What is the recommended post coital (after sexual intercourse) pregnancy prevention method for a female patient of reproductive age with no known medical contraindications?

Post-Coital Pregnancy Prevention

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

Primary Emergency Contraception Options

First-Line: Copper IUD

• The Cu-IUD is highly effective as emergency contraception with the highest efficacy of all available methods, reducing pregnancy risk by over 99% when inserted within 5 days of unprotected intercourse 1, 2
• The Cu-IUD can be inserted within 5 days of the first act of unprotected sexual intercourse, or when the day of ovulation can be estimated, it can be inserted beyond 5 days after intercourse as long as insertion occurs ≤5 days after ovulation 1
• This method provides the additional benefit of ongoing highly effective contraception after insertion 2

Second-Line: Ulipristal Acetate (UPA)

• Ulipristal acetate (ella) 30 mg as a single oral dose is the most effective oral emergency contraceptive option, particularly when taken 3-5 days after unprotected intercourse 1, 2
• UPA maintains consistent effectiveness throughout the full 120-hour (5-day) window after unprotected intercourse, with observed pregnancy rates as low as 1.9% when taken within 72 hours and no pregnancies observed when taken 72-120 hours after intercourse 3
• UPA is significantly more effective than levonorgestrel for women who are overweight or obese (BMI >30 kg/m²), making it the preferred oral option for this population 1, 2, 4
• Take one 30 mg tablet orally as soon as possible within 120 hours after unprotected intercourse, with or without food, at any time during the menstrual cycle 3

Third-Line: Levonorgestrel

• Levonorgestrel 1.5 mg as a single dose (or 0.75 mg twice, 12 hours apart) reduces pregnancy risk by at least 75% when initiated within 72 hours after unprotected intercourse 1
• Levonorgestrel has significantly reduced effectiveness after 72 hours, with pregnancy rates increasing at 4-5 days, making it a poor choice beyond 3 days 1, 2
• Levonorgestrel may be less effective in obese women (BMI >30 kg/m²), with observed pregnancy rates of 7.4% compared to expected rates of 4.4% 3
• This option is available over-the-counter without age restrictions in the United States 4, 5

Fourth-Line: Combined Estrogen-Progestin Regimen (Yuzpe Method)

• The combined regimen (100 μg ethinyl estradiol plus 0.50 mg levonorgestrel, repeated in 12 hours) is less effective than UPA or levonorgestrel and is associated with more frequent side effects including nausea and vomiting 1
• This method is rarely used given superior alternatives 6

Critical Timing Considerations

Administration Window

• All emergency contraceptive pills should be taken as soon as possible within 5 days of unprotected sexual intercourse 1
• Earlier administration is associated with higher efficacy for all methods 1
• If vomiting occurs within 3 hours of taking emergency contraception, consider repeating the dose 3

Resuming Regular Contraception After Emergency Contraception

After Levonorgestrel:

• Resume or start regular hormonal contraception immediately after levonorgestrel use 2
• Use a reliable barrier method or abstain for 7 consecutive days after restarting hormonal contraception 2

After Ulipristal Acetate:

• Do not initiate or resume hormonal contraception for at least 5 days after UPA intake, as progestin-containing contraceptives may impair UPA's ability to delay ovulation 2, 3
• After the 5-day waiting period, any contraceptive method can be started, but barrier contraception or abstinence is necessary for 14 consecutive days (or until next menses) 2, 3

Important Clinical Considerations

Patient Selection and Counseling

• Emergency contraception has no known medical contraindications and is safe for women of all ages 4, 6
• A negative pregnancy test is not required before administration, though emergency contraception is not indicated for known or suspected existing pregnancy 3
• Emergency contraception does not cause abortion or harm an established pregnancy if inadvertently taken 4, 6
• Emergency contraception does not protect against sexually transmitted infections or HIV, and patients should be counseled accordingly 1

Special Populations

• For women with BMI >30 kg/m², the Cu-IUD or ulipristal acetate should be offered rather than levonorgestrel due to significantly reduced effectiveness of levonorgestrel in this population 2, 4
• All women who are victims of sexual assault should be offered emergency contraception within 120 hours of intercourse 4

Follow-Up and Ongoing Contraception

• Emergency contraception may alter the timing of the next expected menses; if menses is delayed beyond 1 week, rule out pregnancy 3
• Evaluate women who become pregnant or complain of lower abdominal pain after taking emergency contraception for ectopic pregnancy 3
• Rapid return of fertility is likely after emergency contraception use; subsequent acts of intercourse should be protected by a reliable barrier method until the next menstrual period 3
• Women requesting emergency contraception should be offered information and services for ongoing contraception 4, 5

Advance Provision

• An advance supply of emergency contraceptive pills may be provided so that they will be available when needed and can be taken as soon as possible after unprotected intercourse 1
• Women counseled by their clinician about emergency contraception are significantly more likely to use it when needed 5

Common Pitfalls to Avoid

• Do not delay emergency contraception while waiting for a pregnancy test - treatment should be initiated immediately based on history alone 3
• Do not dismiss the Cu-IUD option - while it requires a clinical visit, it is the most effective method and provides ongoing contraception 1, 2
• Do not start hormonal contraception immediately after UPA - wait at least 5 days to avoid reducing UPA effectiveness 2, 3
• Do not recommend levonorgestrel as first-line for obese patients or when >72 hours have elapsed since unprotected intercourse 1, 2, 4