Contraception (Birth Control)

What Are the Main Types of Contraception?

Contraception falls into seven broad categories: long-acting reversible contraceptives (LARCs), short-acting hormonal methods, barrier methods, fertility awareness-based methods, emergency contraception, permanent methods, and behavioral methods such as withdrawal.^[1][2] Within each category, products differ by hormone dose, route of delivery, or duration.^[1]

LARCs and permanent methods are the most effective and require almost no action from the user.^[14] Short-acting hormonal methods are convenient and reversible, but they depend on correct use.^[3] Barrier methods are the only category that also reduces the risk of most sexually transmitted infections (STIs).^[1]

How Do Long-Acting Reversible Contraceptives Work?

LARCs include intrauterine devices (IUDs) and the subdermal implant - devices that are placed once and then work for several years without daily attention, if there are no side effects. They're the most effective reversible methods available, with failure rates under 1% per year.^[14]

The levonorgestrel IUD (Mirena, Kyleena, Liletta, Skyla) releases a small daily dose of the progestin levonorgestrel directly into the uterus. It thickens cervical mucus, thins the uterine lining, and in some users suppresses ovulation. Different doses cover different time spans - the 52 mg Mirena is now licensed for up to 8 years of contraceptive use.^[5] Beyond contraception, the 52 mg Mirena is also FDA-approved to treat heavy menstrual bleeding, and is often chosen for that reason alone. In its pivotal trial, roughly 9 in 10 users had their monthly blood loss cut by more than half within 6 months (the contraceptive license runs to 8 years, but the heavy-bleeding indication is approved for 5).^[23]

The copper IUD (Paragard) contains no hormones. Copper ions released into the uterus impair sperm motility and trigger a local inflammatory response that prevents fertilization. It can stay in place for up to 10–12 years.^[5]

The contraceptive implant (Nexplanon) is a small, flexible rod that sits under the skin of the upper arm. It releases etonogestrel (a progestin) and works mainly by suppressing ovulation. It is now approved for up to 5 years of use.^[18] Like most hormonal methods, the implant carries a small increase in breast cancer risk. In the largest study to date, that signal ran slightly higher than for levonorgestrel-based methods - about 13 extra cases per 100,000 person-years, versus 5 to 8 for levonorgestrel, though the absolute risk stays low.^[20]

Bottom Line:
LARCs are the most effective reversible methods - once placed, they work for years and don't depend on you remembering anything.^[14]

What Are the Side Effects of LARCs?

The levonorgestrel IUD typically causes irregular bleeding and spotting in the first 3–6 months, after which periods usually become lighter, shorter, or stop entirely; about 20% of users have no periods at all by year one.^[5][11] Some users report hormonal symptoms - acne, headache, breast tenderness, or mood changes, though large studies haven't consistently linked the device to depression.^[5][7]

The copper IUD has no hormonal effects, but users often experience heavier, longer, or more painful periods, especially in the first few months. Some adjust over time, others switch methods.^[11]

The implant most commonly causes irregular bleeding - spotting, prolonged bleeding, or amenorrhea (the absence of a menstrual period) which leads about 1 in 10 users to discontinue the method. Less common side effects include headache, weight changes, acne, and breast tenderness. Rare complications include rod migration and difficult removal.^[18]

All IUDs share three rare procedural risks: expulsion (shifting out of its proper position) – 3–10% in the first year, varying by type; uterine perforation at insertion – about 1–2 per 1,000, higher in breastfeeding women; pelvic infection - limited mostly to the first 3 weeks after placement.^[5]

How Do Short-Acting Hormonal Methods Work?

Short-acting hormonal methods deliver either a combination of estrogen and progestin or progestin alone. Combined hormonal contraception (CHC) suppresses ovulation, thickens cervical mucus, and thins the uterine lining.^[3] Progestin-only methods rely mainly on cervical mucus thickening and, depending on the formulation, on ovulation suppression as well.^[4]

The combined oral contraceptive pill is the most widely used form of CHC. Most modern pills contain ethinylestradiol combined with one of several progestins - levonorgestrel, norethisterone, desogestrel, gestodene, drospirenone, dienogest, or norgestimate.^[3] Pills are typically taken for 21 days followed by a 7-day break or placebo week, although continuous and extended-cycle regimens are now common.^[3]

