circumstances, according to WHO. These
include women who are pregnant, have a greatly increased risk of cardiovascular disease,
are both over age 35 and smoke heavily (more than 20 cigarettes a day), or have certain
preexisting conditions that could be worsened by OCs. These preexisting conditions include
current breast cancer, benign liver tumors, liver cancer and active viral hepatitis. High
risks for cardiovascular disease include blood pressure greater than 180/110 mm Hg,
diabetes with vascular complications, complicated valvular heart disease, and a history of
any of these conditions -- deep vein thrombosis, blood clotting in the lung, heart attack,
stroke, or severe recurrent headaches with vision problems.
Under some medical conditions, the pill is not the best choice but is still acceptable if
another method is not readily available or acceptable, or if a provider can monitor the
woman. For example, healthy women over age 40 may generally use the pill, as can those
younger than 35 who smoke. Those with sickle cell disease can use the pill but should be
monitored due to an increased risk of thrombosis. Those with unexplained vaginal bleeding
should usually not initiate pill use until the nature of the bleeding can be evaluated. If
taking drugs that induce liver enzymes, women should usually not use the pill because the
drugs are likely to reduce the effectiveness of OCs. These drugs include rifampicin and
griseofulvin, which are antibiotics, and the following anticonvulsants: phenytoin,
carbamazepine, barbiturates and primidone.
Without good counseling, a woman may not be able to distinguish between an expected side
effect and a medical problem. A simple way to remember the danger signs of a medical
problem is the English acronym ACHES: A for "abdominal" pain that is severe; C
for severe "chest" pain, cough, shortness of breath; H for severe
"headache," dizziness, weakness or numbness; E for "eye" problems
(vision loss or blurring) or speech problems; or S for "severe" leg pain (calf
or thigh). The acronym can be modified to fit other languages.5
These signs help identify a possible cardiovascular- related problem that may occur in the
short term. The long-term risk of using the pill is very small for all women in developing
countries compared to the risk of pregnancy.
There are medical benefits from pill use. Because of the pill's excellent effectiveness in
preventing pregnancy, women taking OCs have less chance of an ectopic pregnancy, where the
fertilized egg develops outside the uterus, a life-threatening condition. Pill use also
lowers the overall risk of symptomatic pelvic inflammatory disease (PID) by about 50
percent, because the thickened cervical mucus helps keep bacteria out, possibly the
thinner endometrium provides less fertile ground for bacterial growth, and the decreased
menstrual flow reduces the chance of pathogenic growth or movement of bacteria up the
fallopian tubes.
False rumors about health problems can lead to discontinuation or incorrect use.
"Some women think the pill is unnatural and may cause blocked tubes," says Dr.
Olivia McDonald, medical director of the National Family Planning Board in Jamaica, who is
working with FHI and the Medical Association of Jamaica to provide contraceptive update
seminars for Jamaican physicians, nurses and other health professionals. "So as not
to keep this unnatural thing in their body, they don't use the pill regularly," thus
lowering effectiveness.
OCs dissolve in the stomach and are rapidly absorbed into the bloodstream, just like other
medicines. They do not build up in a woman's body. Nor does a woman need a "rest
period" from taking the pill. Taking a rest will only increase a woman's chance of an
unplanned pregnancy. Also, pills do not cause birth defects when a woman goes off the pill
and gets pregnant.
Mechanism of Action
OCs work primarily by suppressing ovulation, while also affecting the cervical mucus
and endometrium. OCs alter the natural production of estrogen and progestin in the body,
suppressing the follicle stimulating hormone (FSH) and luteinizing hormone (LH). In a
woman taking the pill, the brain does not trigger the normal surge of FSH and LH needed
for the follicle to mature and release an egg. The pill keeps the cervical mucus thick to
prevent sperm penetration. It also causes the endometrium not to thicken as much as
normal, thus making implantation unlikely in the rare event that fertilization takes
place.
