What are the best birth control options for a female patient after unprotected sex?

Emergency Contraception After Unprotected Sex

The copper IUD is the single most effective emergency contraceptive option and should be offered first-line when feasible, as it can be inserted within 5 days of unprotected intercourse and provides ongoing contraception. 1, 2

Recommended Options in Order of Effectiveness

First-Line: Copper IUD

• Most effective emergency contraceptive available, preventing >99% of pregnancies 2, 3, 4
• Can be inserted within 5 days (120 hours) of unprotected intercourse 1, 2
• When ovulation timing can be estimated, insertion is acceptable beyond 5 days after intercourse, as long as it occurs ≤5 days after ovulation 1
• Provides immediate ongoing contraception after emergency use 2, 3
• Contraindicated if: puerperal sepsis, septic abortion, or current STI risk is present 2

Second-Line: Ulipristal Acetate (UPA/ella) 30 mg

• More effective than levonorgestrel, especially 72-120 hours after intercourse 1, 2, 5
• Take as soon as possible within 5 days (120 hours) of unprotected intercourse 1, 2, 5
• Reduces pregnancy rate from expected 5.5% to observed 2.2% when taken 48-120 hours after intercourse 5
• Reduces pregnancy rate from expected 5.6% to observed 1.9% when taken 0-72 hours after intercourse 5
• No pregnancies observed when administered >72 hours after intercourse in clinical trials 5
• Requires prescription 3, 6

Third-Line: Levonorgestrel (Plan B) 1.5 mg

• Take as single 1.5 mg dose (or 0.75 mg twice, 12 hours apart) as soon as possible within 72 hours 1, 2
• Effectiveness decreases significantly after 72 hours 1, 2
• Available without prescription or age restrictions 3, 6
• Less effective in obese women (BMI >30 kg/m²) compared to UPA 1, 5

Last Resort: Yuzpe Regimen (Combined Estrogen-Progestin)

• 100 μg ethinyl estradiol plus 0.50 mg levonorgestrel, repeated 12 hours later 1
• Least effective method with more side effects (nausea/vomiting) 1, 2
• Only use if dedicated emergency contraceptive methods are unavailable 1, 2

Critical Timing Considerations

All emergency contraceptives should be taken as soon as possible after unprotected intercourse, as effectiveness decreases with time. 1, 2, 7

• Copper IUD: effective up to 5 days (120 hours) 1, 2
• UPA: effective up to 5 days (120 hours), with superior efficacy 72-120 hours compared to levonorgestrel 1, 2, 5
• Levonorgestrel: most effective within 72 hours, declining efficacy thereafter 1, 2

Important Management After Emergency Contraception

If Levonorgestrel is Used:

• Hormonal contraception can be started or resumed immediately 2
• Use backup contraception (condoms) for 7 consecutive days after starting hormonal method 2

If UPA is Used:

• Do NOT start or resume hormonal contraception for 5 days after taking UPA 5
• Do NOT use additional levonorgestrel emergency contraceptive pills within 5 days of UPA intake 5
• Use reliable barrier contraception (condoms) for all subsequent intercourse until next menstrual period 5
• After 5-day waiting period, use backup contraception for 7 days when initiating hormonal method 5

If Vomiting Occurs Within 3 Hours:

• Contact provider immediately to discuss taking another dose 5

Follow-Up and Ongoing Contraception

• Pregnancy test recommended if menses delayed >1 week beyond expected date 2, 5
• Seek immediate medical attention for severe lower abdominal pain 3-5 weeks after taking emergency contraception to evaluate for ectopic pregnancy 5
• Consider transitioning to long-acting reversible contraceptive (LARC) methods like IUD or implant, especially for women with history of inconsistent contraceptive use 2

Special Considerations

Obesity (BMI >30 kg/m²):

• UPA maintains better efficacy than levonorgestrel in obese women 5
• Levonorgestrel observed pregnancy rate was 7.4% in obese women vs. expected 4.4% 5
• UPA observed pregnancy rate was 3.1% in obese women vs. expected 4.5% 5

Common Pitfall to Avoid:

Do not start hormonal contraception immediately after UPA - this reduces UPA effectiveness. Wait 5 days, then initiate with 7 days of backup contraception. 5

STI Protection:

Emergency contraception does not protect against HIV or other sexually transmitted infections 2, 5