Birth Control – Options, Efficacy, and Side Effects

What is Birth Control?

Birth control (contraception) is widely used by women who would like to postpone or avoid pregnancy.  There are a wide variety of contraceptive methods available for use.  This may include intrauterine devices, pills, patches, rings, implants, and injections.  Some methods are more effective and longer-lasting than others.  For example, intrauterine devices have very high efficacy and can provide contraception for 3-10 years while oral birth control pills must be taken daily and have slightly lower efficacy.

The most common form of birth control is hormonal birth control. These medications and devices are focused on altering the normal hormone cycles that result in ovulation. There are some non-hormonal options that will also be discussed in this article. 

Hormonal birth control may also be useful in individuals with coexisting conditions such as acne vulgaris or menstrual migraine headache; however, certain conditions also increase the risk of complications from hormone-based contraceptives.

Who Should Use Birth Control?

There are birth control options available for nearly every woman. However, the most common type, hormonal birth control, is not appropriate for some individuals. There are several conditions and characteristics that increase the risk of severe side effects from hormonal birth control. The most common contraindications to hormonal birth control include:

• Smoking combined with an age over 35
• Multiple cardiovascular risk factors or ischemic heart disease
• Hypertension or history of stroke
• Venous thromboembolism or hereditary thrombophilia
• Systemic lupus erythematosus
• Migraine with aura
• Breast cancer
• Cirrhosis or hepatocellular cancer

How Does Birth Control Work?

Contraceptives work through various mechanisms to prevent pregnancy Intrauterine devices sit within the uterus and prevent pregnancy by irritating the lining of the uterus and releasing low levels of hormones or copper ions.  

Oral contraceptives work through several mechanisms to prevent pregnancy.  This includes suppression of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which leads to decreased release of pituitary luteinizing hormone (LH) and follicle stimulating hormone (FSH).  Inhibition of the LH surge during mid-cycle prevents ovulation from occurring and prevents the release of an occyte (egg) from the ovaries. 

Essentially, oral contraceptives trick your body into thinking that pregnancy is already ongoing and there is no need to release another oocyte on a monthly basis.

How Effective is Birth Control?

Various methods of birth control are more effective than others.  The most effective therapies include intrauterine devices, contraceptive implants, and surgical sterilization. These methods result in the lowest pregnancy rates (less than 1 pregnancy per 100 women annually).  Their high rates of success can be explained by their automatic nature. Once implanted or performed these methods do not require the patient to take medication or insert a device on a daily basis. 

The next most effective set of therapies include injectable contraceptives, oral contraceptives, transdermal patches, and vaginal rings. Each of these options  are equally effective as long as they are used appropriately and consistently.  These forms of contraception generally result in 6-12 pregnancies per 100 women annually. The majority of the failures related to these options are based on the requirement that the patient remembers to take the pill, get injections every few months, or insert the vaginal ring. 

Other methods such as diaphragms, cervical caps, male condoms, and withdrawal are the least effective methods for contraception (>18 pregnancies per 100 women annually).  Although they can theoretically result in low pregnancy rates, the actual rates of pregnancy are higher due to the high risk of inconsistent or incorrect use.

What Are My Options for Birth Control?

The various medical options for contraception include intrauterine devices, oral pills, patches, vaginal rings, subcutaneous implants, and surgical procedures.  The following will discuss each of these forms of contraception in more detail.

Paragard (Copper IUD) – This form of contraception must be inserted and removed by a clinician.  It lasts for 10 years.  It does not involve hormone exposure but may cause heavier menses and unscheduled spotting.  It is preferred in women who want long-acting contraception and prefer to avoid hormone therapy.

Mirena (levonorgestrel-releasing IUD) - This IUD lasts 3-5 years and uses progestin.  It may lead to lighter bleeding and must be inserted and removed by a clinician.  It may reduce menorrhagia and dysmenorrhea.  It can be associated with spotting.

Contraceptive pill (Ortho Tri-Cyclen), patch, or ring (NuvaRing) – These use estrogen and progestin and cause lighter, predictable withdrawal bleeding. These methods have the highest level of hormone exposure and as such, they are contraindicated in women over the age of 35 who smoke, those with certain estrogen-responsive cancers, and those with a history of blood clots.  They may reduce dysmenorrhea, menorrhagia, and acne vulgaris.  The pill is taken daily, the patch is placed weekly, and the vaginal ring is inserted monthly.

Nexplanon (etonogestrel implant) - This is a device that is implanted just beneath the skin in the inner arm that lasts 3 years and uses progestin.  It leads to lighter menses and may be associated with spotting.  It requires a small incision for insertion and removal.  It is highly effective for long term contraception in women who want to avoid large amounts of hormone exposure and want to avoid estrogen.

Depo-Provera (depot medroxyprogesterone acetate) – this is an intramuscular injection that lasts 12 weeks and uses progestin.  It leads to lighter periods and is associated with spotting.  It requires injection by a clinician.  It is an effective option for women who desire long term therapy and do not want to use intrauterine or implantable devices.

Surgical Sterilization  - this involves cutting the structures that are responsible for moving eggs to the uterus (the fallopian tubes) or sperm to the urethra (the vas deferens). These methods are near 100% effective but cannot be reversed without another surgical procedure. There is a risk of irreversibility making this method appropriate only for those that will not desire children in the future. The risk of complications with these procedures is very low, making it the preferred option in those with certain pre-existing conditions. 

Side Effects of Birth Control

The side effects of birth control depend on the method of contraception.  Intrauterine devices such as Paragard and Mirena are rarley associated with uterine perforation and an increased risk of pelvic infection in the first 20 days after insertion. These devices can also shift within the uterus leading to discomfort and pain.  The contraceptive pill, patch, or ring is associated with an increased risk of venous thrombosis, blood clots within the legs, which can lead to pulmonary embolism, and hepatic adenoma which can lead to internal bleeding.  The Nexplanon (etonogestrel implant) may rarely result in infection or scarring at the insertion and removal site.  Depo-Provera (depot medroxyprogesterone) can cause weight gain, mood changes, and decreases in bone density with long term use.

References:

1. Miller L, Hughes JP. Continuous combination oral contraceptive pills to eliminate withdrawal bleeding: a randomized trial. Obstet Gynecol 2003; 101:653. - https://www.ncbi.nlm.nih.gov/pubmed/12681866
2. Legro RS, Pauli JG, Kunselman AR, et al. Effects of continuous versus cyclical oral contraception: a randomized controlled trial. J Clin Endocrinol Metab 2008; 93:420. - https://www.ncbi.nlm.nih.gov/pubmed/18056769
3. ACOG Committee on Practice Bulletins-Gynecology. ACOG practice bulletin. No. 73: Use of hormonal contraception in women with coexisting medical conditions. Obstet Gynecol 2006; 107:1453. - https://www.ncbi.nlm.nih.gov/pubmed/16738183