The cervical mucus action is particularly important for the progestin-only pill (POP),
which does not cause the extent of ovulation suppression seen with combined pills (those
containing both estrogen and progestin). The mucus thickens two to three hours after a POP
is taken, but remains thick for only about 24 hours unless another pill is taken. That is
why the POP must be taken at about the same time, every 24 hours. If a POP is missed even
by just three hours, a woman should use a back-up method if she has sexual intercourse.
The pill used today has changed substantially from the product that first went on the
market in 1960. The original, "high-dose" pill had up to 150 micrograms (mcg) of
estrogen, compared to today's "low-dose" pill of 35 mcgs or less. The amount of
progestin has also declined substantially. More recently, new progestins have been
developed for low-dose OCs, which some call the "third generation" pills.
The new formulations were designed to reduce safety risks and side effects. The low-dose
pill, with much less estrogen, for example, has less impact on blood pressure, blood
clots, carbohydrate metabolism and other factors for cardiovascular-related diseases.
Lower doses of estrogen have been associated with less nausea, vomiting and headaches.
Some researchers think the third-generation pills with the new progestins also reduce side
effects, for example, reducing rates of amenorrhea. Others feel the literature is not
clear. 6
Studies have not found clear connections between different pill formulations, changes in
side effects and resulting discontinuation rates. A multicenter clinical trial involving
almost 1,700 women assessed the relationship between side effects and discontinuation
rates, comparing women using a 50 mcg and 35 mcg pill. The low-dose users reported
significantly more intermenstrual bleeding, while those taking high doses reported more
breast discomfort. "There were no significant differences between the groups for
gross cumulative life table discontinuation rates," reported Vivian McLaurin and
Randy Dunson of FHI, who coordinated the study.7
The most common pill form is monophasic, where the hormone levels are constant throughout
the 21 days of active pills. Combined OCs also exist in biphasic and triphasic forms,
where the ratio of estrogen and progestin varies among the active pills, twice during the
cycle for the biphasic and three times for the triphasic. This variation allows the pill
to mimic a woman's natural hormonal cycle more closely in the hopes of reducing side
effects, although research has not generally shown this to be true. Most pills used in
developing countries are monophasic.
Who can take the pill?
The pill is ideally suited for women who want to delay pregnancy and space children.
Fertility almost always returns soon after a woman quits taking the pill. The pill is a
good choice for those who want to control their own contraception. A woman can use the
pill without a partner's knowledge, if desired. Women must arrange for resupply on a
regular basis and be conscientious about taking the pill throughout the cycle.
According to WHO, breastfeeding women who want to take the pill should use the
progestin-only pill, beginning no sooner than six weeks after delivery if fully
breastfeeding. In general, combined oral contraceptives are not recommended for
breastfeeding mothers because estrogen diminishes the amount of breastmilk. Although
combined OCs may be used six weeks postpartum if lactation is well- established and other
options are not available or acceptable, ideally breastfeeding women should not use
combined pills until at least six months postpartum.
A U.S. Agency for International Development panel of experts from several collaborating
organizations, including FHI, has identified procedures health providers need to follow in
order to distribute the pill safely.8 The only essential
procedure is good counseling on efficacy, side effects, changes in menstrual patterns,
correct use, problems that require seeing a health-care provider, and STD protection.
Distribution does not need to be confined to clinics. Community-based distribution systems
can follow these procedures, making the pill more easily accessible.
Sometimes unnecessary procedures are required before prescribing the pill. Providers in
many countries require that a woman be having her menstrual period in order to get a
prescription for the pill, to ensure that she is not pregnant. This step is medically
unnecessary since screening at any time can reasonably assure that a woman is not
pregnant. An unplanned pregnancy may result if a woman must wait several weeks before
beginning the pill. Providers can be reasonably sure that a woman is not pregnant if she
has not had pregnancy symptoms, such as absent or altered menses, and she is within the
first seven days of onset of normal menses, or has not had recent sexual activity, or has
been correctly and consistently using a reliable method.