The progestin-only pill (POP, or "mini-pill") contains a single hormone, most often desogestrel, norethisterone, or levonorgestrel. Desogestrel pills suppress ovulation in most cycles, while older POPs work mainly through cervical mucus and need to be taken in a much stricter time window.^[4] A newer option, the drospirenone-only pill (Slynd), was approved in the US in 2019 – it uses a 24/4 dosing schedule and allows a 24-hour missed-pill window, far more forgiving than the roughly 3-hour window of older progestin-only pills. Because drospirenone has anti-mineralocorticoid activity, it can raise blood potassium and is avoided in people with kidney, liver, or adrenal impairment.^[21]

The contraceptive patch is worn on the skin and replaced weekly. The vaginal ring (NuvaRing, Annovera) sits inside the vagina for 3 weeks at a time. Both deliver ethinylestradiol plus a progestin, and effectiveness is similar to the pill.^[3]

The injectable contraceptive is depot medroxyprogesterone acetate (DMPA, Depo-Provera), given as a shot every 3 months. It works mainly by suppressing ovulation.^[1] In 2024, the CDC formally endorsed self-administration of the subcutaneous formulation, removing the need for a clinic visit every quarter.^[2]

→ Learn more: Ovulatory Disorders

What Are the Side Effects of Short-Acting Hormonal Methods?

Combined hormonal methods (pill, patch, ring) share a similar safety profile.^[3] The most discussed serious risk is venous thromboembolism (VTE) - blood clots in deep veins or the lungs. Absolute risk stays low: about 5 to 12 cases per 10,000 woman-years in users compared with 1 to 5 in non-users. Risk peaks in the first months of use and may be higher with certain progestins such as drospirenone.^[6]

CHC is also associated with a small absolute increase in arterial events - heart attack and stroke, particularly in users who smoke, have high blood pressure, or have migraine with aura.^[1][6] The 2024 US MEC (United States Medical Eligibility Criteria) classifies migraine with aura as a Category 4 condition for CHC, meaning the health risk is considered unacceptable.^[1]

Common reversible side effects include nausea, breast tenderness, headache, irregular bleeding, and mood changes - most settle within the first 3 months.^[3] CHC also has well-documented non-contraceptive benefits: lighter, more predictable periods, less menstrual pain, and reduced risk of ovarian, endometrial, and colorectal cancer.^[8][13] A 2024 systematic review found hormonal contraceptive users had a 36% lower risk of ovarian cancer than non-users.^[8]

Current or recent use of hormonal contraception is associated with a small increase in breast cancer risk.^[19] A 2025 Swedish cohort of more than two million women refined the picture by formulation: desogestrel- and etonogestrel-containing products (including the implant) carried higher risk than levonorgestrel products, while the DMPA injection, the vaginal ring, and the combined drospirenone pill showed no significant increase.^[20] In absolute terms, the added risk is small, and it has to be weighed against the protection these methods give against ovarian and endometrial cancer.^[8][13]

Method-specific issues. The patch can cause skin irritation at the application site and may be less effective in users weighing more than 90 kg (depends on the brand). The vaginal ring can cause vaginal discomfort or unwanted discharge, though both are typically mild.^[3]

The progestin-only pill avoids estrogen-related risks like VTE. Its most common side effect is bleeding pattern change - irregular spotting, prolonged bleeding, or no periods at all. Mood changes, breast tenderness, and headache occur in some users but are less common than with combined methods.^[4]

DMPA is associated with bone mineral density loss during use, which largely recovers after discontinuation. The 2024 US MEC concludes this concern shouldn't prevent prescribing or limit duration of use in healthy adults.^[1] DMPA users may also experience weight gain - averaging about 2 kg over 1–2 years - and a delayed return of fertility, with ovulation taking up to 10 months to return after the last dose.^[1][2]

Findings on mood across hormonal methods are mixed. A 2021 network meta-analysis of randomized trials found no statistically significant worsening of depressive symptoms with hormonal contraception compared with placebo in adult women. Cohort studies, however, suggest a small increased risk of depression diagnosis, especially in the first 1–2 years of use and among adolescents.^[7]

How Do Barrier Methods Work?

Barrier methods physically block sperm from reaching the egg. Their effectiveness depends entirely on correct use every time.^[1]

Male condoms are the most common barrier method, made of latex, polyurethane, or polyisoprene. They're the only contraceptive that also reduces the risk of most STIs, including HIV. Typical-use pregnancy rates are around 13% in the first year.^[1]

Internal (female) condoms, diaphragms, cervical caps, and contraceptive sponges all work on the same principle: a physical barrier at or near the cervix, usually paired with spermicide (a hormone-free agent that immobilizes sperm). Typical-use failure rates run higher - about 17–23%, and most require fitting or correct placement before sex.^[1]

The vaginal pH modulator (Phexxi), approved in 2020 and added to the 2024 CDC framework, is a hormone-free gel applied before sex. It works by keeping vaginal pH acidic enough to immobilize sperm. Typical-use pregnancy rate is around 14%.^[2]

What Are the Side Effects of Barrier Methods?

