Emergency Contraceptive Pills (Emergency contraceptive pills, Morning-after pills) are high-dose hormone tablets taken after sexual intercourse to reduce the chance of pregnancy. This method is effective within 2–3 days by interfering with ovulation or fertilization. However, it cannot prevent pregnancy if fertilization and implantation have already occurred.
Indications for Emergency Contraceptive Pills
- After unprotected sexual intercourse
- In cases of sexual assault
- When contraceptive failure occurs (e.g., condom breakage, slippage, or incorrect use)
- Missed oral contraceptive doses:
- Combined pills (3 or more tablets missed)
- Progestin-only pills missed by more than 3 hours from the usual time (or over 27 hours since the last pill)
- Desogestrel-containing pill (0.75 mg) missed by more than 12 hours (or over 36 hours since the last pill)
- Overdue contraceptive injection:
- Over 2 weeks late for Norethisterone Enanthate (NET-EN)
- Over 4 weeks late for Depot-medroxyprogesterone acetate (DMPA)
- Over 7 days late for Combined Injectable Contraceptive (CIC)
- Diaphragm or cervical cap dislodged, torn, or broken before removal
- Withdrawal method failure (e.g., ejaculation in the vagina or external genitalia)
- Miscalculation of the rhythm method (safe days)
- IUD or contraceptive implant displacement
Things to Know Before Taking Emergency Contraception
- Emergency pills do not prevent STIs. They are only intended to prevent pregnancy. To prevent sexually transmitted infections, using a condom is the best method.
- Emergency pills are not abortion pills. They work before the egg implants in the uterine lining. If implantation has already occurred, the medication will not be effective.
- Emergency pills have high side effects. They affect the uterine environment and hormonal balance, potentially causing irregular periods, nausea, and vomiting. Frequent use may increase the risk of ectopic pregnancy.
- It is a misconception that they cause birth defects. Reports show no evidence of birth defects in infants born to mothers who unknowingly took the pill while pregnant.
- Taking the first dose within 72 hours followed by a second dose provides approximately 75% effectiveness. If taken within 24 hours, effectiveness increases to 85%. It is recommended to take the first dose as soon as possible.
- Not for long-term contraception. For long-term prevention, regular daily pills are more effective. Frequent use of emergency pills leads to side effects like spotting and increased risk of ectopic pregnancy.
- No harm to future pregnancies. It does not delay or affect the ability to get pregnant in the future.
- Vomiting within 2 hours requires a repeat dose. Progestin-only pills are preferred over combined pills due to lower rates of nausea. Anti-nausea medication is not routinely required.
Emergency Contraception Methods
1. Ulipristal acetate (UPA)
A single 30 mg dose is more effective than Levonorgestrel and can be taken up to 120 hours after intercourse. UPA also interferes with the uterine lining to prevent implantation, whereas Levonorgestrel does not. (Not yet available in Thailand).
2. Progestogen-only pills (0.75 mg)
Two doses taken 12 hours apart, with the first dose taken within 72 hours. Common brands in Thailand include Madonna, Postinor, and Mary Pink. Alternatively, a single 1.5 mg dose of Levonorgestrel offers similar effectiveness and side effects.
3. Combined Oral Contraceptive pills (100 μg of ethinyl estradiol + 0.50 mg of LNG)
Two doses taken 12 hours apart (Yuzpe method). For example, using Yasmin (30 mcg estrogen per pill) requires 4 tablets per dose, repeated after 12 hours.
4. Copper IUD Insertion within 5 days
Provides up to 99% effectiveness. Studies show that single-ingredient LNG pills have an 85% effectiveness rate, while the Yuzpe method (combined estrogen and progestin) provides only 57% effectiveness.
Limitations of Emergency Contraception
While LNG is popular, studies indicate that body mass index (BMI) affects its performance:
- Women weighing over 75 kg: Have a 4.5 times higher risk of failure compared to those weighing less.
- Women with BMI > 25 kg/m²: Have double the risk of pregnancy. It is crucial to take the medication as soon as possible.
Side Effects
- Irregular menstruation
- Nausea and vomiting
- Headache
- Abdominal pain (similar to menstrual cramps)
- Risk of ectopic pregnancy
Contraindications (Who should avoid hormonal contraception)
- Female reproductive organ cancer and breast cancer
- Acute liver disease, cirrhosis, or liver cancer
- History of or current cardiovascular disease
- High blood pressure
- Thromboembolism (Blood clots)
- Epilepsy patients on anti-convulsant medication
- Diabetes with renal or vascular complications
- Smokers over age 35, obesity, or high blood lipids
- Migraine with aura
Summary
While emergency pills are effective, they are not recommended as a replacement for regular contraception due to high hormone levels, potential side effects, and inability to protect against STIs. Use only when necessary.
If you experience abnormal bleeding, missed periods, persistent pain, or severe vomiting after use, please consult a doctor immediately.
Last updated:
29/07/2020
