Emergency contraceptive pills (also known as morning-after pills) are high-dose hormonal tablets taken after sexual intercourse to reduce the chance of pregnancy. They are most effective when taken within 2–3 days after unprotected sex, as they work by delaying ovulation or interfering with fertilization. However, if fertilization has already occurred and an embryo has formed, the pills cannot prevent pregnancy.

Emergency contraceptive pills (emergency contraceptive pills, morning-after pills) are high-dose hormonal tablets taken after sexual intercourse to reduce the chance of pregnancy. This method works best within 2–3 days by disrupting ovulation or fertilization of the egg by sperm. However, if fertilization has already occurred and an embryo has formed, it cannot prevent pregnancy.

 

 

Indications for using emergency contraceptive pills

 

1. After having unprotected sexual intercourse
2. In cases of sexual assault
3. Incorrect use of contraception with a chance of failure, such as condom breakage, slippage, or improper use
4. Missed regular oral contraceptive pills
   • Combined pills: missed 3 or more tablets
   • Progestin-only pill: taken more than 3 hours later than the usual time, or more than 27 hours after the previous tablet
   • Desogestrel-containing pill (0.75 mg): taken more than 12 hours later than usual, or more than 36 hours after the previous tablet
5. Late for injectable contraceptives
   • More than 2 weeks late for norethisterone enanthate (NET-EN)
   • More than 4 weeks late for depot-medroxyprogesterone acetate (DMPA)
   • More than 7 days late for combined injectable contraceptive (CIC)
6. Diaphragm or cervical cap slipped, tore, or broke before removal
7. Failure of the withdrawal method, such as ejaculation in the vagina or on the external genitalia
8. Miscalculation of the “safe period” for intercourse
9. Intrauterine device (IUD) or contraceptive implant expelled

 

Important information about emergency contraceptive pills

 

• Emergency contraceptive pills do not prevent sexually transmitted infections (STIs). If STI prevention is needed, a condom should be used.
• Emergency contraceptive pills are not abortion pills. They only help prevent pregnancy and must be taken before the fertilized egg implants in the uterine lining. If implantation has already occurred, the pills will not affect the pregnancy.
• Emergency contraceptive pills have relatively high side effects. Because they act on the endometrial environment, they affect hormones and can cause menstrual irregularities, nausea, and vomiting. Frequent use may increase the risk of ectopic pregnancy.
• There is a misconception that taking emergency pills without knowing you are pregnant can cause birth defects. There are no reports of fetal malformations in mothers who unintentionally took the pills while already pregnant.
• Taking the first tablet within 72 hours after unprotected intercourse followed by the second tablet can prevent about 75% of pregnancies. If the first tablet is taken within 24 hours, effectiveness increases to about 85%. Therefore, it should be taken as soon as possible after intercourse.
• There is a misconception that emergency pills can be used as a long-term contraceptive method. For couples not ready to conceive and needing ongoing contraception, more suitable and effective methods should be used, such as regular daily oral contraceptives. Frequent use of emergency pills can cause more side effects such as headache, nausea, vomiting, spotting, and a higher risk of ectopic pregnancy.
• Emergency pills do not harm future pregnancies and do not delay the ability to conceive later on.
• If vomiting occurs within 2 hours of taking the pill, the dose should be repeated. Progestin-only emergency pills are preferred over combined pills because they cause less nausea and vomiting. Routine antiemetic use with every emergency pill is not yet recommended.

 

 

Methods of emergency contraception

 

1. Ulipristal acetate (UPA), single 30 mg tablet: has higher efficacy than levonorgestrel, even when taken up to 120 hours after intercourse. UPA can also inhibit implantation by disrupting endometrial preparation, whereas levonorgestrel does not have this effect. (Not yet available in Thailand.)
2. Progestogen-only pill (75 mg) 2 tablets taken 12 hours apart: the first tablet should be taken immediately or within 72 hours. Brands available in Thailand include Madonna, Postinor, and Mary Pink. Alternatively, a single 1.5 mg levonorgestrel dose provides comparable efficacy and side effects.
3. Combined oral contraceptives (100 µg ethinyl estradiol + 0.50 mg LNG) 2 tablets 12 hours apart (Yuzpe method), e.g. using a brand like Yasmin that contains 30 µg estrogen per tablet, therefore 4 tablets are taken at once and another 4 tablets 12 hours later.
4. Insertion of a copper IUD within 5 days after intercourse provides up to 99% protection. Studies comparing levonorgestrel 0.75 mg (LNG) taken twice 12 hours apart with the Yuzpe method found that LNG-only emergency pills prevent pregnancy in about 85% (74–93), while combined estrogen–progestin (Yuzpe) prevents about 57% (39–71). Thus LNG is more widely used. However, studies show that weight and body mass index (BMI) affect LNG efficacy: women over 75 kg have about 5 times higher risk of emergency contraception failure, and women with BMI > 25 kg/m² have about 2 times higher risk of pregnancy. Therefore, women who are overweight should take the pill as soon as possible after intercourse.

 

 

Side effects of emergency contraceptive pills

 

• Irregular menstruation
• Nausea, vomiting, or queasiness
• Headache
• Abdominal pain or cramping similar to menstrual pain
• Increased risk of ectopic pregnancy

 

Who should not use hormonal contraceptives

 

• Cancers of female reproductive organs and breast cancer
• Acute or chronic liver disease, or liver cancer
• History of or current heart and vascular disease
• Hypertension
• Thromboembolic disorders
• Epilepsy requiring anticonvulsant medication
• Diabetes with renal impairment or vascular complications
• Women over 35 years who smoke heavily
• Obesity with high blood lipids
• Migraine with aura

 

Although emergency contraceptive pills are effective, especially when the first tablet is taken immediately after intercourse, they are not recommended as a replacement for regular contraception. This is because of the high hormone dosage, possible side effects, menstrual irregularities, lower abdominal cramping, and the fact that they do not protect against sexually transmitted infections. They should be used only when necessary. After using them, if menstruation is delayed, irregular, there is prolonged bleeding, or abdominal pain does not improve, you should see a doctor.

Emergency contraceptive pills are effective in preventing pregnancy, but they should not be used as a routine contraceptive method. They should be reserved for emergency situations only.

Consult an obstetrics and gynecology specialist at Synphaet Hospital near you
(click the link to make an appointment with a specialist)

• Synphaet Ramintra Hospital
• Synphaet Lamlukka Hospital
• Synphaet Theparak Hospital
• Synphaet Srinakarin Hospital
• Synphaet Serirak Hospital
• Synphaet Kanchanaburi Hospital