Contraception allows individuals and couples to control the timing and spacing of pregnancies. The US contraceptive prevalence rate is 65% among reproductive-age women. Efficacy is measured by the Pearl Index (pregnancies per 100 woman-years of use) and by typical-use vs perfect-use rates.

Various contraceptive methods — Contraception encompasses methods to prevent pregnancy through hormonal, barrier, intrauterine, or permanent means. Access to contraception is essential for reproductive autonomy. Source: Unsplash.

Methods by Efficacy

Long-Acting Reversible Contraception

LARC methods (IUDs, implants) are the most effective reversible contraceptives, with typical-use failure rates under 1% per year. They are “forgettable” — require no daily action.

Levonorgestrel IUDs (Mirena, Kyleena, Liletta, Skyla) release progestin locally in the uterus, thickening cervical mucus, suppressing endometrial growth, and partially suppressing ovulation. They are effective for 3-8 years depending on the device. Benefits: reduce menstrual bleeding by 80-90% (Mirena and Liletta are FDA-approved for heavy menstrual bleeding), effective for endometrial protection, non-contraceptive benefits (dysmenorrhea, endometriosis). Side effects: irregular bleeding in the first 3-6 months (spotting, light bleeding — expected, does not require device removal), amenorrhea (50% at 1 year with Mirena). Risks: uterine perforation (1-2 per 1,000 insertions — highest risk in breastfeeding women at 6-12 weeks postpartum), pelvic inflammatory disease (rare — risk highest in first 20 days after insertion, screening for STIs before insertion is recommended), and expulsion (2-10%).

Copper IUD (Paragard) releases copper ions that are toxic to sperm, preventing fertilization. No hormones. Effective for 10-12 years. The most effective emergency contraception (can be inserted up to 5 days after unprotected intercourse). Side effects: increased menstrual bleeding (25-50% increase in blood loss) and cramping — may be problematic for women with heavy bleeding or dysmenorrhea. Benefits: non-hormonal, long duration, no systemic effects.

Contraceptive implant (Nexplanon) is a single 4 cm rod placed subdermally in the upper arm that releases etonogestrel (a progestin) for 3-4 years. It suppresses ovulation and thickens cervical mucus. Failure rate: 0.05% — the most effective reversible contraceptive. Side effects: irregular bleeding (60% — unpredictable, can be weeks of spotting or prolonged bleeding; there is no reliable predictor of bleeding pattern — about 20% develop amenorrhea, 20% have frequent bleeding, 20% infrequent, 20% prolonged, and 20% normal; management: NSAIDs, COCP add-back, or early removal if unacceptable), and insertion site reaction.

Hormonal Methods

Combined oral contraceptives contain estrogen (ethinyl estradiol, typically 20-35 mcg) and progestin. They suppress ovulation, thicken cervical mucus, and thin the endometrium. Typical-use failure rate: 7-9% per year (perfect use: 0.3%). Benefits: regulated cycles, reduced dysmenorrhea, reduced PMS, reduced acne, reduced risk of ovarian (50% reduction), endometrial (40%), and colorectal cancers. Risks: venous thromboembolism (3-4 fold increase — absolute risk 2-5 per 10,000 woman-years vs 0.5-1 per 10,000 in non-users). Risk is highest with cyproterone acetate and desogestrel-containing pills. Migraine with aura is an absolute contraindication. Cardiovascular risk increases in smokers over 35, hypertension, and obesity. Serious risks are rare in healthy, non-smoking women. Cancer risk: while COCPs reduce ovarian and endometrial cancer risk, they may slightly increase breast cancer risk (about 1 additional case per 10,000 woman-years), a risk that decreases after discontinuation.

Contraceptive patch (Xulane, Twirla) delivers ethinyl estradiol and norelgestromin transdermally. Changed weekly for 3 weeks, then patch-free week. Failure rate 7-9% typical. Less effective in women over 198 lbs. Vaginal ring (NuvaRing, Annovera) delivers ethinyl estradiol and etonogestrel. Inserted for 3 weeks, removed for 1 week. Failure rate similar to OCPs. Progestin-only pill (norethindrone 0.35 mg — Micronor) — no estrogen, options for women who cannot take estrogen. Must be taken within the same 3-hour window daily (for norethindrone — drospirenone-only pill, Slynd, has a 24-hour window). Depot medroxyprogesterone acetate (Depo-Provera) 150 mg IM every 12-13 weeks. Failure rate 4-6% typical. Side effects: weight gain (5-10 lbs average in first year), menstrual irregularity progressing to amenorrhea, delayed return to fertility (may take 6-12 months after last injection), decreased bone mineral density (reversible after discontinuation, should not be used beyond 2 years as first-line in adolescents — FDA black box warning).

Barrier Methods

Male condoms (latex or polyurethane) are 82-87% effective typical use (98% perfect use). Benefits: protection against STIs (only method proven to reduce HIV, gonorrhea, chlamydia, herpes, HPV). Female condoms are 79% effective typical use. Diaphragm with spermicide requires fitting, 88% effective typical use. Cervical cap less effective. Sponge 76-91% effective. Spermicide alone is 72% effective typical use (high failure rate, not recommended as sole method). Barrier methods are best used in combination with a more effective method or as backup.

Pelvic exam — Barrier methods such as condoms and diaphragms provide protection against STIs and pregnancy. Source: Unsplash.

★ Key Concept

The best contraceptive method is the one a person will use consistently and correctly. Key considerations: efficacy (LARC methods are most effective — forgettable), health conditions (migraine with aura — avoid combined hormonal methods; hypertension, smoking over 35 — avoid estrogen-containing methods), side effect tolerance (bleeding changes are the most common reason for discontinuation), duration of need (LARC for long-term, OCPs/patch/ring for shorter-term), STI protection (condoms only), non-contraceptive benefits (cycle regulation, acne, bleeding reduction, dysmenorrhea), cost and access, and personal preference. The CDC Medical Eligibility Criteria for Contraceptive Use provides evidence-based guidance for which methods are safe in women with specific medical conditions. Most women can safely use most methods.

Emergency Contraception

Emergency contraception prevents pregnancy after unprotected intercourse or contraceptive failure. Copper IUD (Paragard) inserted within 5 days is the most effective (99% reduction in pregnancy risk). Oral EC options: ulipristal acetate (Ella) 30 mg — effective up to 5 days, superior to levonorgestrel, effective throughout the cycle (including near ovulation, when LNG fails). Levonorgestrel (Plan B One-Step) 1.5 mg — effective up to 3 days, efficacy decreases with time and with BMI over 26. Elle does not work in women with BMI over 35. Combined oral contraceptives (Yuzpe regimen) — less effective and more side effects.

Permanent Contraception

Tubal ligation is a 99.5% effective permanent method. Bilateral salpingectomy (removal of fallopian tubes) is increasingly preferred over ligation due to reduced ovarian cancer risk. Vasectomy (male sterilization) is 99.9% effective, less invasive, and safer, but requires 3 months of continued contraception until azoospermia is confirmed.

Summary

Contraceptive efficacy spans from LARC methods (IUDs, implants — failure rate under 1%) to barrier methods (condoms, diaphragm — 10-20% failure). COCPs, patch, and ring are effective (7-9% failure) with non-contraceptive benefits but require daily or weekly action and carry estrogen-related risks. Emergency contraception is available IUD (most effective), ulipristal acetate (up to 5 days), and levonorgestrel (up to 3 days, less effective near ovulation). LARC methods are recommended as first-line by ACOG, CPS, and major guidelines due to their superior effectiveness.