Some procedures, such as breast exams and blood pressure tests, may be indicated for some
women before beginning OCs. However, pelvic exams and screening for cervical cancer and
STDs should not be routinely required for OC use, but may be appropriate for good
preventive healthcare. Routine lab tests for cholesterol and other functions have no
relationship to safe pill use and should not be required before pill use.
In Senegal, the expense of lab tests was compared with possible safety risks. Before 1990,
full laboratory tests were routinely given to women before they could receive the pill. A
prospective study of 410 women found that the cost to the woman of the required laboratory
tests ranged from U.S. $55 to $216, as much as five times the monthly per capita income in
Senegal. Of the 410 women, 20 were found to have possible health problems upon initial
testing. Nine of the 20 returned for retesting. Of those, only one was confirmed as having
a problem that meant she should not take the pill. The study and a subsequent meeting led
to a change in policy in Senegal, with the government no longer requiring laboratory
testing before pills can be prescribed. "However, many doctors and midwives have
resisted the recommendation, and laboratory testing prior to prescriptions of the pill is
still widespread in urban Senegal," reported John Stanback of FHI, the study
coordinator, and his colleagues.9
STD/HIV considerations
Oral contraceptives do not protect against sexually transmitted diseases (STDs),
including HIV. If a woman is at risk of becoming infected with an STD, she should use
condoms consistently regardless of her OC use.
"Pills are designed to prevent pregnancy, and they do it well," says Dr. David
Grimes, chief of obstetrics and gynecology at San Francisco General Hospital, University
of California at San Francisco, who has published reviews on pill safety issues.
"Pills are not designed to protect against STDs. I have a coffee pot that works very
well, but it can't answer the phone. For the phone, I had to buy an answering machine. The
coffee pot was never intended to answer the phone. Nor was the pill designed to protect
against STDs."
Research is not clear on the possible relationship of OC use to the transmission of STDs.
Women using the pill are more likely to have chlamydial cervicitis, an STD. Transmission
of HIV can be more likely if a person has an STD, including chlamydial infection. However,
research has not shown whether there is an association between pill use and risk of HIV
transmission.
A recent animal study has raised concerns about a possible increased risk. In the study,
rhesus monkeys were given doses of the hormone progesterone, the body's natural form of
progestin. The monkeys were found to be more likely to become infected after exposure to
simian immune deficiency virus (SIV), a virus similar to HIV in humans. However, data from
human studies are inconsistent. More research is needed to assess the implications of this
study among humans (see related article).
-- William R. Finger
Footnotes
- Moreno L, Goldman N. Contraceptive failure rates in
developing countries: Evidence from Demographic and Health Surveys. Int Fam Plann
Perspect 1991; 17(2): 44-49.
- Dominican Republic: Demographic and Health Survey 1991.
Peru: Demographic and Health Survey 1991-1992. Calverton, MD: Macro International Inc.,
1992.
- Zimbabwe: Demographic and Health Survey 1994.
Calverton, MD: Macro International Inc., 1995.
- Improving Access to Quality Care in Family Planning:
Medical Eligibility Criteria for Contraceptive Use. Geneva: World Health Organization,
1996.
- Church CA, Rinehart W. Counseling clients about the
pill. Popul Rep 1990; Series A(8): 11.
- Hatcher RA, Trussell J, Stewart F, et al. Contraceptive
Technology Sixteenth Revised Edition. New York: Irvington Publishers, Inc., 1994.
- McLaurin VL, Dunson TR. A comparative study of 35 mcg
and 50 mcg combined oral contraceptives: Results from a multicenter clinical trial. Contraception
1991; 44(5): 489-503.
- Curtis KM, Bright PL, eds. Recommendations for
Updating Selected Practices in Contraceptive Use: Results of a Technical Meeting, Volume
1. Chapel Hill: Technical Guidance Working Group, U.S. Agency for International
Development, 1994.
- Stanback J, Smith JB, Janowitz B, et al. Safe provision
of oral contraceptives: The effectiveness of systematic laboratory testing in Senegal. Int
Fam Plann Perspect 1994; 20(4): 147-49.
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