What is the safest way to prescribe emergency contraception?

Emergency Contraception: Evidence-Based Prescribing Approach

The safest and most effective approach to prescribing emergency contraception is to offer the copper IUD as first-line when feasible, or ulipristal acetate (30 mg) as the preferred oral option, particularly when presenting 72-120 hours after intercourse or in women who are overweight/obese. 1

Hierarchy of Effectiveness

The CDC and WHO guidelines establish a clear efficacy ranking for emergency contraception methods 1:

• Copper IUD: Most effective option, can be inserted within 5 days of unprotected intercourse (or up to 5 days after ovulation if timing can be estimated) 1
• Ulipristal acetate (UPA): 30 mg single dose, effective up to 120 hours 1, 2
• Levonorgestrel (LNG): 1.5 mg single dose or 0.75 mg twice (12 hours apart), effective up to 120 hours but declining efficacy after 72 hours 1
• Combined estrogen-progestin (Yuzpe): Least effective and most side effects; not recommended 1

Timing-Based Selection Algorithm

Within 0-72 Hours of Intercourse

• UPA and levonorgestrel have similar effectiveness when taken within the first 3 days, though UPA shows superior pregnancy prevention (1.4% vs 2.2%, P=0.046) 1, 3
• UPA is significantly more effective in the first 24 hours (0.9% pregnancy rate vs 2.5% with LNG, P=0.035) 3
• Either option is acceptable, but UPA may be preferred for maximum efficacy 1, 2

Between 72-120 Hours of Intercourse

• UPA is definitively superior to levonorgestrel in this window, with 0 pregnancies versus 3 pregnancies with LNG (P=0.037) 1, 3
• UPA maintains consistent efficacy throughout the 120-hour window without significant decline (P=0.44), with pregnancy rates of 2.3% at 48-72 hours, 2.1% at 72-96 hours, and 1.3% at 96-120 hours 4, 3
• Levonorgestrel efficacy decreases significantly after 72 hours 1

Patient-Specific Considerations

Overweight and Obese Women

Ulipristal acetate is more effective than levonorgestrel in women who are overweight or obese 1, 2. This is a critical consideration given that levonorgestrel may have reduced effectiveness in this population 1.

Breastfeeding Women

• Both UPA and levonorgestrel can be used, though small amounts pass into breast milk 4
• The copper IUD has no hormonal concerns for breastfeeding 1

Administration Instructions

Ulipristal Acetate Protocol

• Single 30 mg dose taken as soon as possible within 120 hours 1, 2, 4
• Can be taken with or without food 4
• If vomiting occurs within 3 hours, contact provider immediately for possible repeat dose 4
• Critical timing restriction: After taking UPA, wait 5 days before starting or resuming hormonal contraception 2, 4
• Use barrier contraception for 14 days or until next menses after UPA use 1, 2
• Do not use additional levonorgestrel emergency contraception within 5 days of UPA 4

Levonorgestrel Protocol

• Single 1.5 mg dose (preferred) or two 0.75 mg doses 12 hours apart 1
• The second dose can be taken 12-24 hours after the first without compromising efficacy 5
• Can start regular contraception immediately after use 1
• Use barrier method for 7 days when resuming hormonal contraception 1

Copper IUD Protocol

• Insert within 5 days of unprotected intercourse 1
• Provides immediate ongoing contraception 1
• Most effective emergency contraception method overall 1

Advance Provision Strategy

The CDC supports providing advance supplies of emergency contraceptive pills so women have immediate access when needed 1. Evidence shows advance provision increases use 2-7 fold without affecting regular contraceptive patterns or STI rates 1.

Critical Safety Monitoring

• Pregnancy test recommended if withdrawal bleeding does not occur within 3 weeks after taking emergency contraception 2
• Seek immediate evaluation for severe lower abdominal pain 3-5 weeks after use to rule out ectopic pregnancy 4
• Menses may occur earlier or later than expected by several days; delay >1 week warrants pregnancy evaluation 4

Common Pitfalls to Avoid

• Do not delay administration: Efficacy decreases with time for all methods 1
• Do not use UPA more than once per menstrual cycle 4
• Do not start hormonal contraception immediately after UPA—this is a unique requirement compared to levonorgestrel and requires a 5-day waiting period 2, 4
• Do not assume levonorgestrel and UPA are interchangeable—they have different mechanisms, timing windows, and post-administration contraceptive protocols 1, 2
• Emergency contraception does not protect against sexually transmitted infections 4