Barrier methods have no systemic effects - nothing enters the bloodstream. Common issues are local: latex allergy or irritation with condoms, reduced sensation, and the chance of breakage or slippage during use.^[1]

Diaphragms, cervical caps, and contraceptive sponges can increase the risk of urinary tract infection because they press on the urethra. Spermicide use is associated with vaginal and vulvar irritation, which can slightly raise the risk of HIV transmission in users with frequent exposure. Toxic shock syndrome is a rare but serious complication if these devices are left in beyond the recommended time.^[1]

The vaginal pH modulator (Phexxi) can cause vaginal burning, itching, or genital discomfort in either partner. Side effects are typically mild and short-lived.^[2]

What Are Fertility Awareness-Based Methods?

Fertility awareness-based methods (FABMs) identify the fertile window in the menstrual cycle so the user can avoid unprotected sex during that time. They include the Standard Days Method, cervical mucus methods (Billings, TwoDay), basal body temperature tracking, and symptothermal methods that combine signals. Typical-use failure rates range from about 2% with the symptothermal method to over 20% with calendar-only methods.^[12]

What Are the Risks of Fertility Awareness-Based Methods?

FABMs have no physical or hormonal side effects. The main risk is method failure - typical-use pregnancy rates are higher than for most other methods because daily tracking has to be accurate and consistent. Stress, illness, travel, sleep changes, and breastfeeding can all disrupt cycle signals and reduce reliability.^[1]

What Is Emergency Contraception?

Emergency contraception (EC) is used after unprotected sex to prevent pregnancy. Three options are widely available: levonorgestrel pills (1.5 mg, sold as Plan B and others), ulipristal acetate (30 mg, sold as ella), and the copper IUD.^[2]

The copper IUD is the most effective option, with a pregnancy rate under 1% when placed within 5 days of unprotected sex. A 2021 trial in the New England Journal of Medicine also found the levonorgestrel 52 mg IUD to be non-inferior to the copper IUD for emergency contraception.^[10]

Ulipristal acetate is more effective than levonorgestrel pills, especially close to ovulation, and works up to 120 hours after intercourse. Levonorgestrel pills are effective for up to 72 hours.^[2] Neither pill is reliable once ovulation is imminent or has occurred - that's why the IUD is more reliable when timing is unclear.^[2][10]

Important:
Ulipristal acetate and progestin-based hormonal contraception can interfere with each other. The 2024 US SPR recommends starting or restarting hormonal contraception only 5 days after taking ulipristal.^[2]

What Are the Side Effects of Emergency Contraception?

Emergency contraceptive pills are generally well tolerated. Common short-term effects include nausea, headache, breast tenderness, fatigue, and abdominal pain. About 1 in 6 users notices a change in the timing of their next period - either earlier or up to a week later than expected.^[2]

The copper IUD used for emergency contraception carries the same insertion risks and ongoing side effects as when used for routine contraception: cramping at placement, heavier periods, and rare expulsion or perforation.^[5][10]

When Should You Consider Permanent Methods?

Permanent contraception is for people who are certain they don't want any future pregnancies.^[2] Tubal ligation (cutting or blocking fallopian tubes) or bilateral salpingectomy (removal of the fallopian tubes) is the surgical option for women, with a typical-use failure rate of about 0.5%. Vasectomy (cutting or sealing the vas deferens) is the male procedure, with a failure rate of about 0.15%.^[12] Reversal success also declines with the interval since the procedure: in the largest series, sperm returned to the ejaculate in 71–97% of men regardless of timing. Pregnancy rates fell from about 76% when reversal occurred within three years to roughly 30% after 15 or more years. Reversal should never be treated as guaranteed restoration of fertility.^[25]

What Are the Risks of Permanent Methods?

