Postcoital contraception, commonly referred to as emergency contraception, encompasses medical interventions used to prevent pregnancy after unprotected intercourse or contraceptive failure. These methods are most effective when administered promptly after sexual activity, ideally within 72 to 120 hours. Emergency contraceptive options include hormonal pills and intrauterine devices (IUDs), each varying in mechanism, efficacy, and indications.
Indications for Emergency Contraception Use
Postcoital contraception should be considered in the following scenarios:
- Unprotected intercourse
- Condom breakage or slippage
- Missed oral contraceptive pills
- Sexual assault without contraception
- Incorrect use of other contraceptive methods (e.g., diaphragm, withdrawal)
Timely administration is critical to maximizing effectiveness and minimizing the risk of unintended pregnancy.
Hormonal Emergency Contraceptive Pills
Levonorgestrel (LNG)
Mechanism of Action:
Levonorgestrel works primarily by inhibiting or delaying ovulation. It is ineffective if ovulation has already occurred and does not terminate an existing pregnancy.
Dosage and Timing:
- Single dose of 1.5 mg or two doses of 0.75 mg taken 12 hours apart
- Most effective within 72 hours but may be used up to 120 hours post-intercourse
- Available over-the-counter in many countries
Efficacy:
Reduces the risk of pregnancy by 52–95% depending on how soon it is taken after intercourse.
Ulipristal Acetate (UPA)
Mechanism of Action:
As a selective progesterone receptor modulator, ulipristal acetate inhibits follicular rupture even when the luteinizing hormone surge has begun.
Dosage and Timing:
- Single dose of 30 mg
- Effective up to 120 hours post-intercourse
- Requires a prescription in many regions
Efficacy:
Superior to levonorgestrel, particularly between 72–120 hours post-intercourse.
Combined Oral Contraceptives (Yuzpe Method)
Mechanism of Action:
High-dose estrogen and progestin inhibit ovulation and fertilization.
Dosage and Timing:
- Two doses of ethinylestradiol (100 µg) + levonorgestrel (0.5 mg) 12 hours apart
- Less effective and associated with more side effects
Efficacy:
Approximately 74% reduction in pregnancy risk
Copper Intrauterine Device (Cu-IUD) as Emergency Contraception
Mechanism of Action:
The copper IUD creates a spermicidal intrauterine environment and prevents implantation.
Timing:
- Can be inserted up to 5 days after unprotected intercourse
- Most effective method of emergency contraception
Efficacy:
99% effective in preventing pregnancy when inserted within the recommended window.
Advantages:
- Long-term contraception for up to 10 years
- Suitable for women seeking ongoing pregnancy prevention
Limitations:
- Requires clinical insertion
- May cause increased menstrual bleeding or cramping
Comparative Effectiveness and Considerations
| Method | Time Frame | Efficacy | Availability | Prescription Needed |
|---|---|---|---|---|
| Levonorgestrel | ≤72 hrs (up to 120) | 52–95% | OTC in many areas | No |
| Ulipristal Acetate | ≤120 hrs | 85–98% | Limited | Yes |
| Copper IUD | ≤120 hrs | >99% | Clinical setting | Yes |
| Yuzpe Method | ≤72 hrs | ~74% | Widely available | Varies |
Factors Affecting Emergency Contraceptive Effectiveness
- Timing: Sooner is always better.
- Body Weight: Efficacy of LNG and UPA may be reduced in women with BMI >25–30.
- Drug Interactions: Liver enzyme-inducing drugs (e.g., rifampin, some anticonvulsants) may reduce hormone levels.
- Multiple Acts of Intercourse: Protection applies only to the incident prompting usage; further intercourse requires additional contraception.
Safety and Side Effects
Common Side Effects:
- Nausea and vomiting
- Headache
- Fatigue
- Breast tenderness
- Menstrual irregularities
Serious Adverse Effects:
Rare, but include ectopic pregnancy if emergency contraception fails. Clinical follow-up is necessary if menstruation is delayed by more than one week.
Counseling and Follow-Up Care
Patients should be counseled on:
- The temporary nature of emergency contraception
- Initiation of regular contraceptive methods after EC use
- Need for STI screening if indicated
- Pregnancy testing if menses are delayed
Ulipristal acetate users should avoid hormonal contraception for five days post-dose to maintain efficacy.
Special Populations and Considerations
Adolescents
Emergency contraception is safe and effective for adolescents. Confidential access is essential.
Breastfeeding Women
Levonorgestrel is safe. For ulipristal, delay breastfeeding for 24 hours post-dose.
Sexual Assault Victims
Should be offered EC alongside STI prophylaxis, psychological support, and medical evaluation.
Public Health Implications
Ensuring access to emergency contraception is a cornerstone of reproductive health. Postcoital contraception serves not only as a critical backup method but also reinforces autonomy, reduces unintended pregnancies, and contributes to lowering abortion rates globally. Widespread education and removal of access barriers remain paramount.
Postcoital contraception is a safe, effective, and essential intervention in modern reproductive healthcare. From levonorgestrel to copper IUDs, multiple options empower individuals to make informed choices based on timing, preference, and health status. Structured counseling and equitable access must be integrated into all levels of care to ensure reproductive autonomy and prevent unintended pregnancies.
