Daniela Carusi

In the year 2001, over 3 million pregnancies in the United States were unintended, and half of these occurred among women using no contraception. Pregnancy prevention must be addressed in women’s health care, as unplanned pregnancy may negatively affect a patient’s psychological wellbeing and her health. Any woman of reproductive age should be considered at-risk for pregnancy, and the subject should be a routine part of her medical care.

Women must consider a number of factors when choosing a contraceptive:

• mechanism of action (barrier, hormonal, behavioral)
  
• over-the-counter availability and cost
  
• reversibility
  
• level of effectiveness
  
• compliance requirements

Each patient’s needs will vary in each of these categories, and medical providers have an important role in helping women to individualize their choices. At times these considerations may come into conflict. For example, a highly effective and reversible intrauterine device may have costs that seem prohibitive. It is important to maximize contraceptive effectiveness for each patient, which may require overcoming obstacles in cost and compliance.

When assessing an individual patient and helping her to find a method, the provider should investigate the following factors.

Compliance

There are many barriers to consistent contraceptive use. These might include financial cost, forgetting to obtain or take the contraceptive, failure to understand its correct use, concern about risks or side effects, or a partner’s unwillingness to comply with a contraceptive plan.

Social Factors

Certain women may feel that family or cultural concerns limit their contraceptive choices. She should be reminded that this is a private, autonomous choice. Adolescents have the right to speak confidentially to health-care providers about contraception and sexuality; providers are not allowed to divulge these interactions to a teenager’s parents or guardians. Similarly, a woman’s partner may not have access to her medical or contraceptive records without her permission, and a partner’s permission is not required for contraceptive or sterilization consent.

Medical Factors

Source: World Health Organization, Medical Eligibility Criteria for Contraceptive Use. 3rd ed Reproductive Health and Research 2004 Geneva: World Health Organization.

As a good starting point, the provider should find out what method(s) the patient has previously used, and how well these worked for her. Staying with a tested method, and avoiding those methods she feels negatively about, can be extremely helpful.

Behavioral Methods

Behavioral contraception includes natural family planning, or the “rhythm method,” withdrawal, and abstinence. All require a high degree of motivation and compliance on the part of the couple, and patients who choose these methods should be carefully educated on their correct use and risk of failure.

Abstinence

Many religions and cultures actively promote sexual abstinence until marriage. The US government has increasingly funded abstinence-only programs, though there is a paucity of evidence that it effectively prevents pregnancy.

While perfect abstinence is obviously very effective, it may be difficult to maintain. Even highly motivated patients should be encouraged to consider what method they will use when it eventually comes time to have intercourse, and may want to prepare in advance by having barrier methods available.

Withdrawal

With this method, the man removes his penis from his partner’s vagina prior to ejaculation. While perfect use of this method may attain more than 80% effectiveness, the typical failure rate is closer to 30%. The man must not have any semen on his penis prior to ejaculation, and must be able to predict his ejaculation and pull out of the vagina prior to its occurrence.

Natural Family Planning

This method, also known as the “rhythm” method, requires that couples abstain from intercourse during fertile days of the cycle. These include the 5 days prior to, and 24 hours after, ovulation. Women with 26–32-day menstrual cycles may safely avoid intercourse on days 8–19 of the cycle. Alternatively, women may avoid intercourse on days in which they identify cervical mucus. The cervix will actively secrete mucus in the late follicular and ovulatory phases, when she is fertile.

Natural family planning may be 85–90% effective for women who have regular menstrual cycles and are highly compliant. It is generally inappropriate for women with very irregular cycles, those who are breast-feeding or perimenopausal, and those just coming of of hormonal birth control methods. For these women ovulation timing will not be predictable.

Barrier Methods

Barrier methods prevent contact between viable sperm and an egg without the use of hormones. All except the diaphragm are available without a prescription.

Chemical Methods: Spermicides

Spermicides act by killing viable sperm before they reach the upper genital tract. They are prepared as gels, foams, and flms, which are inserted in the vagina. They must be applied prior to every act of intercourse, and may cause vaginal or urethral irritation. They have failure rates of 14–29% in clinical trials, with high rates of discontinuation. Furthermore, they do not protect against human immunodeficiency virus (HIV) acquisition when used alone. They are generally not recommended as the sole method of contraception, but rather are used in combination with a diaphragm, sponge, or condom.

The Contraceptive Sponge

The sponge, recently reintroduced to the American market, consists of a soft disk impregnated with a spermicide. It must be placed within the vagina prior to intercourse, and removed within 24 hours afterward. It is 70–85% effective with typical use.

Male Condom

The male condom consists of a fexible sheath, which the man applies to his erect penis prior to penetrating the vagina. It is most often made from natural rubber latex, though it can also be made from lambskin or polyurethane. Condoms are sold over the counter and are readily accessible. Most are lubricated with a spermicide, though unlubricated (spermicide-free) condoms are also available. They may be safely combined with a water-based lubricant for the couple’s comfort. Oil-based products should be avoided as they may break the latex. With typical use the male condom is 85% effective, which may be increased by combining the condom with a spermicide or any other contraceptive method (such as a sponge, behavioral, or hormonal method).

Among contraceptive methods, the male latex condom has the strongest evidence for preventing HIV transmission, and appears to prevent transmission of herpes simplex virus, gonorrhea, and Chlamydia as well.

Female Condom

The female condom consists of a polyurethane sleeve with rigid rings at both ends. The closed end is inserted into the vagina, and placed in front of the cervix. The open end is left outside of the vagina. They are generally more difficult to use then male condoms, though they give women more control over both contraception and sexually transmitted disease (STD) prevention.

Diaphragm

The diaphragm consists of a rigid ring with an intervening, soft piece of impermeable latex rubber. The ring is placed into the vagina, and in proper position will extend from the posterior vagina to just behind the pubic symphysis. Spermicide must be generously placed within the diaphragm, and must be reapplied with each act of intercourse. The device must be left in place for six hours following the final act of intercourse, at which time it may be removed, cleaned and later reused. Unlike other barriers, the diaphragm is available by prescription only. It must be properly fitted to the patient by a health-care professional, and should be re-fitted after major change of body weight, vaginal surgery, or pregnancy. With typical use, the 1-year effectiveness is approximately 85%.

Hormonal Methods

Contraceptive hormones always contain a type of progestin, and often contain an estrogen as well. They come in many different forms, including the hormonal intrauterine device (IUD), which will be discussed separately. This is a very popular method of contraception, given its relatively high effectiveness (90–99%, depending on the method used), as well as a number of secondary, noncontraceptive benefits.

Mechanism of Action

Progestins can prevent pregnancy in three ways. They thicken the cervical mucus, limiting the ascent of sperm into the uterine cavity. Regular use will also cause the endometrial lining to atrophy, preventing successful implantation if an embryo enters the uterine cavity. In higher systemic doses the hormone also suppresses the hypothalamus. This prevents the monthly surge in luteinizing hormone, which ultimately suppresses ovulation.

Combination hormonal contraceptives contain an estrogen as well as a progestin. The estrogen component contributes to hypothalamic and ovulation suppression, and thus may add to the method’s effectiveness. It also helps to prevent breakthrough bleeding and spotting, which can occur when progestins are used alone.

Formulations