All sterilization procedures carry surgical risks - bleeding, infection, and anesthesia complications. Tubal ligation and salpingectomy are usually performed laparoscopically (minimally invasive procedure through tiny cuts), and most patients return to normal activity within a week.^[2] Bilateral salpingectomy may have an added long-term benefit: a documented reduction in ovarian cancer risk later in life.^[8]

Vasectomy is less invasive and usually done under local anesthesia in an outpatient setting. Short-term effects include scrotal swelling, bruising, and discomfort that typically resolve within a week. About 1–2% of men develop chronic post-vasectomy pain. Crucially, vasectomy does not work immediately. Sperm can persist in the system for weeks, so another method is needed until a semen analysis - done about 8 to 16 weeks after the procedure - confirms azoospermia (complete absence of sperm in the ejaculate) or separate non-motile sperm below a threshold. Once that confirmation is in hand, the procedure is among the most reliable methods available, with a long-term failure rate near 1 in 2,000; the slightly higher 0.15% typical-use figure reflects the small number of pregnancies that occur before the clear sample is confirmed.^[22]

How Effective Are Different Methods?

Effectiveness is measured in two ways: perfect use (using the method exactly as prescribed every time) and typical use (how real people use it). The gap between them tells you how forgiving a method is.^[12]

Source: Eligibility and duration details per U.S. Medical Eligibility Criteria for Contraceptive Use, 2024^[1] and U.S. Selected Practice Recommendations, 2024^[2]. Perfect- and typical-use failure rates from Britton et al. (2020)^[12] and FSRH guidance.^[3][5]

Key Insight:
The biggest effectiveness gap is between methods that depend on user action and those that don't. LARCs and sterilization look almost identical in perfect and typical use because there's nothing to forget.^[14]

What About Contraception After Childbirth?

The weeks after delivery change the calculus, mainly because the risk of blood clots is high right after birth. Combined hormonal methods (pill, patch, ring) should be avoided in the first 21 days postpartum, and for women who are breastfeeding or who have other clot risk factors, generally through the first 6 weeks. Progestin-only methods - the mini-pill, the implant, and the hormonal IUD carry no such restriction and can be started immediately, including right after delivery. Both the copper and hormonal IUDs can be placed within the first 10 minutes after the placenta is delivered, or later at the postpartum visit.^[1] Breastfeeding itself offers some protection: a woman who is fully or nearly fully breastfeeding, has not had a return of her period, and is less than 6 months postpartum has a low chance of pregnancy, though it becomes unreliable as soon as any one of those three conditions changes.^[2]

→ Learn more: Conceiving Tips

How Is Contraception Used in IVF?

Combined oral contraceptive pills are sometimes prescribed before an IVF cycle - not to prevent pregnancy, but to schedule and prepare the cycle. The pill is typically taken for 2 to 4 weeks before ovarian stimulation begins.^[15]

Clinicians use it for three main reasons. First, cycle scheduling - taking the pill lets the clinic time the start of stimulation around staffing, lab capacity, and the patient's life. Second, ovarian cyst prevention - pretreatment may lower the chance of functional cysts forming at the start of stimulation, which can otherwise delay the cycle.^[15] Third, in some patients with PMOS (polyendocrine metabolic ovarian syndrome – the 2026 term that replaced polycystic ovary syndrome [PCOS])24 or low ovarian reserve, the pill is used to suppress baseline LH and synchronize the developing follicle cohort.^[16]

The evidence on cycle outcomes is mixed. The 2020 ESHRE guideline on ovarian stimulation notes that combined oral contraceptive pretreatment in GnRH (gonadotropin releasing hormone) antagonist cycles may reduce live birth or ongoing pregnancy rates after fresh embryo transfer compared with no pretreatment.^[15]

Because of this, many clinics now reserve pretreatment for cases where scheduling or cyst suppression clearly justifies it and prefer protocols that avoid hormonal pretreatment when possible.^[15][16]

Important:
If you're starting IVF, don't stop your current contraception until your clinic tells you to. If you use pretreatment, time it to your cycle plan.^[15]

→ Learn more: Infertility

Do Medications Affect Contraceptive Effectiveness?

Some medications speed up the liver’s metabolism of contraceptive hormones and can lower their effectiveness. The main culprits are enzyme-inducing drugs: the anticonvulsants carbamazepine, phenytoin, and topiramate; the antibiotic rifampin (used for tuberculosis); some HIV medicines and the herbal supplement St John’s wort. These can reduce the reliability of the pill, patch, ring, implant, and progestin-only pills. If you take any of these, three methods stay fully effective: the copper IUD (no hormones), the hormonal IUD (works locally rather than through the bloodstream), and the DMPA injection (the progestin dose is high enough that liver enzyme induction doesn’t bring it below the threshold for ovulation suppression).^[1]

Two clarifications worth making. First, everyday antibiotics that are not enzyme inducers - penicillins, cephalosporins, macrolides, doxycycline, metronidazole, and most others do not reduce contraceptive effectiveness, despite the persistent myth. Second, one reverse interaction matters: combined pills lower blood levels of lamotrigine by about half, so anyone taking it for epilepsy or bipolar disorder should coordinate the pill decision with their prescriber.^[1]

Which Method Should You Choose?

There's no single "best" method, only the best method for you. The 2022 ACOG (American College of Obstetricians and Gynecologists) statement on patient-centered contraceptive counseling emphasizes that contraceptive choice should reflect your values, lifestyle, medical history, and reproductive goals, not just effectiveness rankings.^[9]

Use this short list to start narrowing your options.

• Effectiveness: if the failure rate is your top concern, LARCs and permanent methods are the most effective reversible and permanent options.^[14]
• Hormones: if you can't or don't want estrogen, because of migraine with aura, recent VTE, breast cancer history, or personal preference - progestin-only methods, the copper IUD, barrier methods, FABMs, and permanent methods are all options.^[1]
• Maintenance: if remembering daily or weekly doses is hard, LARCs, injections, or permanent methods reduce the day-to-day demand.^[12]
• STI protection: condoms remain the only method that also reduces STI transmission risks.^[1] Many people pair a more effective method with condoms for that reason.
• Reversibility: most reversible methods restore fertility within 1–3 months of stopping. DMPA can take up to 10 months for ovulation to return fully.^[2]

→ Learn more: Female Infertility

So, What Should You Do Now?

If you're starting or switching contraception, work through these five steps.

Step 1: Identify Your Priorities

Decide what matters most to you - effectiveness, low maintenance, no hormones, STI protection, ability to stop quickly, or cost. Most people weigh two or three of these.^[9]

Step 2: Check Your Medical Eligibility

Review your history for conditions that may rule out specific methods - current VTE, migraine with aura, breast cancer, uncontrolled hypertension, or others listed in the 2024 US MEC.^[1]

Step 3: Compare Methods Within Your Eligible Set

Use a side-by-side comparison of effectiveness, side effects, and how the method is used. The CDC summary chart and FSRH guidelines both offer accessible versions.^[1][3]

Step 4: Re-evaluate After 3–6 Months

Most side effects - bleeding pattern changes, mood changes, breast tenderness settle within 3 months.^[3] If they don't, switching methods is straightforward and common.^[9]

Step 5: Talk to a Clinician or Family Planning Clinic

A clinician can confirm eligibility, fit or insert device-based methods, screen for medication interactions, and help you compare your options against your reproductive goals.^[9]

→ Find a women's health or family planning clinic: MedicalNavigator.com/clinics

Too Long, Didn't Read

• Modern contraception falls into 7 categories, from LARCs and pills to barrier methods, FABMs, and permanent surgery.
• Perfect-use failure rates fall under 1% for the most effective methods; with typical use, LARCs and sterilization stay under 1%, while user-dependent methods range up to about 23%.
• LARCs (IUDs and implants) have failure rates under 1% and last 3–12 years with no daily action required.
• Combined hormonal contraception slightly raises blood clot and breast cancer risk, but cuts ovarian cancer risk by around 36%.
• The copper IUD is the most effective emergency contraceptive, with a failure rate under 1% within 5 days.
• The right method should fit your priorities, medical history, and lifestyle - not only effectiveness rankings.

References

1. Nguyen AT, Curtis KM, Tepper NK, et al. U.S. Medical Eligibility Criteria for Contraceptive Use, 2024. MMWR Recomm Rep 2024;73(No. RR-4):1–126. ↩
2. Curtis KM, Nguyen AT, Tepper NK, et al. U.S. Selected Practice Recommendations for Contraceptive Use, 2024. MMWR Recomm Rep 2024;73(No. RR-3):1–77. ↩
3. Faculty of Sexual & Reproductive Healthcare. FSRH Clinical Guideline: Combined Hormonal Contraception (January 2019, amended October 2023). BMJ Sex Reprod Health 2019;45(Suppl 1). ↩
4. Faculty of Sexual & Reproductive Healthcare. FSRH Clinical Guideline: Progestogen-only Pills (August 2022, amended July 2023). FSRH, London; 2023. ↩
5. Faculty of Sexual & Reproductive Healthcare. FSRH Clinical Guideline: Intrauterine Contraception (March 2023). BMJ Sex Reprod Health 2023;49(Suppl 1). ↩
6. Khizroeva J, Bitsadze V, Sukhikh G, et al. Combined Oral Contraceptives and the Risk of Thrombosis. Int J Mol Sci 2025;26(22):11010. ↩
7. de Wit AE, de Vries YA, de Boer MK, et al. Hormonal contraceptive use and depressive symptoms: systematic review and network meta-analysis of randomised trials. BJPsych Open 2021;7(4):e110. ↩
8. Jahanfar S, Mortazavi J, Lapidow A, et al. Assessing the impact of contraceptive use on reproductive cancer risk among women of reproductive age - a systematic review. Front Glob Womens Health 2024;5:1487820. ↩
9. American College of Obstetricians and Gynecologists. Patient-Centered Contraceptive Counseling - Committee Statement No. 1. Obstet Gynecol 2022;139(2):350–353. ↩
10. Turok DK, Gero A, Simmons RG, et al. Levonorgestrel vs. Copper Intrauterine Devices for Emergency Contraception. N Engl J Med 2021;384(4):335–344. ↩
11. Liu P, Meng J, Xiong Y, et al. Contraception with levonorgestrel-releasing intrauterine system versus copper intrauterine device: a meta-analysis of randomized controlled trials. 00505-4/fulltext) eClinicalMedicine 2024;78:102926. ↩
12. Britton LE, Alspaugh A, Greene MZ, McLemore MR. CE: An Evidence-Based Update on Contraception. Am J Nurs 2020;120(2):22–33. ↩
13. Schrager S, Larson M, Carlson J, Ledford K, Ehrenthal DB. Beyond Birth Control: Noncontraceptive Benefits of Hormonal Methods and Their Key Role in the General Medical Care of Women. J Womens Health (Larchmt) 2020;29(7):937–943. ↩
14. Bahamondes L, Fernandes A, Monteiro I, Bahamondes MV. Long-acting reversible contraceptive (LARCs) methods. Best Pract Res Clin Obstet Gynaecol 2020;66:28–40. ↩
15. ESHRE Guideline Group on Ovarian Stimulation; Bosch E, Broer S, Griesinger G, et al. ESHRE guideline: ovarian stimulation for IVF/ICSI. Hum Reprod Open 2020;2020(2):hoaa009. ↩
16. Gao J, Mai Q, Zhong Y, et al. Pretreatment with oral contraceptive pills in women with PCOS scheduled for IVF: a randomized clinical trial. Hum Reprod Open 2024;2024(2):hoae019. ↩
17. Sundaram A, Vaughan B, Kost K, et al. Contraceptive Failure in the United States: Estimates from the 2006–2010 National Survey of Family Growth. Perspect Sex Reprod Health 2017;49(1):7–16. ↩
18. Organon LLC. [NEXPLANON® (etonogestrel implant) 68 mg radiopaque [prescribing information].](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487f8a62-e142-457c-97cc-2e398fde7594) Jersey City, NJ: Organon LLC; January 2026. FDA-approved label extends contraceptive use to 5 years. ↩
19. Fitzpatrick D, Pirie K, Reeves G, Green J, Beral V. Combined and progestagen-only hormonal contraceptives and breast cancer risk: a UK nested case–control study and meta-analysis. PLoS Med 2023;20(3):e1004188. ↩
20. Hadizadeh F, Koteci A, Karlsson T, Ek WE, Johansson Å. Hormonal Contraceptive Formulations and Breast Cancer Risk in Adolescents and Premenopausal Women. JAMA Oncol 2025;11(12):1497–1506. ↩
21. Palacios S, Colli E, Regidor PA. Efficacy and cardiovascular safety of the new estrogen-free contraceptive pill containing 4 mg drospirenone alone in a 24/4 regime. BMC Womens Health 2020;20(1):218. ↩
22. American Urological Association. Vasectomy: AUA Guideline. Linthicum, MD: American Urological Association; 2026. ↩
23. Bayer HealthCare Pharmaceuticals Inc. [Mirena (levonorgestrel-releasing intrauterine system) [prescribing information].](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dcbd6aa2-b3fa-479a-a676-56ea742962fc) Whippany, NJ: Bayer; 2022. FDA-approved for treatment of heavy menstrual bleeding for up to 5 years. ↩
24. Teede HJ, Bahri Khomami M, Morman R, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. 00717-8) Lancet. Published online May 12, 2026. ↩
25. Belker AM, Thomas AJ Jr, Fuchs EF, Konnak JW, Sharlip ID. Results of 1,469 microsurgical vasectomy reversals by the Vasovasostomy Study Group. J Urol 1991;145(3):505–511. ↩